Background: Total thyroidectomy is the most common surgical treatment of thyroid diseases, and postoperative hypocalcemia is its most common complication. Hypocalcemia prolongs the patient's hospital stay and impairs his or her quality of life. Although a low vitamin D level is a recognized risk factor, the utility of preoperative vitamin D administration to prevent postoperative hypocalcemia is unclear. In this trial, therefore, we studied the effect of giving vitamin D before total thyroidectomy.
Methods: In a multicenter, randomized, minimally interventional trial (registration number: DRKS 00005615), patients about to undergo total thyroidectomy were randomized either to an intervention group that received 0.5 μg of calcitriol per os twice daily for three days up to the day immediately before surgery, or to a control group that did not (no placebo was given). The primary endpoint was the absence of hypocalcemia (serum calcium <2.1 mmol/L) in the postoperative course.
Results: Of the 287 patients recruited in six hospitals over the period 23 July 2014 to 20 March 2017, 246 were included in the final analysis. The intervention and control groups did not differ significantly with respect to the rate of postoperative hypocalcemia (29.2% and 33.6%, respectively; p = 0.546, power 8.8%). The duration of postoperative hypocalcemia was, however, shorter in the intervention group (3.5 vs. 7 days; p = 0.016, power 68%). The rates of hypocalcemia in the individual trial locations varied widely, ranging from 13.9% to 71.4%.
Conclusion: Short-term administration of calcitriol did not affect the rate of occurrence of hypocalcemia after thyroidectomy, but did shorten its duration. The rate of postoperative hypocalcemia varied widely across hospitals, probably because of differences in surgical technique.