Amino acid ratio combinations as biomarkers for discriminating patients with pyruvate dehydrogenase complex deficiency from other inborn errors of metabolism.

Background: Pyruvate dehydrogenase complex deficiency (PDCD) is a mitochondrial neurometabolic disorder of energy deficit, with incidence of about 1 in 42,000 live births annually in the USA. The median and mean ages of diagnosis of PDCD are about 12 and 31 months, respectively. PDCD is a major cause of primary lactic acidosis with concomitant elevation in blood alanine (Ala) and proline (Pro) concentrations depending on phenotypic severity.

Hydroxocobalamin infusion in a patient monitored for plasma free hemoglobin levels.

Hemolysis is one of the most common preanalytical concerns in the clinical laboratory. Hydroxocobalamin administration causes red pigmentation of plasma that may mimic hemolysis and may interfere with chemistry assays. A male patient in his sixties was placed on extracorporeal membrane oxygenation (ECMO) as a bridge to transplantation.

Comparison of CEDIA FK506 assay with HPLC/MS/MS in a large cohort of pediatric patients.

FK506 (tacrolimus), a macrolide immunosuppressant, is widely used in pediatric transplant patients, but a relatively narrow therapeutic window in children vs adults requires close and accurate monitoring of whole blood FK506 levels. High-pressure liquid chromatography/tandem mass spectrometry (HPLC/MS/MS)-based assays have been viewed as the gold standard but are more time and labor intensive than cloned enzyme donor immunoassay (CEDIA). To analyze differences between the 2 assays, we assayed FK506 in 348 split samples simultaneously by both methods.

Variation in human erythrocyte membrane unsaturated Fatty acids: correlation with cardiovascular disease.

Context: Whether cell membrane fatty acid (FA) composition is a useful indicator of vascular disease is unclear.

Objective: To study variation of erythrocyte (RBC) membrane FA in samples from healthy volunteers, hospitalized patients, and cardiac troponin I-elevated patients with myocardial damage without a priori assumptions as to FA composition.

Design: We separated FAs extracted from RBCs by gas chromatography and identified them by mass spectrometry.