Procalcitonin: a marker for the diagnosis and follow-up of patients with medullary thyroid carcinoma.

Context: 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.

Plasma chromogranin A or urine fractionated metanephrines follow-up testing improves the diagnostic accuracy of plasma fractionated metanephrines for pheochromocytoma.

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.

A two-center international evaluation of the Immulite 2000 automated serum gastrin assay.

Objectives: To assess the performance of the Immulite 2000 serum gastrin assay.

Design And Methods: Two-center validation and comparison with two manual gastrin assays.

Results: Serum, serum separator, EDTA and heparin tube results differed <20%.

Phantoms in the assay tube: heterophile antibody interferences in serum thyroglobulin assays.

Serum thyroglobulin (Tg) measurement is a major means of detecting thyroid cancer recurrence. Unlike anti-Tg autoantibody interferences, heterophile antibody (HAB) immunoassay interferences are not well recognized by laboratorians or clinicians as a Tg assay problem. When HAB interferences occur, they usually result in false positive test results.