[Localization diagnosis of enlarged parathyroid glands: 201Tl-99mTc-subtraction scintigraphy compared with 5-MHz-sonography].

Fifty patients clinically suspected of having primary hyperparathyroidism were examined by scintigraphy (201Tl-99mTc subtraction) and sonography (5 MHz). In 28 cases, the results of subtraction scintigraphy, and in 26 cases, the results of sonography were checked by operation. In 25 patients there was a solitary parathyroid adenoma and in two, primary hyperplasia. In one patient all four parathyroid glands were normal. Subtraction scintigraphy had a sensitivity of 90% and a specificity of 98%, while sonography had a sensitivity of 82% and a specificity of 95%. The combination of 201Tl-99mTc subtraction scintigraphy as a functional investigation and sonography as a structural imaging method produced a sensitivity of 96% and is therefore superior to all other methods of localisation for normally situated glands. Diagnostic certainty is reduced by the presence of a nodular thyroid.