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Background The syndrome of thyrotoxicosis typically relies on radioactive iodine scans for establishing its etiology. Alternatively, the determination of TSH receptor antibodies (TRAb) helps to distinguish Graves' disease (GD) from thyrotoxic thyroiditis. Current assays are impacted by limitations in sensitivity and/or turnaround time. Therefore, we decided to test a new assay for the detection of TSH receptor stimulating antibodies (TSAb) and compare it with the clinically available assays. Methods We enrolled 110 individuals in 5 cohorts: patients with incident or recurrent Graves' disease (cohort 1); patients with thyroiditis, painless or subacute (cohort 2); patients with Graves' Orbitopathy/Thyroid Eye Disease (TED) in cohort 3; patients with Hashimoto's thyroiditis (cohort 4) and a control group of normal volunteers (cohort 5). The patients were tested with the two clinically available assays: Roche Elecsys anti-TSHR assay (ROC-TBII) from Roche Diagnostics and Thyretain™ TSI Reporter BioAssay Kit (QUI-TSI) from Quidel. In addition, the samples were tested with the aequorin TSAb assay (OTS-TSI) provided by Otsuka Pharmaceutical Co., Ltd. (Tokyo, Japan). The data was collected in a cross-sectional fashion before initiation of therapy. Results We had 36 cases of GD, 17 cases of thyroiditis, 27 cases of TED, 10 cases of Hashimoto's thyroiditis and 20 normal volunteers. OTS-TSI had 100% sensitivity and specificity in distinguishing GD from thyroiditis, identical with QUI-TSI but superior to ROC-TBII (sensitivity 86% and specificity 94.1%). OTS-TSI had 93% sensitivity and 100% specificity for the diagnosis of TED, compared with normal controls. QUI-TSI and ROC-TBII performed similarly in this analysis, demonstrating 82% sensitivity and 100% specificity. The range of detectable values for OTS-TSI was 20 - 29,000 mIU/L and the turnaround time was ≤ 6 hours, without the need for cell culture equipment. Conclusions. OTS-TSI performed excellently, though similarly to QUI-TSI, for the differential diagnosis of GD versus thyroiditis, while being superior in that respect to ROC-TBII. Furthermore, OTS-TSI has superior sensitivity to QUI-TSI and ROC-TBII for TED diagnosis, while retaining high specificity. It has a short turnaround time and avoids the need for cell culture and sterility. Larger studies in US populations are needed for its validation.

Introduction The prognostic utility of cerebrospinal fluid (CSF) phosphorylated tau 217 (p-tau217) and p-tau181 is not understood. Methods Analyses included 753 Mayo Clinic Study on Aging participants (median age = 71.6; 57% male). CSF amyloid beta (Aβ)42 and p-tau181 were measured with Elecsys immunoassays. CSF p-tau181 and p-tau217 were also measured with Meso Scale Discovery (MSD). We used Cox proportional hazards models for risk of mild cognitive impairment (MCI) and linear mixed models for risk of global and domain-specific cognitive decline and cortical thickness. Analyses were stratified by elevated brain amyloid based on CSF Aβ42 or amyloid positron emission tomography for those with imaging. Results CSF p-tau217 was superior to p-tau181 for the diagnosis of Alzheimer's disease (AD) pathology. CSF MSD p-tau181 and p-tau217 were associated with risk of MCI among amyloid-positive individuals. Differences between CSF p-tau measures predicting cortical thickness were subtle. Discussion There are subtle differences for CSF p-tau217 and p-tau181 as prognostic AD markers.

Introduction Blood-based biomarkers of amyloid pathology and neurodegeneration are entering clinical use. It is critical to understand what factors affect the levels of these markers. Methods Plasma markers (Aβ42, Aβ40, NfL, T-tau, Aβ42/40 ratio) were measured on the Quanterix Simoa HD-1 analyzer for 996 Mayo Clinic Study of Aging (MCSA) participants, aged 51 to 95 years. All other data were collected during in-person MCSA visits or abstracted from the medical record. Results Among cognitively unimpaired (CU) participants, all plasma markers correlated with age. Linear regression models revealed multiple relationships. For example, higher Charlson Comorbidity Index and chronic kidney disease were associated with higher levels of all biomarkers. Some relationships differed between mild cognitive impairment and dementia participants. Discussion Multiple variables affect plasma biomarkers of amyloid pathology and neurodegeneration among CU in the general population. Incorporating this information is critical for accurate interpretation of the biomarker levels and for the development of reference ranges.

Background: The GALAD score is a serum biomarker–based model that predicts the probability of having hepatocellular carcinoma (HCC) in patients with chronic liver disease. We aimed to assess the performance of the GALAD score in comparison with liver ultrasound for detection of HCC. Methods: A single-center cohort of 111 HCC patients and 180 controls with cirrhosis or chronic hepatitis B and a multicenter cohort of 233 early HCC and 412 cirrhosis patients from the Early Detection Research Network (EDRN) phase II HCC Study were analyzed. Results: The area under the ROC curve (AUC) of the GALAD score for HCC detection was 0.95 [95% confidence interval (CI), 0.93–97], which was higher than the AUC of ultrasound (0.82, P Conclusions: The performance of the GALAD score was superior to ultrasound for HCC detection. The GALADUS score further enhanced the performance of the GALAD score. Impact: The GALAD score was validated in the United States.

Introduction We aimed to provide cut points for the automated Elecsys Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarkers. Methods Cut points for Elecsys amyloid beta 42 (Aβ42), total tau (t-tau), hyperphosphorylated tau (p-tau), and t-tau/Aβ42 and p-tau/Aβ42 ratios were evaluated in Mayo Clinic Study of Aging (n = 804) and Mayo Clinic Alzheimer's Disease Research Center (n = 70) participants. Results The t-tau/Aβ42 and p-tau/Aβ42 ratios had a higher percent agreement with normal/abnormal amyloid positron emission tomography (PET) than the individual CSF markers. Reciever Operating Characteristic (ROC)-based cut points were 0.26 (0.24-0.27) for t-tau/Aβ42 and 0.023 (0.020-0.025) for p-tau/Aβ42. Ratio cut points derived from other cohorts performed as well in our cohort as our own did. Individual biomarkers had worse diagnostic properties and more variable results in terms of positive and negative percent agreement (PPA and NPA). Conclusion CSF t-tau/Aβ42 and p-tau/Aβ42 ratios are very robust indicators of AD. For individual biomarkers, the intended use should determine which cut point is chosen.

