Introduction:
Hypocalcaemia remains the most common postoperative complication after total thyroidectomy. The purpose of the study was to evaluate the clinical usefulness of routine preoperative oral calcium and vitamin D supplementation in the prevention of hypocalcaemia after total thyroidectomy.

Material and methods:
One hundred fifty-three consecutive patients with nontoxic multinodular goitre were randomly assigned to routinely receive (group B) or not to receive (group A) calcium carbonate (3 g/d) and alfacalcidol (1 µg/d) on the day before surgery and calcium carbonate (1 g/d) and alfacalcidol (1 µg/d) taken once in the morning on the day of operation. Their preoperative 25-hydroxyvitamin D (25-OHD) levels, hypocalcemic symptoms, serum calcium and parathyroid hormone (iPTH) levels were determined 6 and 24 hour postoperatively and 6 weeks after surgery.

Results:
Symptomatic hypocalcaemia was observed in 41/153(26.79%) patients. The incidence of symptomatic hypocalcaemia was significantly lower in the supplemented group than in the group not receiving supplementation: 10 of 77 participants (12.99%) versus 31 of 76 patients (40.79%) (p<0.05). The rates of laboratory and severe hypocalcaemia (corrected calcium <2.0 mmol/l) were 67.11% and 28.95% in group A and 50.65% and 9.09% in group B, respectively (p=0.04, p<0.05). There were no significant differences between groups A and B in corrected calcium levels after surgery and postoperative decreases in corrected calcium levels (p=0.06). 112(73.20%) participants had 25-OHD<20 ng/ml. Vitamin D levels did not influence corrected calcium level changes (p=0.98).

Conclusions:
Oral supplementation of calcium and alfacalcidol may help in the prevention of postthyroidectomy hypocalcaemia. Vitamin D deficiency was widespread among operated patients.