Failure to Increase Parathyroid Hormone Predicts Hypocalcemia After Neck Surgery for Endocrine Diseases: A Referral Center Experience With High Risk Patients

Abstract

Introduction Transitory hypoparathyroidism occurs in 16.5-71% of patients undergoing total thyroidectomy. Parathyroid hormone (PTH) rises quickly after serum calcium concentrations drop, before true hypocalcaemia ensues. We aimed to determine if this behavior is different in patients with or without hypocalcaemia after neck-surgery for endocrine diseases. Methods Total serum corrected calcium and intact PTH were determined before surgery and 6h after, calcium determined at 12h, 28h and 24h after surgery too, and compared between groups. Patients with other acute or chronic comorbidities that affect calcium metabolism were not included. Results 83 patients, 86.7% women (47% premenopausal), with a median age of 52 years were evaluated. In total, 59% had biochemical hypocalcemia, while only 28.9% were symptomatic. A decrease of iPTH of greater than 9.5pg/mL in the first 6 hours had a sensitivity of 100% and a specificity of 92.5% to predict hypocalcemia. Discussion: most patients had a decrease in calcium during the first hours after surgery, but the patients without hypocalcemia had an appropriate increase of iPTH, while the patients that developed hypocalcemia had the opposite response. Conclusion: inappropriate reductions of iPTH in the first few hours after neck surgery for endocrine diseases, may be associated with hypocalcemia during the early postoperatory days. Clinical characteristics may be insufficient to detect the patients that will benefit from prophylactic calcium supplementation in some cases.