Introduction: The purpose of this study was to analyse the relationship between preoperative serum levels of vitamin D and postoperative hypocalcaemia after total thyroidectomy. Material and methods: A prospective observational study was conducted on 113 patients treated by total thyroidectomy due to benign disease. Preoperative vitamin D serum levels and postoperative albumin-corrected calcium and parathormone (PTH) levels were determined. Sensitivity, specificity, positive predictive value and negative predictive value of vitamin D and PTH levels, respectively, in the diagnosis of postoperative hypocalcaemia were calculated. Results: Hypocalcaemia was diagnosed in 44 (38.9percent-flag-change) patients. Vitamin D levels were significantly higher in the group of patients with normal postoperative calcium (median: 25.4. pg/mL; range: 4-60), compared to those who developed hypocalcaemia (median: 16.4. pg/mL; range: 6.3-46.9) (P=.001). Postoperative hypocalcaemia was more frequent in patients with vitamin D ylt; 30. ng/mL (39/78) (50percent-flag-change), than among those with normal levels (5/35) (14.2percent-flag-change) (P=.001). Sensitivity, specificity, positive predictive value and negative predictive value were 88percent-flag-change and 68percent-flag-change, 43percent-flag-change and 82percent-flag-change, 50percent-flag-change and 71percent-flag-change, and 85percent-flag-change and 80percent-flag-change for vitamin D and PTH, respectively. Vitamin D and PTH showed independent prognostic values on the risk of hypocalcaemia. The OR associated with vitamin D ylt; 30. ng/mL was 4.25 (95percent-flag-change CI: 1.31-13.78) (P=.016), and the OR of PTHylt;13 pg/mL was 15.4 (95percent-flag-change CI: 4.83-49.1) (Pylt;.001). Conclusion: Vitamin D deficiency is a risk factor of hypocalcaemia after total thyroidectomy for benign goitre. The vitamin D level provides independent prognostic information, which is complementary to that given by PTH.
