Are biochemical values predictive of adenoma's weight in primary hyperparathyroidism?

Preoperative laboratory findings may carry some predictive value about the size of the abnormal parathyroid tissue that needs to be removed in primary hyperparathyroidism.

In a retrospective study from 1988 to 2003, records of 71 patients with parathyroid adenoma were reviewed. The correlation between preoperative serum calcium, phosphate and parathyroid hormone (PTH) with adenoma's weight was analysed separately.

There was a significant correlation between preoperative serum PTH and calcium with adenoma's weight (P < 0.001 and P = 0.03, respectively). The correlation between preoperative serum phosphate and adenoma's weight was not significant (P = 0.1).

Preoperative PTH level cannot be used as a definite guide to the parathyroid adenoma's weight. Large parathyroid adenomas seem to secrete less PTH per unit weight than small adenomas. Calcium and phosphate do not seem to be of much value in predicting adenoma's weight in primary hyperparathyroidism.