Basal calcitonin levels and the response to pentagastrin stimulation in patients after kidney transplantation or on chronic hemodialysis as indicators of medullary carcinoma

Plasma concentrations of calcitonin (hCT) were determined in 150 patients w ith chronic renal failure on chronic hemodialysis therapy (CHD) and in 800 patients after successful kidney transplantation (KT). Basal hCT concentrat ions exceeded 10 pg/mL in 44 of 150 patients (29%) with CHD and in 48 of 80 0 (6%) in patients with KT. Among these patients with elevated basal hCT, p entagastrin-stimulated concentrations of hCT exceeded 100 pg/mL in 4 patien ts with CHD and in 7 with KT. Thyroidectomy was performed in 8 patients (5 with KT, 3 with CHD) revealing the presence of medullary thyroid carcinoma (MTC) (n = 2) or of C-cell hyperplasia (n = 6). Two patients with C-cell hy perplasia had the neoplastic form of this disorder. One patient with MTC an d 1 with C-cell hyperplasia also presented a papillary microcarcinoma. Stim ulated concentrations of hCT were only moderately elevated in the remaining 3 patients and follow-up rather than surgery was deemed appropriate due to their concomitant severe medical problems. In conclusion, basal concentrat ions of hCT higher than 10 pg/mL are more common in patients with CHD (29%) and after successful KT (6%) than previously described in patients with th yroid nodular disease (3%). In spite of various additional factors complica ting the interpretation of elevated hCT in CHD, pentagastrin-stimulated val ues above 100 pg/mL must be considered to indicate the presence of C-cell h yperplasia and/or of medullary thyroid carcinoma. Although thyroidectomy wo uld theoretically be the therapy of choice, the potential benefit of the op eration must be seen in the context of the patient's general condition.