Can postoperative calcemia kinetics predict the risk of hypocalcemia for the management of parathyroid adenoma in ambulatory surgery?

INTRODUCTION: The goal of this study was to analyse the kinetics of corrected calcemia levels (Cac) after parathyroid excision and to determine the percentage of variation (ΔCa) in the initial hours after surgery, in order to entertain an early discharge. POPULATION AND METHODS: Were included in this study, patients undergoing operation for parathyroid adenoma responsible for primary hyperparathyroidism (PHP). The Cac was measure preoperatively and four hours after surgery, and then every day until patient discharge. Group A included patients for whom the Cac was inferior to 2.2mmol/L at least once postoperatively while group B included patients for whom the Cac was always equal or superior to 2.2mmol/L. The ΔCa represented the percentage of the fall in postoperative Cac with respect to preoperative Cac. RESULTS: Between 2010 and 2017, 156 patients fulfilled the inclusion criteria (women 80.8%, [sex ratio 1:4], median age 64 years old). Preoperative Cac was statistically significantly lower in group A compared to group B (2.67 vs. 2.82mmol/L; P<0.0001). In total, 9.6% of patients had calcium supplementation for hypocalcemia, symptomatic or not. Postoperative Cac reached its nadir value on postoperative day 2. At four hours postoperative, the risk of postoperative calcelmia falling below 2.2mmol/L appeared when the ΔCa was superior to 6% with a sensitivity of 92.9% and a negative predictive value of 97.4%. CONCLUSION: After excision of a parathyroid adenoma for PHP, the Cac falls rapidly and reaches its nadir value on day 2. If the fall in calcemia is less than 6% four hours after surgery (vs. preoperative level), early discharge within the framework of ambulatory surgery is possible.