Thallium-Technetium Subtraction Scintigraphy of Enlarged Parathyroid Glands after Calcitonin Stimulation of Parathyroid Hormone Secretion

Abstract

To improve the sensitivity of thallium-technetium subtraction scintigraphy for preoperative localization procedure of enlarged parathyroid glands in primary hyperparathyroidism, we adminis tered calcitonin intramuscularly 4 hours before the scintigraphy in 14 consecutive patients. Injection of calcitonin reduced plasma levels of ionized calcium from 1.47 + 0.10 mmol/1 to 1.41+0.09 mmol/1 (p<0.01). Concomitantly, serum levels of intact parathyroid hor mone increased from 6.4 + 2.5 pmol/1 to 7.9±2.6 pmol/1 (p<0.001). The scintigram after calcitonin injection visualized 11 adenomas (sensitivity 78%) compared to only 9 (sensitivity 64%) in convention al scintigrams. In addition, 5 of the adenomas were more distinctly imaged in the scintigram after calcitonin injection, whereas in only one patient was the conventional scintigram better. Thus, the calci tonin injection improved the scintigram in 7 cases and was inferior in only one case (p = 0.031). We conclude that stimulation of para thyroid hormone secretion with calcitonin results in a better preop erative localization of enlarged parathyroid glands in primary hy perparathyroidism.