Background: We compared the rates of intraoperative parathyroid hormone (PTH) decline using the Siemens Immulite® Turbo PTH and Roche Elecsys® short turnaround time PTH assays in 95 consecutive surgical patients to investigate analytical and turnaround time (TAT) differences between the tests performed in the operating room (OR) vs the central clinical chemistry laboratory (CCL). Methods: Serial blood samples from 95 patients undergoing parathyroidectomy were collected and measured using the 2 immunoassays. Specimens from the first 15 patients were measured simultaneously in the OR and CCL and used for the TAT study. In addition to 2 baseline samples, specimens were collected at 5, 10, and 15 min (for some patients, >15 min) after parathyroidectomy. Results: In the TAT study, a significant difference was observed (OR median 20 min vs CCL median 27 min; P < 0.05). Of the 95 patient series, slower rates of parathyroid hormone decrease were observed in approximately 20% of the patients when comparing the Roche with the Immulite immunoassay. Conclusions: There was a slightly longer TAT in the CCL compared with running the assay directly within the OR (median difference of approximately 7 min). For a majority of the patients, both methods showed equivalent rates of PTH decline; however, for approximately 20% of the patients, there was a slower rate of PTH decline using the Roche assay.

Fat-soluble vitamins are measured to identify deficiencies that may lead to rickets, osteomalacia, night blindness, and reversible motor and sensory neuropathies. We present a rapid liquid chromatography–mass spectrometry (LC-MS/MS) method that simultaneously measures 25-hydroxyvitamin D₃ (25[OH]D₃), epi-25(OH)D₃, 25(OH)D₂, vitamin A, α-tocopherol, and γ-tocopherol. We mixed 100 µL serum with internal standard and extracted it by using supported liquid extraction plates. Reconstituted specimens were analyzed by LC-MS/MS with a 10-minute gradient. The method was linear, covering physiological levels with r² > 0.99, and the total precision was less than 15% at all quality control levels. The lower limit of the measuring intervals for 25(OH)D₃, epi-25(OH)D₃, 25(OH)D₂, vitamin A, α-tocopherol, and γ-tocopherol were 4 ng/mL, 4 ng/mL, 4 ng/mL, 1 µg/dL, 0.2 µg/mL, and 0.2 µg/mL, respectively, with coefficient of variation of 20% or less. Recoveries were between 92% and 111% for National Institute of Standards and Technology reference materials and 81% and 122% for spike-recovery studies. Comparison studies for vitamin D total, vitamin A, and α-tocopherol demonstrated slopes between 1.04 and 1.11 and r² between 0.94 and 0.96. Minimal matrix effect was observed for all analytes. We developed and validated a rapid LC-MS/MS method for the simultaneous measurement of 25(OH)D₃, epi-25(OH)D₃, 25(OH)D₂, vitamin A, α-tocopherol, and γ-tocopherol.

Organic acidurias, a subgroup of inborn errors of metabolism (IEMs), are characterized by the accumulation of non-amine-containing, low-molecular-weight organic acids (OAs) in urine and/or plasma due to defects in specific metabolic pathways. Early diagnosis can be critical to enable timely intervention to prevent irreversible neurological injury or death. Therefore, urine organic acid (UOA) testing plays an indispensable role in the differential diagnosis of symptomatic individuals and the follow-up of abnormal newborn screen results. Historically, gas chromatography-mass spectrometry (GC-MS) has been the gold standard method, with well-established protocols for sample preparation and result interpretation. Recent advances in liquid chromatography-mass spectrometry (LC-MS), including both triple quadrupole and high-resolution Quadrupole Time-of-Flight (QTOF) platforms, have enabled UOA analysis with simplified workflows and improved coverage to diagnose a broader array of IEMs. This review summarizes the evolution of UOA testing from manual colorimetric assays to mass spectrometry-based platforms, highlights the analytical and interpretative considerations of GC-MS, and explores emerging LC-MS technologies and bioinformatics tools that offer enhanced diagnostic capabilities and efficiency for the future of IEM testing.