Failure of cyproheptadine to affect homoeostasis and PTH levels in primary hyperparathyroidism

Cyproheptadine was given in a dose of 4 mg orally every 4 hours during 10 consecutive days to six patients with primary hyperparathyroidism. Control fasting blood samples for PTH, Ca, Mg and P were obtained every other day for a week. Afterwards cyproheptadine treatment was applied as mentioned above. Then blood samples were taken on the 4th, 6th, and 10th day of treatment to determine serum PTH, Ca, Mg and P. Before treatment the mean PTH ( plus or minus SE) values were 22.95 plus or minus 1.4 mlU/ml and during cyproheptadine treatment were 23.06 plus or minus 0.9, 22.95 plus or minus 0.8, 22.32 plus or minus 0.8 mlU/ml, respectively. There were no significant changes in serum PTH levels before and during treatment. Also serum Ca, Mg and P levels remained unchanged. The data suggest that cyproheptadine treatment does not affect calcium homoeostasis and serum PTH levels in primary hyperparathyroidism.