Background Hyperphosphatemia confers adverse cardiovascular outcomes, and commonly occurs in late-stage CKD. Fibroblast growth factor 7 (FGF7) is a phosphaturic peptide which decreases renal phosphate transport in vitro and in vivo. Serum FGF7 concentrations are reduced in hyperphosphatemic patients with hypophosphatasia and are elevated in some hypophosphatemic patients with tumor-induced osteomalacia. No data, however, are available on whether circulating FGF7 concentrations increase to compensate for phosphate retention in CKD patients. Methods This was a cross-sectional study performed among 85 adult patients with varying estimated glomerular filtration rates (eGFR). We measured serum intact FGF7 (iFGF7) concentration using an iFGF7 immunoassay and determined its associated factors. Relationships between eGFR and mineral metabolism biomarkers [phosphate, iFGF7, iFGF23, parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D (1,25(OH)2D)] were explored. Results For eGFRs of ≥ 60 (n = 31), 45–59 (n = 16), 30–44 (n = 11), 15–29 (n = 15), and 2 (n = 12), median (IQ25-75) iFGF7 concentrations were 46.1 (39.2–56.9), 43.1 (39.0-51.5), 47.3 (38.3–66.5), 47.7 (37.7–55.8), and 49.6 (42.5–65.6) pg/mL, respectively (P = 0.62). Significant increases in serum iFGF23, PTH, and phosphate were observed at eGFRs of 2 (95 % CI, 19.25–25.51), respectively, while significant decreases in serum 1,25(OH)2D were observed at an eGFR of 2 (95 % CI, 42.57–61.43). No significant correlation was found between serum iFGF7 and phosphate, iFGF23, PTH or 1,25(OH)2D. In multivariable analyses, body mass index (per 5 kg/m2 increase) was independently associated with the highest quartile of serum iFGF7 concentration (OR, 1.20; 95 % CI, 1.12–1.55). Conclusions Compensatory decreases in circulating 1,25(OH)2D and increases in circulating iFGF23 and PTH, but not iFGF7, facilitate normalization of serum phosphate concentration in early stages of CKD. Whether other circulating phosphaturic peptides change in response to phosphate retention in CKD patients deserves further study.

Context The normal cortisol response 30 or 60 minutes after cosyntropin (ACTH[1–24]) is considered to be ≥18 μg/dL (500 nmol/L). This threshold is based on older serum cortisol assays. Specific monoclonal antibody immunoassays or LC-MS/MS may have lower thresholds for a normal response. Objective To calculate serum cortisol cutoff values for adrenocorticotropic hormone (ACTH) stimulation testing with newer specific cortisol assays. Methods Retrospective analysis of ACTH stimulation tests performed in ambulatory and hospitalized patients suspected of adrenal insufficiency (AI). Serum samples were assayed for cortisol in parallel using Elecsys I and Elecsys II immunoassays, and when volume was available, by Access immunoassay and LC-MS/MS. Results A total of 110 patients were evaluated. Using 18 μg/dL as the cortisol cutoff after ACTH stimulation, 14.5%, 29%, 22.4%, and 32% of patients had a biochemical diagnosis of AI using the Elecsys I, Elecsys II, Access, and LC-MS/MS assays, respectively. Deming regressions of serum cortisol were used to calculate new cortisol cutoffs based on the Elecsys I cutoff of 18 μg/dL. For 30-minute values, new cutoffs were 14.6 μg/dL for Elecsys II, 14.8 μg/dL for Access, and 14.5 μg/dL for LC-MS/MS. Baseline cortisol Conclusion To reduce false positive ACTH stimulation testing, we recommend a new serum cortisol cutoff of 14 to 15 μg/dL depending on the assay used (instead of the historical value of 18 μg/dL with older polyclonal antibody assays). Clinicians should be aware of the new cutoffs for the assays available to them when evaluating patients for AI.

Introduction Measurement of amyloid beta (Aβ40 and Aβ42) and tau (phosphorylated tau [p‐tau] and total tau [t‐tau]) in cerebrospinal fluid (CSF) can be utilized to differentiate clinical and preclinical Alzheimer's disease dementia (AD) from other neurodegenerative processes. Methods CSF biomarkers were measured in 150 participants from the Mayo Clinic Study of Aging and the Alzheimer's Disease Research Center. P‐tau/Aβ42 (Roche Elecsys, Fujirebio LUMIPULSE) and Aβ42/40 (Fujirebio LUMIPULSE) ratios were compared to one another and to amyloid positron emission tomography (PET) classification. Results Strong correlation was observed between LUMIPULSE p‐tau/Aβ42 and Aβ42/40, as well as Elecsys and LUMIPULSE p‐tau/Aβ42 and Aβ42/40 (Spearman's ρ = –0.827, –0.858, and 0.960, respectively). Concordance between LUMIPULSE p‐tau/Aβ42 and Aβ42/40 was 96% and between Elecsys p‐tau/Aβ42 and both LUMIPULSE ratios was 97%. All ratios had > 94% overall, positive, and negative percent agreement with amyloid PET classification. Discussion These data suggest that p‐tau/Aβ42 and Aβ42/40 ratios provide similar clinical information in the assessment of amyloid pathology.

