Intraoperative parathyroid hormone measurement in thyroidectomized patients: preliminary report

Hypocalcemia is the most frequent complication after thyroid surgery. Intraoperative measurement of parathormone levels (ioPTH) in patients undergoing thyroid surgery has been recently described as an accurate method of predicting postoperative parathyroid dysfunction. The aim of the study was to evaluate utility of ioPTH and parathormone level measured 24 hours after surgery (24PTH) as prognostic factors of hypoparathyroidism and consequent hypocalcemia.

Fifty-four patients (50 females and 4 males) underwent 55 operations: subtotal thyroidectomy (44), total thyroidectomy (8), completion thyroidectomy due to goiter reoccurrence and cancer (2 and 1 patients, respectively). PTH and serum calcium levels were assessed one day prior to surgery, intraoperatively during wound closure, on the first postoperative day and 2 months after surgery. Hypoparathyroidism was defined as parathormone level less than 15 pg/ml.

Seventeen patients presented ioPTH levels below 15 pg/ml. Twelve of them had low 24PTH levels. Only one patient with ioPTH (but not 24PTH) below 15 pg/ml developed persistent hypoparathyroidism, resulting in low parathormone level 2 months after surgery. Three investigated subjects with ioPTH greater than 15 pg/ml had low 24PTH levels but none of them developed persistent hypoparathyroidism. One patient with ioPTH and 24PTH within reference range presented hypoparathyroidism at the 2-month follow-up, presumably due to postoperative iodotherapy.

This study suggests that ioPTH and 24PTH levels are not useful prognostic factors of persistent hypoparathyroidism but may indicate transient parathyroid gland dysfunction.