Hypercalcitoninaemia in patients with pheochromocytoma

As pheochromocytoma sometimes is accompanied by medullary thyroid carcinoma (in the sense of multiple endocrine adonomatosis type II = Sipple-Syndrome), serum calcitonin (CT) was measured by radioimmunoassay in 4 patients with pheochromocytoma. Before extirpation of the adreno-medullary tumor, serum CT was distinctly increased to 3 and 30 ng/ml in 2 of 4 patients, respectively. After removal of the tumor, serum CT was normal in the patients and pentagastrin stimulation produced no exaggerated CT response. In hydrochloric acid extracts from the two corresponding pheochromocytoma tissues, immunoreactive-Calcitonin (IR-CT) was detected, the concentrations amounting 1 and 4 ng/mg wet tissue. These findings suggest that hypercalcitonism in patients with pheochromocytoma cannot always be ascribed to the thyroid, i.e. increased calcitonin levels do not necessarily indicate a medullary carcinoma of this organ.