THALLIUM-TECHNETIUM SUBTRACTION SCINTIGRAPHY OF ENLARGED PARATHYROID-GLANDS AFTER CALCITONIN STIMULATION OF PARATHYROID-HORMONE SECRETION

To improve the sensitivity of thallium-technetium subtraction scintigraphy for preoperative localization procedure of enlarged parathyroid glands in primary hyperparathyroidism, we administered 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/l to 1.41+/-0.09 mmol/l (p<0.01). Concomitantly, serum levels of intact parathyroid hormone increased from 6.4+/-2.5 pmol/l to 7.9+/-2.6 pmol/l (p<0.001). The scintigram after calcitonin injection visualized 11 adenomas (sensitivity 78%) compared to only 9 (sensitivity 64%) in conventional 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 calcitonin injection improved the scintigram in 7 cases and was inferior in only one case (p = 0.03 1). We conclude that stimulation of parathyroid hormone secretion with calcitonin results in a better preoperative localization of enlarged parathyroid glands in primary hy perparathyroidism.