Endocrine Abstracts

Hypocalcemia is a classic complication after total thyroidectomy, mostly due to post-operative hypoparathyroidism. However others factors, like vitamin D deficiency, may contribute to this hypocalcemia.

Objective: To determine if vitamin D preoperative status influence early postoperative serum calcium levels after total thyroidectomy.

Patients and methods: Seventy-nine patients (65 women/14 men), mean age 52.8 (±12.7), were included. Patients were distributed in 3 groups according to their early postoperative serum calcium levels: – severe hypocalcemia ≤1.8 mmol/l (1.72 (1.48–1.8)), – mild hypocalcemia 1.8 to 2.1 mmol/l (1.95 (1.83–2.08)), – normocalcemia ≥2.1 mmol/l (2.13 (2.1–2.21)).

Results: Severe vitamin D deficiency (≤10 ng/ml) is present only in the mild hypocalcemia group (0 vs 20.9 vs 0%, P=0.01).There is a trend for lower levels in the mild hypocalcemia group (21.9 (11.1–87) vs 16.5 (0–71) vs 24 (12.9–47.5), P=0.057). FT₄ is significantly lower in patients with hypocalcemia (severe and mild) (1.15 ng/dl (0.52 and 1.67) vs 1.26 ng/dl (1.05 and 1.96), P=0.02). In univariate logistic regression analysis, 25OHD and FT₄ levels are predictive factors of early postoperative hypocalcemia (1.006 (1.003–1.009), P<0.0001 and 1.01 (1.005–1.015), P<0.0001 respectively). In multivariate analysis, only 25OHD remain with a statistical trend (P=0.06).

Conclusion: Severe hypocalcemia is due to hypoparathyroidism but vitamin D deficiency participate to mild hypocalcemia. Screening and treatment of vitamin D deficiency as well as obtaining FT₄ normal levels before surgery could avoid some hypocalcemia after total thyroidectomy.