ObjectiveWe studied interrelationships between CSF biomarkers and associations with APOE ε4 genotype, demographic variables, vascular variables, and clinical diagnosis in Olmsted County, Minnesota.MethodsWe included 774 Mayo Clinic Study of Aging participants (693 cognitively unimpaired [CU]; 71 with mild cognitive impairment [MCI]). CSF β-amyloid 42 (Aβ42), total tau (t-tau), and hyperphosphorylated tau (p-tau) were analyzed using Aβ42 CSF, t-tau CSF, and p-tau (181P) CSF electrochemiluminescence immunoassays. Bivariate mixture models were used to evaluate latent classes. We used linear regression models to evaluate independent associations of APOE ε4, demographic factors, cardiovascular risk, and diagnosis with CSF biomarker levels. Results were weighted back to the Olmsted County population.ResultsInterrelationships between CSF Aβ42 and p-tau/t-tau were consistent with 2 latent classes in the general population. In subgroup 1 (n = 547 [71%]), we found a strong positive correlation between Aβ42 and p-tau (ρ = 0.81), while the correlation was much smaller in group 2 (ρ = 0.26, n = 227 [29%]). Group 2 was associated with older age, APOE ε4 genotype, a diagnosis of MCI, and elevated amyloid PET. Overall, APOE ε4 genotype and MCI were associated with Aβ42, while age was associated with p-tau/t-tau. There were no associations with sex, education, or vascular risk.ConclusionWe hypothesize the population without dementia can be subdivided into participants with and without biological Alzheimer disease (AD) based on the combination of CSF Aβ42 and p-tau/t-tau (represented also by the p-tau/t-tau/Aβ42 ratio). In those without biological AD, common factors such as CSF dynamics may cause a positive correlation between CSF Aβ42 and p-tau/t-tau, while AD leads to dissociation of these proteins.

The post-operative management of patients with differentiated thyroid carcinoma (DTC) relies on serial measurements of serum thyroglobulin. Current methodologies for thyroglobulin quantitation vary in their analytical and clinical performance. For years, thyroglobulin radioimmunoassays (RIA) and immunometric assays (IMA) have been used despite analytical interferences from anti-thyroglobulin autoantibodies (TgAb) as well as heterophile antibodies (HAb). TgAb interference limits Tg utility as a tumor marker in ∼30% of TgAb-positive patients. Consequently, additional studies are necessary to rule out persistent or recurrent disease in these patients. Recently, thyroglobulin mass spectrometry assays have been introduced as a solution to the interference problems observed in immunoassays. However, their analytical sensitivity is inferior to the high sensitivity immunoassays. The aims of this review are to: (i) review current thyroglobulin assays; (ii) discuss technical limitations of each assay; and (iii) discuss the clinical uses of thyroglobulin in serum and fine-needle aspirate biopsy washouts for the management of DTC patients. An understanding of the technical advantages and disadvantages of Tg assays is critical for clinicians and laboratorians to effectively use and interpret this test in the management of DTC patients.

AIM To assess the performance of BALAD, BALAD-2 and their component biomarkers in predicting outcome of hepatocellular carcinoma (HCC) patients after liver transplant. METHODS BALAD score and BALAD-2 class are derived from bilirubin, albumin, alpha-fetoprotein (AFP), Lens culinaris agglutinin-reactive AFP (AFP-L3), and des-gamma-carboxyprothrombin (DCP). Pre-transplant AFP, AFP-L3 and DCP were measured in 113 patients transplanted for HCC from 2000 to 2008. Hazard ratios (HR) for recurrence and death were calculated. Univariate and multivariate regression analyses were conducted. C-statistics were used to compare biomarker-based to predictive models. RESULTS During a median follow-up of 12.2 years, 38 patients recurred and 87 died. The HRs for recurrence in patients with elevated AFP, AFP-L3, and DCP defined by BALAD cut-off values were 2.42 (1.18-5.00), 1.86 (0.98-3.52), and 2.83 (1.42-5.61), respectively. For BALAD, the HRs for recurrence and death per unit increased score were 1.48 (1.15-1.91) and 1.59 (1.28-1.97). For BALAD-2, the HRs for recurrence and death per unit increased class were 1.45 (1.06-1.98) and 1.38 (1.09-1.76). For recurrence prediction, the combination of three biomarkers had the highest c-statistic of 0.66 vs. 0.64, 0.61, 0.53, and 0.53 for BALAD, BALAD-2, Milan, and UCSF, respectively. Similarly, for death prediction, the combination of three biomarkers had the highest c-statistic of 0.66 vs 0.65, 0.61, 0.52, and 0.50 for BALAD, BALAD-2, Milan, and UCSF. A new model combining biomarkers with tumor size at the time of transplant (S-LAD) demonstrated the highest predictive capability with c-statistics of 0.71 and 0.69 for recurrence and death. CONCLUSION BALAD and BALAD-2 are valid in transplant HCC patients, but less predictive than the three biomarkers in combination or the three biomarkers in combination with maximal tumor diameter (S-LAD).

Parathyroid hormone (PTH) measurement in serum or plasma is a necessary tool for the exploration of calcium/phosphate disorders, and is widely used as a surrogate marker to assess skeletal and mineral disorders associated with chronic kidney disease (CKD), referred to as CKD-bone mineral disorders (CKD-MBD). CKD currently affects >10% of the adult population in the United States and represents a major health issue worldwide. Disturbances in mineral metabolism and fractures in CKD patients are associated with increased morbidity and mortality. Appropriate identification and management of CKD-MBD is therefore critical to improving clinical outcome. Recent increases in understanding of the complex pathophysiology of CKD, which involves calcium, phosphate and magnesium balance, and is also influenced by vitamin D status and fibroblast growth factor (FGF)-23 production, should facilitate such improvement. Development of evidence-based recommendations about how best to use PTH is limited by considerable method-related variation in results, of up to 5-fold, as well as by lack of clarity about which PTH metabolites these methods recognise. This makes it difficult to compare PTH results from different studies and to develop common reference intervals and/or decision levels for treatment. The implications of these method-related differences for current clinical practice are reviewed here. Work being undertaken by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) to improve the comparability of PTH measurements worldwide is also described.

