S139 – Intact Parathyroid Hormone as a Predictor of Hypocalcaemia

Objectives 1) To investigate intact Parathyroid Hormone (ipth) as a predictor of hypocalcaemia in post‐total thyroidectomy patients. 2) To determine the sensitivity and specificity of ipth as a predictor of hypocalcaemia. Methods Prospective study involving 65 patients in a single institution accrued over 2 years. All patients scheduled for total thyroidectomy were empirically started on calcium and vitamin D replacement on the day of surgery. Intact Parathyroid Hormone (ipth) levels were taken 4–6 hours after completion of operation. Corrected calcium levels were also obtained 4–6 hours after completion of operation and 24 hours later. All patients were subsequently monitored for development of hypocalcaemia. Hypocalcaemia is defined as corrected serum calcium of < 1.9 mmol/L or clinical symptoms of cramps or peri‐oral numbness. Results 18 of 65 patients developed hypocalcaemia. All patients who developed hypocalcaemia had a ipth level of < 0.6 pmol/L. Using 0.6 as a cut‐off value, ipth has a sensitivity of 100% and specificity of 76% in our study. Conclusions Using a cut‐off value of 0.6pmmol/L, early postoperative intact parathyroid hormone has a high sensitivity and good specificity in identifying patients who subsequently develop hypocalcaemia post‐total or completion thyroidectomy and can be used identify patients who need close calcium monitoring in the postoperative period.