[Symptomatic hypocalcemia after thyroidectomy : Prevention by a combination of prophylaxis and risk-adapted substitution]

Abstract

Background: Treatment of hypocalcemia after thyroidectomy consists of an individual substitution, prophylaxis or a daily administration of calcium/vitamin D3.

Objective: Does prophylactic therapy combined with a risk-adapted substitution of calcium and vitamin D3 reduce symptomatic hypocalcemia compared to individual substitution?

Material and methods: After implementation of a new algorithm, patient data were prospectively documented and analyzed compared to a historical patient population. The algorithm consisted of a single prophylactic i. v. administration of calcium (1 g calcium gluconate 10% in 250 ml saline) and a risk-adapted oral administration of calcium and vitamin D3 after surgery. Patients without risk (parathyroid hormone, PTH > 15 pg/ml) were not treated. Patients with a low risk (PTH ≥ 6 ≤ 15 pg/ml and Ca > 2.0 mmol/l) received 3 g calcium, patients with a high risk (PTH ≥ 6 ≤ 15 pg/ml and Ca < 2.0 mmol/l) received 3 g calcium and 2 × 0.5 µg vitamin D3 and patients with a very high risk (PTH < 6 pg/ml) got 4 g calcium and 2 × 0.5 µg vitamin D3.

Results: In this study 415 patients were included (230 prospectively and 185 retrospectively). Serum calcium of patients with individual substitution increased significantly at day 1 (p = 0.0001) and the number of patients with critical hypocalcemia (Ca < 2.0 mmol/l) decreased by half (27% vs. 12.2%; p = 0.0001). There was a significantly lower rate of symptomatic patients (24.9% vs 13.0%; p = 0.002) and a clear reduction of patients with a prolonged hospitalization (10.8% vs. 6.5%; p = 0.08). The rate of permanent hypocalcemia was comparable (2.2% vs. 2.1%). In the risk groups there was a significantly different rate of hypocalcemia: patients without risk (n = 170) in 2.2%, patients with low risk (n = 36) in 25%, patients with high risk (n = 13) in 69.2% and patients with very high risk (n = 11) in 71%.

Conclusion: This new treatment regimen is practicable, significantly lowers the symptoms, also in comparison to the literature and shows a clear differentiation between the risk groups.

Keywords: Hypocalcemia; Hypoparathyroidism; Tetany; Thyroidectomy; Vitamin D3.