Background and objective Leptomeningeal metastasis (LM) can occur as a late manifestation of breast cancer and has traditionally been diagnosed by CSF cytology; however, cytology suffers from low sensitivity and it is believed that many cases of LM go undiagnosed. Some studies have suggested the use of CA 15–3 in CSF (CA 15–3 CSF) to aid in the detection of LM. The purpose of this study was to compare the performance of CA 15–3 CSF to cytology for the detection and treatment monitoring of breast cancer LM. Methods CA 15–3 CSF requests between 2014 and 2016 were retrospectively reviewed. Fifty-two measurements from nine patients were from our health system and had corresponding CSF cytology measurements. Concordance between CA 15–3 CSF and CSF cytology was calculated. For patients with quantifiable CA 15–3 CSF, sequential determinations of CA 15–3 and cytology were compared over time to assess correlation of CA 15–3 CSF concentration and cytology with disease status. Results At the time of initial testing, seven of the nine patients (78%) had positive cytology. Two samples (22%) had quantifiable CA 15–3, both of which were also positive by cytology. The positive concordance between all cytology and CA 15–3 measurements was 9% (2/22), while negative concordance was 100% (30/30). Sequential CA 15–3 and cytology measurements showed a decrease in CA 15–3 that paralleled changes observed with cytology. Conclusions In this cohort of patients, CA 15–3 CSF performance was neither superior nor complementary to cytology for the detection of LM, nor did the combination of CA 15–3 CSF and cytology improve performance over cytology alone.

The peak cortisol response 30 or 60 minutes after cosyntropin [ACTH (1-24)] is regarded to be ≥18 μg/dL (500 nmol/L). This threshold is based on older immunoassays using polyclonal antibodies to detect cortisol. The use of more specific monoclonal antibody immunoassays or LC-MS/MS has been reported to provide a lower cutoff for a normal response. We compared the polyclonal antibody cortisol assay, Elecsys Cortisol I (Roche Diagnostic), whose peak cortisol response to ACTH 250 μg is ≥18 μg/dL (500 nmol/L), to two monoclonal antibody cortisol assays, Elecsys Cortisol II (Roche Diagnostic) and Access Cortisol (Beckman-Coulter), and LC-MS/MS in 55 patients undergoing testing for possible adrenal insufficiency. Using the Elecsys Cortisol I assay as the gold standard, all but 11 patients had a normal response at 30 or 60 minutes. Those patients were felt to have secondary adrenal insufficiency due to exogenous glucocorticoid therapy, endogenous glucocorticoid exposure, pituitary surgery, critical illness, or opioid use. ROC curves were used to determine thresholds for the other assays. A cortisol threshold of 14.5 μg/dL (400 nmol/L) would result in sensitivities and specificities of 100% and 94% for the Elecsys Cortisol II assay, 100% and 100% for the Access Cortisol assay, and 100% and 88% for LC-MS/MS. In conclusion, we recommend a new peak cortisol threshold of 14.5 μg/dL (400 nmol/L) after ACTH stimulation testing using one of these more highly specific cortisol assays. It will be important for clinicians to be aware of this new cutoff when evaluating patients for adrenal insufficiency.

Medullary thyroid carcinoma (MTC) is a rare but aggressive thyroid malignancy. Serum calcitonin measurement is considered the gold standard in the diagnosis and follow-up of MTC patients; however, there are a number of biological and analytical challenges that could negatively impact its usefulness. Procalcitonin (ProCT), a marker commonly used in the evaluation of sepsis, has been suggested to be a promising marker for the diagnosis and follow-up of MTC. Here, we summarize available studies in the clinical utility of ProCT in the evaluation of MTC. Overall findings indicate that addition of ProCT in the evaluation of MTC patient might complement current practice and in some cases might be superior to CT.

Over the past decade, there have been a rising number of clinically used tests that combine 2 or more biochemical or molecular assays, demographics, and clinical information into an algorithm to generate diagnostic, prognostic, or predictive information for a specific disease. The concept of multianalyte analyses is relatively new in the field of laboratory medicine. Dating back to the 1980s, prenatal screening for fetal abnormalities, such as Down syndrome, by use of maternal biomarkers is among the pioneer tests that use algorithmic analyses for risk assessment. Yet, the number of multianalyte algorithms used clinically remains modest. The American Medical Association provides current procedural terminology (CPT)8 codes for 20 multianalyte assays with algorithmic analyses (MAAAs.) Among these, 9 consist of biochemical markers detected by immunoassay or mass spectrometry, with or without other clinical information; 11 use molecular genetics markers; and 1 is for generic use. In this Q&A, we refer to multivariable tests with risk scores as MAAAs, although not all of them have an associated MAAA CPT code. Generally speaking, MAAAs aim at improving diagnostics for diseases in which single biomarkers have limited clinical validity. The Prostate Health Index (Beckman Coulter) and the 4Kscore® (GenPath) exemplify some of these strategies for prostate cancer detection. Likewise, multianalyte analyses such as the Risk of Ovarian Malignancy Algorithm (ROMA®) and OVA1® and its second-generation OVERATM (Vermillion Inc.) improve upon the suboptimal performance of the tumor marker CA125 in the differential diagnosis and likelihood of ovarian carcinoma in women presenting with a pelvic mass. While both have Food and Drug Administration (FDA) clearance, ROMA is a nonproprietary algorithm cleared on various commercial immunoassays (Fujirebio Diagnostics, Inc.; Abbott Laboratories; Roche Diagnostics). Early identification of acute kidney injury is another area in which an FDA-approved multianalyte test, Nephrocheck® (Astute Medical), …

Context: Measurement of thyroglobulin (Tg) by mass spectrometry (Tg-MS) is emerging as a tool for accurate Tg quantification in patients with anti-Tg autoantibodies (TgAbs). Objective: The objective of the study was to perform analytical and clinical evaluations of two Tg-MS assays in comparison with immunometric Tg assays (Tg-IAs) and Tg RIAs (Tg-RIAs) in a cohort of thyroid cancer patients. Methods: A total of 589 samples from 495 patients, 243 TgAb−/252 TgAb+, were tested by Beckman, Roche, Siemens-Immulite, and Thermo-Brahms Tg and TgAb assays, two Tg-RIAs, and two Tg-MS assays. Results: The frequency of TgAb+ was 58%, 41%, 27%, and 39% for Roche, Beckman, Siemens-Immulite, and Thermo-Brahms, respectively. In TgAb− samples, clinical sensitivities and specificities of 100% and 74%–100%, respectively, were observed across all assays. In TgAb+ samples, all Tg-IAs demonstrated assay-dependent Tg underestimation, ranging from 41% to 86%. In TgAb+ samples, the use of a common cutoff (0.5 ng/mL) for the Tg-M...

