Background: Hypocalcemia after total thyroidectomy is a frequent complication that can be predicted and best managed by the postoperative measurement of parathyroid hormone levels.
Methods: This study included consecutive patients who underwent total thyroidectomy between 2017 and 2022. Hypocalcemia was defined as serum calcium <8.0 mg/dL and hypoparathyroidism as parathyroid hormone <15 pg/mL. After comparing serum calcium levels on postoperative day 1 and intraoperative parathyroid hormone levels 20 minutes after total thyroidectomy in the first period, an algorithm involving routine postoperative oral calcium and alfacalcidol administration in patients with intraoperative parathyroid hormone levels 20 minutes after total thyroidectomy <20 pg/mL was developed and tested during the second period. The rates of symptomatic hypocalcemia, readmission for hypocalcemia, and permanent hypoparathyroidism were compared between the 2 periods.
Results: In the first period, 1,965 total thyroidectomies (1,548 women; mean age, 51 years) were performed, including 617 patients (31%) with central neck dissection for thyroid carcinoma. Of 314 patients (16%) who experienced symptomatic hypocalcemia, only 183 (58%) could be predicted using serum calcium levels on postoperative day 1 <8.0 mg/dL. This rate increased to 96% (301 patients) when using intraoperative parathyroid hormone levels 20 minutes after total thyroidectomy and serum calcium levels on postoperative day 1 (P < .001). Intraoperative parathyroid hormone levels 20 minutes after total thyroidectomy alone could predict symptomatic hypocalcemia in 90% (282) of patients. Hypoparathyroidism was permanent in 20 patients (1%), with a greater predictive value of intraoperative parathyroid hormone levels 20 minutes after total thyroidectomy over serum calcium levels on postoperative day 1 (18/20 [90%] vs 8/20 [40%], P < .01). Using the intraoperative parathyroid hormone levels 20 minutes after total thyroidectomy-based algorithm and preventive calcium supplementation in the second period of the study, 1,420 total thyroidectomies (1,106 women; mean age, 50 years) were performed, including 392 (28%) cases with central neck dissection for thyroid carcinoma. Only 2.3% (32) patients developed a symptomatic hypocalcemia compared with 16% during the first period (P < .001). Thirty-eight patients (2.7%) experienced readmission after total thyroidectomy before implementation of the supplementation protocol in our study compared with 2 patients (0.01%) after we began using the protocol (P < .001). There was no significant difference in permanent hypoparathyroidism between the 2 periods (1.3% vs 1%) (P = .8).
Conclusions: The parathyroid hormone-based algorithm determined by intraoperative parathyroid hormone levels 20 minutes after total thyroidectomy and routine preventive administration of oral calcium/calcitriol reduced the risk of symptomatic hypocalcemia and readmission after total thyroidectomy.
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