Effects of parathyroid hormone infusion and primary hyperparathyroidism on serum prolactin in man

Serum PRL, parathyroid hormone (PTH), and Ca levels were measured in 14 patients (8 women and 6 men) with primary hyperparathyroidism. Six normal volunteers (3 men and 3 women) received a 1-h control infusion of 5% glucose containing 2% human serum albumin, a 1-h infusion of the same fluid containing 450 U bovine PTH, and a repeated 1-h infusion of glucose and albumin. Serum PRL was measured during these infusion periods and showed a peak within 30 min of the start of bovine PTH infusion; PRL levels declined therafter in spite of continued PTH infusion. Serum PRL levels returned to normal within 1 h of discontinuance of bovine PTH infusion. The serum PRL levels in patients with primary hyperparathyroidism were within the normal range, and there was no correlation between serum PTH and PRL levels. These results suggest that the PRL response to PTH infusion is a pharmacological rather than a physiological or pathophysiological effect of PTH.