One-hour PTH after thyroidectomy predicts symptomatic hypocalcemia

Abstract

Background A major morbidity following total thyroidectomy is hypocalcemia. While many clinical factors and laboratory studies have been correlated with both biochemical and symptomatic hypocalcemia, the ideal use and timing of these tests the remains unclear. We hypothesize one-hour (PACU) PTH will identify patients at risk for symptomatic hypocalcemia. Methods This prospective study evaluated 196 patients undergoing total thyroidectomy. Serum calcium and PTH levels were measured one hour after surgery and on postoperative day 1 (POD1). Performance of a central compartment lymph node dissection, parathyroid autotransplantation, indication for procedure, pathology, and presence of parathyroid tissue in the pathology specimen were recorded. Results Of 196 patients, 9 (4.6%) developed symptomatic hypocalcemia. 34 (17.3%) had a 1-hour PACU PTH ≤ 10 pg/dL while 31 (15.8%) had a POD1 PTH of ≤ 10. Five (56%) of the nine symptomatic patients underwent central compartment lymph node dissection, 4 (44%) had parathyroid autotransplantation and 4 (44%) had a PACU PTH ≤10. PACU and POD1 PTH levels were correlated (R2=0.682). Multivariate regression identified central compartment dissection, autotransplantation, and PACU or POD1 PTH correlated with symptomatic hypocalcemia. PACU PTH, POD1 PTH, PACU Ca, malignant final pathology, and Age ≤ 45 years correlated with biochemical hypocalcemia. Conclusion 1-hour postoperative PACU PTH is equivalent to POD1 PTH in predicting the development of symptomatic hypocalcemia. Biochemical hypocalcemia was not predictive of symptoms in the immediate post-operative period. Lymph node dissection and parathyroid autotransplantation correlated with symptomatic hypocalcemia and improve the sensitivity of biochemical screening alone.

Variation of Thyroidectomy-Specific Outcomes Among Hospitals and Their Association With Risk Adjustment and Hospital Performance

“…Some surgeons routinely prescribe oral supplements, whereas others favor a selective approach using postoperative levels of serum calcium, PTH, or both. 9,21,22 These data suggest that more frequently prescribing oral supplementation is associated with decreased incidence of clinically severe hypocalcemia (ie, cases resulting in clinic or emergency department evaluations or readmission). A previous study 23 found that routine calcium and vitamin D supplementation is costeffective because it decreases health care resource use, whereas another study 21 argued that selective supplementation is equally cost-effective.…”

Post-thyroidectomy Hypocalcemia - Risk Factors and Management

“…A part from prevention, treatment of hypocalcemia is indicated in patients with symptoms, with a level of corrected calcium less than 7.5 mg/dL and in acute forms when intravenous calcium is necessary (40)(41)(42). Permanent hypoparathyroidism requires lifelong followup (43,44). Recently, daily PTH injections have been introduced in one 2 years study in order to reduce the necessary of calcium and vitamin D (45).…”

Postoperative IPTH compared with IPTH gradient as predictors of post‐thyroidectomy hypocalcemia

“…The association of intraoperative or postoperative IPTH with hypocalcemia has been well described . The utility of IPTH gradient has also been explored, with optimal cut points for predicting hypocalcemia approximately 60% to 80% .…”