Objective Thyroglobulin (Tg) quantitation by immunometric assays is compromised by anti-thyroglobulin antibodies (TgAbs), potentially resulting in falsely low Tg concentrations. TgAb screening is recommended when measuring Tg, but current TgAb immunoassays do not detect all possible TgAbs in circulation. We assessed the impact of a change in TgAb assay on apparent disease status of patients with differentiated thyroid carcinoma (DTC). Methods Patients seen at the Mayo Clinic, Rochester, Minnesota, for follow-up of DTC, who had been tested using 2 different TgAb assays (Beckman Access and Roche Elecsys) were identified. Electronic medical records were reviewed to evaluate any impact the change in TgAb assay had on clinical disease status assessment and follow-up. Results A total of 1,457 patients were tested using both assays. A change in TgAb status was found in 124 (8.5%) patients; a total of 117 patients who were TgAbnegative on the Beckman assay became TgAb-positive with the Roche assay. Additional testing was performed in 5 of these patients. Seven patients previously considered TgAb-positive were now TgAb-negative. In all 7 cases, physicians documented that they considered these patients now to be truly TgAb-negative and free of disease. Conclusion Discrepancies in TgAb status are seen when using different TgAb assays. Relying on Tg and TgAb measurements to determine disease status may lead to underestimation of residual cancer. A multimodal (clinical, biochemical, and radiologic) approach to follow up on patients with DTC should be continued, pending the development of Tg quantitation methods that are highly sensitive and not affected by TgAb interference. (Endocr Pract. 2014;20:1032-1036)

BACKGROUND The objective of this study is the validation and proof of clinical relevance of a novel electrochemiluminescence immunoassay (ECLIA) for the determination of serum calcitonin (CT) in patients with medullary thyroid carcinoma (MTC) and in different diseases of the thyroid and of calcium homeostasis. METHODS This was a multicenter prospective study on basal serum CT concentrations performed in 9 US and European referral institutions. In addition, stimulated CT concentrations were measured in 50 healthy volunteers after intravenous calcium administration (2.5 mg/kg bodyweight). RESULTS In total, 1929 patients and healthy controls were included. Limits of blank, detection, and quantification for the ECLIA were 0.3, 0.5, and 1 ng/L, respectively. Highest intra- and interassay coefficients of variation were 7.4% (CT concentration, 0.8 ng/L) and 7.0% (1.1 ng/L), respectively. Medians (interval) of serum CT concentrations in 783 healthy controls were 0.8 ng/L (97.5th percentile in 33%/4.7%, 18.5%/10%, and 8.3%/12%, females/males, respectively. Peak serum CT concentrations were reached 2 min after calcium administration (161.7 and 111.8 ng/L in males and females, respectively; P < 0.001). CONCLUSIONS Excellent analytical performance, low interindividual variability, and low impact of confounders for increased CT concentrations in non-MTC patients indicate that the investigated assay has appropriate clinical utility. Calcium-stimulated CT results suggest good test applicability owing to low interindividual variability.

The purpose of this study was to define an appropriate nadir growth hormone (nGH) cutoff for patients with acromegaly in remission using the Access Ultrasensitive human growth hormone (hGH) assay (Beckman Coulter, Brea, CA).This cross-sectional study included 55 acromegalic subjects and 41 healthy adult volunteers. All subjects underwent oral glucose tolerance testing (OGTT) for growth hormones (GHs). An optimal cutoff for nGH for patients with active disease versus those in remission was determined using receiver-operating curve analysis.The nGH of 0.53 ng/mL revealed a sensitivity of 97% (95% confidence interval [CI], 83-100%) and a specificity of 100% (95% CI, 82-100%). All 22 patients with acromegaly in remission suppressed GH to1 ng/mL, 20/22 (91%) suppressed to0.4 ng/mL, and 19/22 (86%) of subjects suppressed to0.3 ng/mL (the maximum nGH measured in our healthy volunteer group).When using the Access Ultrasensitive hGH assay for OGTT, a cutoff of 0.53 ng/mL was found to most accurately differentiate patients with acromegaly in remission from those with active disease.

In vitro studies have demonstrated that the PAX8/PPARγ fusion protein (PPFP), which occurs frequently in follicular thyroid carcinomas (FTC), exhibits oncogenic activity. However, paradoxically, a meta-analysis of extant tumor outcome studies indicates that 68% of FTC-expressing PPFP are minimally invasive compared to only 32% of those lacking PPFP (χ 2 = 6.86, P = 0.008), suggesting that PPFP favorably impacts FTC outcomes. In studies designed to distinguish benign thyroid neoplasms from thyroid carcinomas, the previously identified tumor suppressor miR-122, a major liver micro-RNA (miR) that is decreased in hepatocellular carcinoma, was increased 8.9-fold (P < 0.05) in all FTC versus normal, 9.2-fold in FTC versus FA (P < 0.05), and 16.8-fold (P < 0.001) in FTC + PPFP versus FTC – PPFP. Constitutive expression of PPFP in the FTC-derived cell line WRO (WRO-PPFP) caused a 5-fold increase of miR-122 expression (P < 0.05) and a striking 5.1-fold reduction (P < 0.0001) in tumor progression compared to WRO-vector cells in a mouse xenograft model. Constitutive expression of either miR-122 or a dominant-negative PPARγ mutant in WRO cells was less effective than PPFP at inhibiting xenograft tumor progression (1.8-fold [P < 0.001] and 1.7-fold [P < 0.03], respectively). PPFP-induced up-regulation of miR-122 expression was independent of its known dominant-negative PPARγ activity. Up-regulation of miR-122 negatively regulates ADAM-17, a known downstream target, in thyroid cells, suggesting an antiangiogenic mechanism in thyroid carcinoma. This latter inference is directly supported by reduced CD-31 expression in WRO xenografts expressing PPFP, miR-122, and DN-PPARγ. We conclude that, in addition to its apparent oncogenic potential in vitro, PPFP exhibits paradoxical tumor suppressor activity in vivo, mediated by multiple mechanisms including up-regulation of miR-122 and dominant-negative inhibition of PPARγ activity.

