An Algorithm Informed by the Parathyroid Hormone Level Reduces Hypocalcemic Complications of Thyroidectomy

BACKGROUND: Measurement of the parathyroid hormone (PTH) level following total thyroidectomy (TTx) may allow prediction of postoperative hypocalcemia. We present an algorithmic method of managing hypocalcemia pre-emptively, based on the PTH level 1 h after operation. MATERIALS AND METHODS: We examined 423 consecutive patients undergoing TTx at a single institution. A subset of patients were managed using an algorithm involving routine postoperative oral calcium administration and the early addition of oral calcitriol in patients with a low 1-h postoperative PTH level. Algorithm patients were compared to a concurrent, conventionally managed group. Outcomes measured included serum calcium levels, symptoms of hypocalcemia, postoperative complications, and receipt of intravenous (IV) calcium. RESULTS: The algorithm was applied in 135 patients, and 288 patients were managed conventionally. Critically low calcium levels (total calcium <7.5 mg/dl [1.88 mmol/l] or ionized calcium <0.94 mmol/l) were less common in algorithm patients (10.6% vs. 25.3%; p < 0.005). Much of this difference was attributable to the protective impact of the algorithm on patients undergoing TTx for cancer, 30% of whom developed critically low calcium levels when managed conventionally. Among patients requiring IV calcium, algorithm patients received fewer doses (1.29 vs. 1.86; p < 0.05). Low 1-h PTH levels were found in 21% (28/133) of algorithm patients, but these did not correlate with low calcium levels, suggesting that the algorithm compensated adequately for temporary hypoparathyroidism. No patients developed hypercalcemia. CONCLUSIONS: An algorithmic approach incorporating early postoperative PTH levels and routine administration of oral calcium reduces the risk of severe hypocalcemia after total thyroidectomy.