[IPTH dosage as a prognosis predictor of postoperatory hypocalcemia in patients submitted to total thyroidectomy]

Hypocalcemia is the most frequent complication after total thyroidectomy (TT) and represents the main cause of prolonged hospital stay because of the need to monitor the calcemic status of the patients. The aim of this study is to evaluate the role of serum iPTH as a predictor of post-thyroidectomy hypocalcemia in order to allow patients' early and safe discharge.

Fifty patients who underwent TT without autotransplantation of parathyroid tissue were prospectively included in the study The mean age was 52 years and the male/female ratio was 1/6. The iPTH serum level were determined 1 hour after the operation and the calcium serum values after 24 and 48 hours. The cut-off value assumed for testing the sensitivity, specificity, PPV and NPV was 16 pg/ml.

Nineteen patients (38%) presented hypocalcemia within 48 hours after TT and 16 of them (84.2%) had iPTH serum levels lower than 16 pg/ml. The normocalcemic patients were 31 (62%) and only 4 of them had iPTH serum levels inferior to the cut-off value. Postoperative iPTH serum level determined 1 hour after the operation had a sensibility of 84.2%, specificity of 87.1%, PPV and NPV of 90% and 80% respectively.

The dosage of iPTH serum levels after total thyroidectomy reliably predicts patients who are likely to develop hypocalcaemia. It may be useful in clinical practice in order to reduce the number of postoperative blood tests and the hospital length of stay for the patients who are not at risk of postoperative hypocalcemia.