A Two-Site Immunoradiometric Assay for Serum Calcitonin Using Monoclonal Anti-Peptide Antibodies

We have produced a library of monoclonal antibodies of various affinities by immunizing mice with synthetic calcitonin (CT) 1-32. These monoclonal antibodies defined two antigenic determinants on the molecule of CT. The first was located in the 11-17 region of the hormone: the second was present on the 26-32 portion of CT. The C-terminal epitope was restricted to the mature form of the hormone and immunologically silent on synthetic peptides with sequences analogous lo the biosynthetic precursors for CT. Using two high-affinity monoclonal antibodies, designated as CT07 and CT08, we developed a two-site immunoradiometric assay (m-lRMA) for serum CT. This m-lRMA provided a sensitivity of 10 pg/mL using a one-step overnight incubation at room temperature. Gel filtration analyses of serum samples from patients with medullary thyroid carcinoma (MTC) demonstrated that the CT07-CT08 m-lRMA was specific for the circulating mature form of CT

Pheochromocytoma: recommendations for clinical practice from the First International Symposium. October 2005.

The First International Symposium on Pheochromocytoma, held in October 2005, included discussions about developments concerning these rare catecholamine-producing tumors. Recommendations were made during the symposium for biochemical diagnosis, localization, genetics, and treatment. Measurement of plasma or urinary fractionated metanephrines, the most accurate screening approach, was recommended as the first-line test for diagnosis; reference intervals should favor sensitivity over specificity. Localization studies should only follow reasonable clinical evidence of a tumor. Preoperative pharmacologic blockade of circulatory responses to catecholamines is mandatory. Because approximately a quarter of tumors develop secondary to germ-line mutations in any one of five genes, mutation testing should be considered; however, it is not currently cost effective to test every gene in every patient. Consideration of tumor location, presence of multiple tumors, presence of metastases, and type of catecholamine produced is useful in deciding which genes to test. Inadequate methods to distinguish malignant from benign tumors and a lack of effective treatments for malignancy are important problems requiring further resolution