Thyroid and parathyroid response to subtotal thyroidectomy.

Hypocalcemia occurring a few days after total subtotal thyroidectomy has been attributed either to parathyroid insufficiency or to calcitonin release. To investigate this matter further, we measured serum calcium, phosphate, T3, T4, TSH, parathormone (PTH), calcitonin (CT) and cAMP, in 27 women aged 23 to 63 years, before and also 3 and 7 days after subtotal thyroidectomy for multinodular nontoxic goiter. Ca, T3 and T4 decreased, whereas TSH increased appropriately to the decrease in T4 and T3. There was no increase in PTH appropriate to the Ca decrease. In contrast, PTH, cAMP and CT showed statistically unsignificant tendency to decrease. It was concluded that hypocalcemia after thyroidectomy is not due to CT release, but rather to a relative PTH insufficiency.