Introduction Varied presentations of vitamin B12 (B12) deficiency include hematologic (megaloblastic anemia) and neurologic (myelopathy, peripheral neuropathy). Delayed recognition and treatment may have serious consequences. Assessing B12 status can be challenging due to diverse laboratory assays and thresholds, resulting in a wide range of reported prevalence of B12 deficiency from 3-26%. Comorbidities may also spuriously elevate or suppress B12 levels. Methylmalonic acid (MMA) level, often used as a companion test to assess for B12 deficiency, may also be affected by differing laboratory thresholds and other medical comorbidities, such as renal dysfunction. Our institutional approach to B12 assessment, termed the pernicious anemia (PA) cascade, consists of reflexive testing to 1) document low B12 stores (B12 levels with or without MMA), and 2) diagnose pernicious anemia (intrinsic factor binding antibody [IFBA] with or without gastrin assay). In this study, our objectives were: (1) assess the usefulness of our B12 testing algorithm and associated laboratory thresholds for identifying B12 deficiency, and (2) evaluate clinical follow-up of test results as part of a quality project. Methods In this retrospective study, adult (age ≥18 years) inpatients who had B12 testing from 2007 to 2013 were identified. Medical records for those patients with B12 levels 150-400 ng/L were reviewed. Data abstracted included patient demographics, indication for B12 testing, B12 levels, results for MMA, IFBA, gastrin, serum creatinine, complete blood count, and clinical outpatient follow-up. The PA cascade algorithm is as follows: 1) for B12 0.40 nmol/mL, then IFBA is performed. Reference range for B12 is 180-914 ng/L. Patients were determined to be B12 deficient if B12 level was Results Records of 326 patients (150 female) were reviewed. Indications for B12 testing were: hematologic, 175 patients (53.7%); neurologic, 127 patients (39.0 %), psychiatric, 18 patients (5.5%); other, 4 patients (1.2%). Fifty-nine of 326 (18.1%) patients were B12 deficient, of whom 17 of 59 (28.8%) had PA. There were 54 cases of elevated MMA, >0.40 nmol/mL, of which 30 cases had mildly elevated MMA, >0.40 nmol/mL and ≤0.60 nmol/mL, considered to be the MMA "gray zone". Thirty-two of the total 326 patients had serum creatinine ≥2.0 mg/dL, of which 23 patients also had elevated MMA. Elevated MMA in 13 of these 23 patients was more likely due to renal dysfunction than to B12 deficiency. B12 testing results were not mentioned in hospital discharge summaries for 173 patients, including 8 patients with B12 deficiency. For 22 B12-deficient patients, there was no documentation of B12 replacement. Conclusions The PA cascade detected B12 deficiency in a significant number of inpatients with low-normal B12 levels that might have otherwise been missed; 28.8% of this group had PA for whom long-term B12 replacement is indicated. As treatment for B12 deficiency is inexpensive, non-toxic, and non-invasive, it is reasonable to evaluate B12 status by cascade testing which may provide additional diagnostic data beyond B12 level. Notable clinical practice findings from this study include the lack of B12 results in 173 of 326 discharge summaries, and no record of B12 supplementation in 22 of 59 patients with B12 deficiency. These gaps in documentation and follow-up may be associated with the relatively long turnaround time of MMA testing. Efforts at improving documentation, communication, and treatment of B12 deficiency are ongoing. Disclosures No relevant conflicts of interest to declare.

Genetic variability in drug-metabolizing enzymes and signaling pathways affects chemotherapy-related toxicity and treatment outcome in cancer. In breast and colorectal cancer, polymorphisms in metabolic enzymes involved in tamoxifen and irinotecan therapies has led the U.S. Food and Drug Administration to address genetic factors relevant to patient consideration of treatment with these compounds. Tamoxifen therapeutic failure in breast cancer has been associated with reduced CYP2D6 activity due to inefficient activation of tamoxifen. Irinotecan toxicity in colorectal cancer is more common in patients with reduced-activity UGT1A alleles, resulting in excessive exposure to the potent SN-38 metabolite. In colorectal and lung cancers, somatic mutations in the epidermal growth factor receptor and downstream signaling molecules have been associated with the therapeutic outcome of epidermal growth factor receptor-directed therapies. This review discusses the current knowledge regarding the utility of single gene—UGT1A1, CYP2D6, EGFR, and KRAS—or multigene analysis, for optimizing breast, colorectal, and lung cancer therapy. Current advances in these areas highlight how pharmacogenetics help personalized decision-making for patient management.

Genetic variability in drugmetabolizing enzymes affects the toxicity and efficacy of many compounds, including the chemotherapeutic agents irinotecan and tamoxifen. The correlation of clinical response to polymorphisms in enzymes associated with metabolism of these two drugs has led to the recommendation that patients who receive them undergo genotyping analysis. Irinotecan toxicity in patients who have colorectal cancer has been linked to reduced activity of uridine diphosphate-glucuronyltransferase 1A1 (UGT1A1). Reduced cytochrome P450 (CYP) 2D6 activity leads to therapeutic failure of tamoxifen in the prevention and treatment of breast cancer, as a result of absence of conversion of the prodrug to its active forms. This article discusses current knowledge of the usefulness of UGT1A1 and CYP2D6 genotyping in the context of cancer chemotherapy and highlights the need for additional studies to clarify the many issues remaining.

