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

Background: The present study compares ionized calcium (Ca 2+ ) 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.