Search

Adult and pediatric endocrinology and oncology often requires measuring serum estrogens and testosterone at very low concentrations. Conventional immunoassay methods often lack the required performance to meet this analytical need, and mass spectrometry techniques must be employed. Our aim was to develop a sensitive HPLC-MS/MS assay for both estradiol (E2) and testosterone (Te) in serum, utilizing commercially available calibrators and without the need for chemical derivatization. Serum samples, after the addition of an internal standard, are combined with a hexane:ethyl acetate extraction solution. The samples are vortexed, and the organic layer is decanted into a clean sample tube and evaporated to dryness under a stream of nitrogen. The samples are reconstituted in a water:methanol solution and separated chromatographically using a reversed-phase HPLC column. Subsequent mass spectrometry is performed using both positive ion mode for Te and negative ion mode for E2.

Dysgeusia is a common but understudied complication in patients undergoing autologous hematopoietic cell transplantation (auto-HCT). We assessed the feasibility of using chemical gustometry (CG) to measure dysgeusia and explored its associations with symptom burden, nutrition, chemotherapy pharmacokinetics (PK), and the oral microbiome.We conducted a single-center, prospective feasibility study (NCT03276481) of patients with multiple myeloma undergoing auto-HCT. CG was performed longitudinally testing five flavors (sweet, sour, salty, bitter, umami) to calculate a total taste score (maximum score, 30). We measured caloric intake and patient-reported symptoms, assessing their correlation with oral microbiota composition and salivary and blood melphalan PK exposure.Among all 45 patients, 39 (87%) completed at least four (60%) and 22 (49%) completed all six CG assessments. Median total CG scores remained stable over time but were lowest at day +7 (27, range 24-30) with recovery by day +100. Symptom burden was highest by day +10 (area under the curve, 2.9; range, 1.0-4.6) corresponding with the lowest median overall caloric intake (1624 kcal; range, 1345-2267). Higher serum/salivary melphalan levels correlated with higher patient-reported dysgeusia and lower caloric intake. Oral microbiota α-diversity was stable early and increased slightly by day +100.Assessment of dysgeusia by CG is feasible after auto-HCT. Most dysgeusia, symptom burden, and lowest caloric intake occurred during the blood count nadir. Higher melphalan concentrations correlated with more dysgeusia and poorer caloric intake. Future studies will aim to modulate melphalan exposure by PK-targeted dosing and characterize patient taste preferences to personalize diets for improved nutritional intake.Taste changes after cancer treatments are very common. We used chemical gustometry (taste testing) to study taste changes and to better understand why patients with multiple myeloma experience this symptom after autologous hematopoietic cell transplantation. We found that taste testing was feasible, taste changes peaked when blood counts were lowest, and most patients recovered their taste by 100 days after transplantation. Taste changes correlated with lower food intake and with higher levels of chemotherapy in the body. Future work will focus on using personalized chemotherapy doses to reduce taste changes and to match patients' individual taste preferences with their diets.

Antiepileptic drugs (AEDs) are a diverse group of pharmacological agents used in the treatment of epileptic seizures. Over the past several decades some new AEDs, including lamotrigine (LTG), levetiracetam (LVA), oxcarbazepine (OXC), topiramate (TOP), and zonisamide (ZNS), have become widely used. This chapter describes a very simple and rapid liquid chromatography-tandem mass spectrometry method for simultaneous quantitation of LVA, ZNS, LTG, TOP, and MHD in human serum. The method requires a very small amount of serum (50 μL) for multiple drug measurements and has a total analysis time of 4 min that makes it well suited for routine clinical analysis of several drugs simultaneously. The imprecision (CVs) measured at various concentrations across the analytical measurement range (AMR) are less than 7% for all analytes. The AMR for each analyte is as follows: LVA (1-100 μg/mL), ZNS (0.8-80 μg/mL), TOP (0.5-50 μg/mL), and 0.6-60 μg/mL for LTG and MHD.

Methotrexate (MTX) is a folic acid antagonist that is widely used as an immunosuppressant and chemotherapeutic agent. After high-dose administration of MTX serum levels must be monitored to determine when to administer leucovorin, a folic acid analog that bypasses the enzyme inhibition caused by MTX and reverses its toxicity. We describe a rapid and simple turbulent flow liquid chromatography (TFLC) method implementing positive heated electrospray ionization (HESI) for the accurate and precise determination of MTX, 7-hydroxymethotrexate (7-OH MTX), and 4-amino-4-deoxy-N(10)-methylpteroic acid (DAMPA) concentrations in serum. MTX is isolated from serum samples (100 μL) after protein precipitation with a methanolic solution containing internal standard (MTX-D3) followed by centrifugation. The supernatant is injected into the turbulent flow liquid chromatography which is followed by electrospray positive ionization tandem mass spectrometry (TFLC-ESI-MS/MS) and quantified using a six-point calibration curve. For MTX, 7-OH MTX, and DAMPA the assays were linear from 20 to 1000 nmol/L. Dilutions of 10-, 100-, and 1000-fold were validated giving a clinically reportable range of 20 to 1.0 × 10(6) nmol/L. Within-day and between-day precisions at concentrations spanning the analytical measurement ranges were less than 10 % for all three analytes.

Patients with significant proteinuria represent a unique population with respect to vitamin D status due to the urinary losses of vitamin D-binding protein (DBP) to which99 % of circulating 25-hydroxy vitamin D (25(OH)D) is bound. Low serum concentrations of 25(OH)D have been found in children and adults with nephrotic syndrome (NS). However, previously described assays developed to quantify the magnitude of urinary loss are technically challenging. This chapter describes a simple and sensitive method to quantify 25(OH)D2 and 25(OH)D3 in urine specimens in a single analytical LC-MS/MS analysis. This assay is more sensitive than previously described radioimmunoassays and offers the ability to quantitate both forms of 25-hydroxy vitamin D. The assay involves no chemical derivitization, has a linear measurement range of 20-1500 pg/mL and displays imprecision (CVs) below 7 % at various concentrations across the analytical measurement range.