The objective of this study was to assess the diagnostic accuracy of C-reactive protein (CRP), procalcitonin (PCT), and cellular immune markers levels in sepsis. This was a prospective observational study in adult intensive care unit (ICU) patients, between 2012 and 2014. The 8-color flow cytometric biomarker panel included CD64, CD163, and HLA-DR. Index test results were compared with sepsis, using receiver operating characteristic curve analyses. Multivariate logistic regression assessed the relationship of sets of markers with the probability of sepsis. Of 219 enrolled patients, 120 had sepsis. C-statistic was the highest for CRP (0.86) followed by neutrophil CD64 expression (0.83), procalcitonin (0.82), and Acute Physiology and Chronic Health Evaluation (APACHE) IV (0.72). After adjustment for APACHE IV, the combination of CRP, PCT, and neutrophil CD64 measure remained a significant predictor of sepsis with an excellent AUC (0.90). In a targeted ICU population at increased risk of sepsis, CRP, PCT, and neutrophil CD64 combined improve the diagnostic accuracy of sepsis.

Objective Our aim was to identify the frequency and possible clinical and analytical factors leading to “falsely” elevated insulin-like growth factor-1 (IGF-1). Methods We performed a retrospective review of patients with IGF-1 concentrations above the reference interval. They were selected from a database of patients who had consecutive IGF-1 measurements between the years 2007-2010. Results Out of 2,747 unique patients, 117 (4%) were found to have IGF-1 concentrations above the reference interval that were considered false-positives following a review of the clinical data. There was no relationship between the percentage of increase in IGF-1 and age, sex, body mass index (BMI), comorbidities, medication use, gonadal status, baseline growth hormone (GH), or insulinlike growth factor binding protein-3 (IGFBP-3) concentrations. An abnormal IGF-1 concentration led to performance of an oral glucose tolerance test (OGTT) for GH suppression in 21 of 117 patients (18%) and repeat IGF-1 measurements in 52 patients (44%). In 34 of 52 patients (65%) with a median follow-up of 36 months, the subsequent IGF-1 concentration was within the reference interval. Conclusion Discovery of “falsely” elevated IGF-1 concentrations may lead to unnecessary testing and physician visits.Although the cause of the “falsely” elevated IGF-1 concentrations during the study period remains to be elucidated, it appears they are caused by a combination of high biological variability and method-specific assay performance issues. Clinicians should consider retesting patients with potentially spurious IGF-1 elevations after some time interval before embarking on more extensive investigations. (Endocr Pract. 2014;20:421-426)

Tamoxifen is used in the treatment of estrogen receptor (ER) positive breast cancers and in breast cancer prophylaxis for high-risk women [1, 2]. The benefits of tamoxifen are apparent, as the drug successfully reduces rates of recurrence and mortality in patients with ER-positive breast cancer [3]. However, these benefits are not without risk; adverse effects range from hot flashes to endometrial cancer and life-threatening thromboembolism [2]. The use of genetic information to predict response to tamoxifen therapy holds the potential to improve therapeutic outcome while minimizing toxicity. This chapter will discuss aspects of tamoxifen pharmacology and pharmacogenetics, with case studies to explore the clinical utility of genotype testing in tamoxifen therapy.

Calcitonin (CT) is the main medullary thyroid carcinoma (MTC) tumor marker. However, it has several limitations, including a concentration-dependent biphasic half-life, sensitivity to rapid in vitro degradation, and the presence of different isoforms/fragments. Procalcitonin (PCT), the prohormone of calcitonin, is free of these limitations but is currently used only as a sepsis marker.The objective of the study was to determine whether PCT is suited as a MTC tumor marker by comparing the diagnostic performance of PCT with that of CT in MTC.PCT and CT were measured in a total of 835 subjects, including normal volunteers (n = 197) and patients with active-MTC (n = 91), cured-MTC (n = 42), neuroendocrine tumors (n = 225), mastocytosis (n = 48), follicular cell-derived thyroid carcinoma (cured = 120, persistent/recurrent = 55), and benign thyroid disease (n = 57).PCT levels were significantly higher in the active-MTC patients (mean 126.4 ng/ml) than the cured-MTC patients (mean0.1 ng/ml). The overall concordance between the two markers was 95.7% (kappa = 0.81). Receiver-operating characteristic curve analysis showed no significant difference in diagnostic performance between CT and PCT. PCT's diagnostic sensitivity and specificity were 91 and 96%, respectively. The corresponding values for CT were 99 and 98%. Analyte stability studies showed that CT is very unstable in vitro with a decrease of 35-50% from the original value 24 h after the blood draw, whereas PCT levels did not significantly change during this time.A strong correlation was observed between PCT and CT levels in patients with MCT. Given PCT's greater analytical stability, we conclude that it represents a promising complementary MTC tumor marker.

