Publication:

An early predictor of postoperative hypocalcemia: parathyroid hormone levels 1 hour after thyroidectomy

Background The present study compares ionized calcium (Ca2+) levels with preoperative serum PTH and with those obtained at 1, 6 and 24 hours after total thyroidectomy with an emphasis on the 1-hour PTH (PTH-1) and the subsequent development of hypocalcemia.

Methods This is a retrospective study which consisted the cases of consecutive patients undergoing total or completion thyroidectomy between August 2010 and January 2012.

Results In this study, 200 patients were studied, out of which 24 (12%) were males and 176 (88) were females. The median age of patients in the entire cohort was 60 years. 151 (75.5%) patients underwent total thyroidectomy and 49 (24.5%) patients underwent complete thyroidectomy for malignancy of the entire cohort. 160 (80%) patients had been diagnosed of primary thyroid cancer. 40 (20%) were diagnosed of benign cancer. The mean PTH levels showed significantly higher at 24 hours postoperative in eucalcemic patients, but decreased by PTH-24. The r coefficients were compared between PTH-1, PTH-6 and PTH-24 were 0.85 and 0.99 thus reflecting the relative stability of PTH measurements within first 24 hours postoperative. Hypocalcemia (normal range-1.1-1.32 mmol/L) was 8 (4%) at 1 hour, 20 (10%) at 6 hour and 96 (48.2%) at 24 hour respectively. Factor PTH-1 >1.5 pmol/L, the Ca+2 1.1 mmol/L were 124, for factor PTH-1≤ 1.5 pmol/L, the Ca+2 1.1 mmol/L were 0.

Conclusions Those who are at risk of hypocalcemia 24 hours postoperatively, our results suggest that PTH-1 is an excellent predictor. To avoid hypocalcemia, therapy with calcitriol should be started if PTH-1 is less than 1.5 pmol/L.