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Background: The reference change value (RCV) is calculated by combining the within-subject biological variation (CVI) and local analytical variation (CVA). These calculations do not account for the variation seen in preanalytical conditions in routine practice or CVI in patients presenting for treatment. As a result, the RCVs may not reflect routine practice or align with clinicians' experiences. We propose a novel RCV approach based on routine patient data that is potentially more clinically relevant., Methods: This study used the refineR algorithm to determine RCVs using serial patient data extracted from a local Laboratory Information System (LIS). The model was applied to biomarkers with a range of result ratio distributions varying from normal to log-normal. Results were compared against conventional formula-based RCVs using CVI estimates from a state-of-the-art biological variation study. Monte Carlo simulations were also used to validate the LIS data approach., Results: The RCVs estimated from LIS data were: 11-deoxycortisol (men): -70%/+196%, 17-hydroxyprogesterone (men): -49%/+100%, albumin: -10%/+11%, androstenedione (men): -47%/+96%, cortisol (men): -54%/+51%, cortisone (men): -32%/+51%, creatinine: -16%/+14%, phosphate (women): -23%/+29%, phosphate (men): -27%/+29%, testosterone (men): -38%/+60%. The formula-based RCV estimates showed similar but slightly lower results, and the Monte Carlo simulations confirmed the applicability of the new approach., Conclusions: RCVs may be estimated from patient results without prior assumptions about the shape of the ratios between serial results. Laboratories can determine RCVs based on local practice and population., (© Association for Diagnostics & Laboratory Medicine 2024.)

Background: Biological variation (BV) data may be used to develop analytical performance specifications (APS), reference change values (RCV), and support the applicability of population reference intervals. This study estimates within-subject BV (CVI) for several endocrine biomarkers using 3 different methodological approaches., Methods: For the direct method, 30 healthy volunteers were sampled weekly for 10 consecutive weeks. Samples were analyzed in duplicate for 17-hydroxyprogesterone (17-OHP), androstenedione, cortisol, cortisone, estradiol, follicle-stimulating hormone (FSH), luteinizing hormone (LH), sex hormone-binding globulin (SHBG), and testosterone. A CV-ANOVA with outlier removal and a Bayesian model were applied to derive the CVI. For estradiol, FSH and LH, only the male subgroup was included. In the indirect method, using the same analytes and groups, pairs of sequential results were extracted from the laboratory information system. The total result variation for individual pairs was determined by identifying a central gaussian distribution in the ratios of the result pairs. The CVI was then estimated by removing the effect of analytical variation., Results: The estimated CVI from the Bayesian model (μCVP(i)) in the total cohort was: 17-OHP, 23%; androstenedione, 20%; cortisol, 18%; cortisone, 11%; SHBG, 7.4%; testosterone, 16%; and for the sex hormones in men: estradiol, 14%; FSH, 8%; and LH, 26%. CVI-heterogeneity was present for most endocrine markers. Similar CVI data were estimated using the CV-ANOVA and the indirect method., Conclusions: Similar CVI data were obtained using 2 different direct and one indirect method. The indirect approach is a low-cost alternative ensuring implementation of CVI data applicable for local conditions., (© American Association for Clinical Chemistry 2022.)

Objective: Liquid chromatography-mass spectrometry (LC-MS/MS) offers superior analytical specificity compared to immunoassays, but is not available in many regions and hospital due to expensive instrumentation and tedious sample preparation. Thus, we developed an automated, high-throughput LC-MS/MS assay for simultaneous quantification of 10 endogenous and synthetic steroids targeting diseases of the hypothalamo-pituitary-adrenal-axis and gonads., Methods: Deuterated internal standards were added to 85µl serum and processed by liquid-liquid-extraction. Cortisol, cortisone, prednisolone, prednisone, 11-deoxycortisol, dexamethasone, testosterone, androstenedione and progesterone were resolved by ultra-high pressure chromatography on a reversed-phase column in 6.1 minutes, and detected by triple-quadrupole MS. The method was used to assess steroid profiles in women with Addison's disease (AD, n=156) and blood donors (BD, n=102)., Results: Precisions ranged 4.5-10.1% RSD, accuracies 95-108%, and extraction recoveries 60-84%. The method was practically free of matrix effects and robust to individual differences in serum composition. Most postmenopausal AD women had extremely low androstenedione below 0.14 nmol/L and median testosterone 0.15 nmol/L [interquartile range 0.00-0.41], considerably lower than postmenopausal BD (1.28 nmol/L [0.96-1.64] and 0.65 nmol/L [0.56-1.10], respectively). AD women in fertile years had androstenedione 1.18 nmol/L [0.71-1.76] and testosterone 0.44 nmol/L [0.22-0.63], approximately half of levels found in BD of corresponding age., Conclusion: This LC-MS/MS assay provides highly sensitive and specific assessments of glucocorticoids and androgens with low sample volumes, and is suitable for endocrine laboratories and research. Its utility was demonstrated in a large cohort of women with AD, and the data suggest that women with AD are particularly androgen deficient after menopause.