Preoperative Vitamin D Deficiency as a Predictor of Post-total-thyroidectomy Hypocalcemia

Abstract

Objectives:

Understand the relationship between preoperative vitamin D deficiency and post-total-thyroidectomy hypocalcemia.

Methods:

Retrospective study examining 264 total and completion thyroidectomies between 2007-2011. Included patients had a recorded 25OH-D level within 21 days prior to or 1 day following surgery, were not taking ergocalciferol (D2) at the time of their lab draw, did not have a primary parathyroid gland disorder, and were not taking calcitriol (1,25 dihydroxy-D3) prior to surgery. Some patients were repleted preoperatively if a low 25OH-D level was identified. Preoperative 25OH-D, concurrent neck dissection, integrity of parathyroid glands, final pathology, postoperative parathyroid hormone (PTH), calcium nadir and repletion, and length of stay were examined.

Results:

In this cohort, a mean of 3 parathyroid glands were identified during surgery. Multinodular goiter and papillary thyroid carcinoma were the most common pathologies. Hypocalcemia, defined as a corrected calcium <8.4 mg/dL, and drain placement were the most common reasons for length of stay >1 night. The average preoperative 25OH-D for all patients was 24.98 ng/mL and the overall rate of hypocalcemia was 37.5%. Low preoperative 25OH-D did not predict postoperative hypocalcemia (P = 0.96), however, it did predict the need for postoperative calcitriol administration (p=0.01). Lower postoperative PTH levels (P = 0.001) predicted postoperative hypocalcemia.

Conclusions.

Lower postoperative PTH predicts post total thyroidectomy hypocalcemia. Preoperative 25OH-D did not predict hypocalcemia as has been previously described although it did predict the use of calcitriol postoperatively. We recommend that 25OH-D be assessed and, if indicated, repleted preoperatively in patients undergoing total thyroidectomy.