Thallium/technetium subtraction scanning for primary hyperparathyroidism: scan sensitivity and effect on operative time.

Over a ten-year period 26 patients were evaluated by the authors for elevated serum calcium and parathormone levels. All patients were clinically asymptomatic and were referred for parathyroid evaluation following a diagnosis of hypercalcemia made on routine SMA-12 studies. Twenty-four patients had positive thallium/technetium subtraction studies; two were suggestive of bilateral adenomata, one of which was confirmed at surgery. In two patients both thallium/technetium and technetium sestamibi scanning studies were negative. These patients were managed medically without surgical exploration. In all operative cases the patients remained normocalcemic during a six-month follow-up period. Operative times in all cases were less than one hour.