A Study to Compare Oral Vitamin D to Placebo for the Prevention of Low Calcium in the Blood after Surgery for the Total Removal of the Thyroid Gland.

INTERVENTION: 300 000 IU (6 capsules) of oral Vitamin D3 taken once, one week prior to surgery. CONDITION: Post‐operative Hypocalcaemia Total Thyroidectomy PRIMARY OUTCOME: The incidence of low blood calcaemia (defined as any post‐operative corrected calcium <2.10 mmol/L) SECONDARY OUTCOME: Change in parathyroid hormone blood levels from baseline. Length of inpatient hospital stay in days. The dose of calcium and calcitriol as recorded in patient medical record, and prescribed as an outpatient. The incidence of permanent hypoparathyroidsm (defined as a parathyroid blood level of <1.1 pmol/L (lower end of normal range) and requiring ongoing supplementation with 1,25(OH)D3 to maintain a corrected calcium level within the normal range The incidence of symptomatic hypocalcaemia (defined as any one of positive Chvostek’s sign, tetany, perioral paraesthesia or palpitations confirmed with ECG changes associated with any corrected calcium measurement below 2.10 mmol/L). INCLUSION CRITERIA: Patients undergoing total thyroidectomy for any cause, able to provide written informed consent. Must be able to complete follow‐up.