Context: The initial diagnosis of pheochromocytoma relies on plasma fractionated metanephrines levels. Normal levels exclude pheochromocytoma, but positive tests have a low positive predictive value due to the disease’s rarity. Objectives: The objective of the study was to evaluate three approaches to distinguish between true-positive and false-positive tests: 1) increased cutoff for plasma fractionated metanephrines, 2) measurement of serum/plasma chromogranin A (CGA), and 3) urine fractionated metanephrine testing. Design: We studied retrospectively all Mayo Clinic patients with positive plasma fractionated metanephrine tests over a 15-month period and determined their final diagnosis based on histology, imaging, additional biochemical tests, and more than 1 yr follow-up. For a subgroup, urine fractionated metanephrine results were available. All original plasma samples were retested for CGA. Results: Of 140 patients, 40 had a chromaffin tumor confirmed and 100 excluded, indicating a positive predictive value of plasma fractionated metanephrines of 28.6%. Increasing the threshold for a positive test improved specificity to 98% but missed eight cases (20%). Incorporation of urine fractionated metanephrine testing as follow-up test achieved 80% specificity and 91% sensitivity. The corresponding figures for CGA were 71 and 87% for all patients and 89 and 87% when patients taking proton pump inhibitors were excluded. Conclusions: Unless plasma fractionated metanephrines levels are elevated more than 4-fold above the upper limit of normal, patients with a positive plasma fractionated metanephrines test should be evaluated with urine fractionated metanephrines and serum/plasma CGA assays before being subjected to imaging or invasive diagnostic tests.

Low awareness, late recognition and delayed treatment of sepsis are still common. CD64 is a marker of the innate immune response upregulated in sepsis. The primary goal of this prospective, double-blind study was to compare the diagnostic accuracy of neutrophil CD64 and other cellular markers, along with C-reactive protein (CRP) and procalcitonin (PCT) levels, in early sepsis.

Dear Editor: Approximately 25% of thyroid cancer patients have circulating antithyroglobulin autoantibodies (anti-TgAB), which can cause false-low interference in Tg assays (1). It is therefore recommended that all Tg measurements are accompanied by TgAB testing (1). The Beckman-Coulter Access Tg- and TgAB assays have become perhaps the most widely used assay combination for thyroid cancer follow-up in the United States, because they run on the same automated instrument and they are more sensitive than most alternative Tg/TgAB assays. Unfortunately, Beckman-Coulter has recently indicated that their TgAB assay will be unavailable for the foreseeable future, necessitating a switch to other TgAB assays to accompany Tg testing. Such a change has a high risk of interfering with patient management. Different TgAB assays show at best a moderate numerical agreement with each other, have different detection sensitivities, and have different cutoffs for TgAB positivity (2–4). We have therefore performed a comparison study of the Beckman-Coulter TgAB assay with three other automated TgAB assays: Roche Elecsys TgAB, Siemens-Centaur TgAB, and Siemens-Immulite TgAB. As these assays are primarily marketed for the diagnosis of autoimmune thyroid disease, the manufacturer-provided diagnostic cutoffs are not optimized for the detection of interference in Tg assays. Therefore, we first determined optimal cutoffs for these assays by comparing them with the Beckman-Coulter assay in 100 archival patient samples. Next, we performed a clinical validation of these cutoffs in 130 samples from 113 Mayo Clinic patients. These samples were selected to include patients with (43 patients with 51 samples) and without (70 patients with 79 samples) definitive persistent/recurrent disease (clinical or imaging proven) (see Supplementary Methods; Supplementary Data are available online at www.liebertonline.com/thy). We found poor numerical agreement between the Beckman-Coulter assay and the other TgAB assays, but receiver-operating characteristics (ROC) curve analysis, using the Beckman-Coulter TgAB results as the “gold standard” (negative

Background: There is limited data on the utility of the percentage of lens culinaris agglutininreactive α-fetoprotein (AFP-L3%) measured on the new μTASWako i30 Immunoanalyzer for the diagnosis of early stage HCC in the U.S. population. The utility of AFP, AFP-L3% or des-γ-carboxy prothrombin (DCP) for predictingHCC recurrence after liver transplantation is also unknown. Aims: To 1) determine the sensitivity and specificity of AFP, AFP-L3%, and DCP for the diagnosis of early stage HCC; and 2) evaluate the utility of AFP, AFP-L3% and DCP in predicting HCC recurrence after orthotopic liver transplantation (OLT). Methods: Three hundred and thirteen HCC patients and 307 non-HCC controls with end-stage liver disease who were transplanted at Mayo Clinic, Rochester, MN and Jacksonville, FL between 2000 2008 and had serum samples available for biomarker testing were included in the study. Demographic and clinical information were abstracted from the medical record. AFP, AFP-L3% and des-γ-carboxy prothrombin (DCP) assays were performed on the μTASWako i30 Immunoanalyzer. Receiver operating characteristic (ROC) curves were generated to determine the sensitivity and specificity of the biomarkers for diagnosis of HCC. Predictors of HCC development and HCC recurrence were analyzed using the Logistic regression model. Results: AFP had the best area under the ROC curve (0.75, 95%CI 0.72-0.78) for diagnosis of early stage HCC, followed by AFP-L3% (0.63, 95% CI 0.60-0.66) and DCP (0.46, 95%CI 0.43-0.49). The optimum cut-off value of AFP was 9.4 ng/ml with the sensitivity of 62.6% and specificity of 80% and of AFP-L3% was 15.8% with a sensitivity of 30.1% and specificity of 85.1%. AFP and AFP-L3% were independently associated with early stage HCC. Every 10 ng/mL increase in AFP value and every 10% increase in AFP-L3% value were associated with a 36.6% and 43.0% increased risk for HCC diagnosis (OR=1.37, 95%CI 1.20-1.56 for AFP, p,0.0001,and OR 1.43, 95% CI 1.18-1.58 for AFP-L3%, p,0.0001). Of the 313 HCC patients, 301 (96.2%) patients were treated with transarterial chemoembolization (TACE) prior to transplantation. Forty-seven (15%) patients had HCC recurrence after transplant (median time for recurrence was 18.4 months). The post-TACE pre-OLT AFP-L3% was significantly associated with HCC recurrence after OLT. Every 10% increase in post-TACE AFP-L3 was associated with a 48.2% increased risk of HCC recurrence after OLT (OR=1.48, 95% CI 1.11 to 1.97, p=0.007). AFP, AFP-L3% and DCP at the time of HCC diagnosis were not associated with HCC recurrence after OLT. Conclusions: AFP-L3% is potentially useful in predicting HCC recurrence after liver transplantation in US patients. Validation of these results in additional cohorts is needed.