Laboratory Indicators for Predicting Hypocalcemia After Total Thyroidectomy. A Study from A Tertiary Hospital in Saudi Arabia

Background: Hypocalcemia is a common complication after total thyroidectomy and it is the most important factor for discharging a patient who underwent total thyroidectomy. Therefore, tools are needed to identify the risk of hypocalcemia in patients who are undergoing total thyroidectomy. Aim: The present study aimed to examine various preoperative parameters for predicting hypocalcemia. Patients and Methods: A prospective study evaluated consecutive patients who had fulfilled the surgical indications for total thyroidectomy, at two Saudi tertiary hospitals during 2017–2018. Standardized preoperative assessment that includes routine laboratory testing and measuring the corrected serum levels of calcium, vitamin D, phosphorus, and magnesium. At 6 hour after the surgery, all laboratory parameters were re-tested. The different variables were tested using Pearson's correlation analysis, the related-samples T-test, the independent-samples T-test, and repeated measures analysis of variance. Results: Total of 90 patients who underwent total thyroidectomy. The mean age of 41 ± 12 years, and included 20 men (22.2%) and 70 women (77.8%). The preoperative labs parameters (e.g., phosphorus, magnesium, albumin, vitamin D, and PTH) had poor predictive values for differentiating between the patients with and without hypocalcemia.The only significant difference was observed for postoperative PTH (p=0.037), and the postoperative magnesium and phosphorus levels were not statistically significant (p=0.200 and p=0.997, respectively). Conclusion: Our study showed that postoperative PTH levels reliably predicted postoperative hypocalcemia. We also found that hypocalcemia was not reliably predicted by age, sex disease type, or the preoperative and postoperative values for vitamin D, phosphorus, and magnesium.