Abstract
IntroductionHypocalcemia is one of the most common complications after total thyroidectomy. Preoperative serum vitamin D concentration has been postulated as a risk factor for this complication. However, the subject is still controversial and the role of vitamin D in the occurrence of hypocalcemia remains uncertain. ObjectiveTo evaluate the capability of preoperative vitamin D concentrations in predicting post-total thyroidectomy hypocalcemia. MethodsForty-seven total thyroidectomy patients were prospectively evaluated for serum 25(OH) vitamin D, calcium and parathyroid hormone before surgery, Calcium every 6 hours, and parathyroid hormone 8 hours post-operatively. Patients were divided according to postoperative corrected calcium into groups without (corrected calcium ≥8.5 mg/dL) and with hypocalcemia (corrected calcium <8.5 mg/dL), who were then evaluated for preoperative 25(OH) vitamin D values. ResultsA total of 72.3% of cases presented altered 25(OH) vitamin D preoperative serum concentrations and 51% evolved with postoperative hypocalcemia. The with and without hypocalcemia groups did not differ for preoperative 25(OH) vitamin D (p = 0.62). Univariate analysis showed that age (p = 0.03), postoperative PTH concentration (p = 0.02), and anatomopathological diagnosis of malignancy (p = 0.002) were predictors of postoperative hypocalcemia. In multivariate analysis only parathyroid hormone in postoperative (p = 0.02) was associated with post-total thyroidectomy hypocalcemia. ConclusionPreoperative serum concentrations of 25(OH) vitamin D were not predictors for post-total thyroidectomy hypocalcemia, whereas postoperative parathyroid hormone influenced the occurrence of this complication.
Highlights
Hypocalcemia is one of the most common complications after total thyroidectomy
In this study, evaluating a group of relatively homogenous patients submitted to total thyroidectomy, we observed that preoperative serum 25(OH) Vitamin D (25OHD) concentrations were not predictors of post-surgery hypocalcemia
Vitamin D deficiency with a consequent reduction in intestinal calcium absorption leads to the compensatory secondary hyperparathyroidism with hypertrophy of the parathyroid glands and increased bone and renal calcium reabsorption induced by Parathyroid Hormone (PTH)
Summary
Hypocalcemia is one of the most common complications after total thyroidectomy. Preoperative serum vitamin D concentration has been postulated as a risk factor for this complication. Despite the most frequent etiology of post-total thyroidectomy hypocalcemia being hypoparathyroidism, secondary to intraoperative direct removal or devascularization of the parathyroid,[3] other factors seem to predispose to this clinical-laboratory condition, such as hemodilution, calcitonin liberation, advanced age, Graves’ disease, surgical technique, and surgeon experience.[4,5] Recently some authors have suggested that serum vitamin D concentrations could present a risk factor for hypocalcemia development.2,4,6---8. Falcone et al retrospectively evaluating 264 patients, concluded that 25OHD did not predict a drop in post-operative calcium.[3] Lang et al reported that preoperative 25OHD deficit (values below 20 ng/mL) did not increase the post-thyroidectomy hypocalcemia rate.[10] Some of the reasons for these discordant results could be the criteria used to diagnose hypocalcemia, cut points for 25OHD, and study group heterogeneity
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