Post-Thyroidectomy Hypocalcemia: Incidence, Prediction, and Outpatient Management Strategies Based on PTH and Calcium Levels

Abstract

PTH measurement has been proposed to predict transient and permanent postoperative hypocalcemia. There is no standard cut-off point or time for sampling. To report the incidence of post-thyroidectomy hypocalcemia in a high-volume surgical group and propose an outpatient management protocol according to postoperative (PO) calcium levels, iPTH (normal, low, or undetectable), and symptoms. Furthermore, determine postoperative PTH values as predictors of hypocalcemia. In 106 patients with total thyroidectomy between 2019 and 2021, pre-and postoperative levels of calcium, magnesium, phosphorus, and iPTH were measured. Transient (< 12 months) and permanent (> 12 months) hypocalcemia was observed in 29% and 1%. Cut-off points to predict hypocalcemia were PTH < 8.8 pg/mL and < 80% decrease in % PTH (d% PTH) the day after surgery. With the proposed management, early discharge is indicated (an average of 1.05 days), and the prescription cost is limited. There is no significant association between PO hypomagnesemia and hyperphosphatemia with PO hypocalcemia. The most widely used treatment is exclusive calcium carbonate (schemes I and II). Patients remain with mild symptoms at two weeks PO in 5% and discontinue oral treatment in 93% in this period. Protocols for measuring PTH as a hypocalcemia predictor vary. Each center must know and establish its management protocols. With this experience, we demonstrate the usefulness and safety of a management scheme based on calcium, PTH (normal, low, or undetectable), and symptoms with an indication of prophylactic treatment for all patients and a safe outpatient setting at a lower cost than prolonged hospitalization.