Routine calcium measurement is not necessary after most thyroid surgeries: a prospective clinical study

Calcium levels are often measured to diagnose postoperative hypocalcaemia following thyroidectomy. The aims of this study were to (i) prospectively determine the incidence of symptomatic and biochemical hypocalcaemia following thyroidectomy, (ii) to identify if any associations exist between hypocalcaemia, type of surgery, histological diagnosis, specimen size/weight and the presence of histological parathyroid tissue and (iii) to evaluate the necessity of routine measurement of calcium levels following all thyroidectomies.

Prospective clinical study.

University teaching hospital.

Eighty-six patients presenting consecutively for thyroid surgery.

Type of surgery, indications, perioperative calcium levels, symptoms of hypocalcaemia and histology were documented.

Fifty-four patients underwent thyroid lobectomy and isthmusectomy, 19 underwent total and 13 completion thyroidectomy. Significantly, no patient undergoing thyroid lobectomy developed hypocalcaemia versus 26% of total thyroidectomies (P=0.001) and 23% of completion thyroidectomies (P=0.006). All eight patients with hypocalcaemia required treatment. Seven were initially identified clinically. Logistic regression analysis revealed that operation type was the only independent risk factor for developing hypocalcaemia (P=0.021).

No patient developed hypocalcaemia following thyroid lobectomy and isthmusectomy. Considering the majority (63%) of thyroid surgeries were lobectomies, most patients tested appear low risk for hypocalcaemia. Definitive prediction of hypocalcaemia postoperatively remains a challenge. However, our results suggest that analysing calcium levels routinely following thyroid lobectomy is unwarranted.