The role of parathyroid ultrasonography in the management of primary hyperparathyroidism.

High-resolution, real-time sonography can be used to assess the size and location of the parathyroid glands. The authors review the types of information provided by sonography and outline the ways in which it contributes to the management of primary hyperparathyroidism. Sonography usually can differentiate parathyroid adenoma from hyperplasia. In milder cases, with less parathyroid enlargement, this differentiation is difficult but can be facilitated by determining three dimensions for each gland. Preoperative knowledge of the presumptive location of an adenoma is most useful when the strategy of unilateral neck exploration is to be used because it will allow the exploration always to begin on the correct side. Sonographic evidence of hyperplasia should trigger a preoperative search for multiple endocrine neoplasia and will alert the surgeon that a bilateral neck exploration and thymectomy will be needed. A more universal benefit is the ability to predict or exclude intrathyroidal and subcapsular parathyroid tumors, thus guiding the decision for thyroid versus thymic exploration in the event of a missing abnormal gland. Sonography often fails to visualize parathyroid tumors in an ectopic position away from the thyroid bed. Such tumors, however, may be anticipated when the sonogram shows only three enlarged glands in cases of hyperplasia, or only three glands of normal size in a patient with strong biochemical evidence of hyperparathyroidism. Because it is noninvasive and inexpensive and can provide a wealth of information, the authors have adopted sonography as a routine preoperative procedure for primary hyperparathyroidism.