Combined ionized calcium and PTH evaluation in the management of post-thyroidectomy hypocalcaemia.

BACKGROUND: Aim of our study was to investigate the postoperative course of calcium and parathyroid hormone (PTH) levels after total thyroidectomy to define a proper and low cost protocol.

METHODS: We studied 144 patients who underwent total thyroidectomy between 2007 and 2010. Ionized calcium was determined preoperatively and on day 1 (POD1), day 2 (POD2) and day 7 (POD7) postoperatively; PTH preoperatively and on POD7. Patients with ionized calcium ≤ 1.11 mmol/l were considered hypocalcaemic and treated only if symptoms, ≤ 1 mmol/l were treated in all cases.

RESULTS: Ionized calcium and PTH declined postoperative in all patients compared to preoperative levels (P=0.000). Ionized calcium increased on POD7 compared to POD1 and POD2 (P=0.000). All hypocalcaemic untreated tirthy patients returned normocalcaemic on POD7. Thirty- eight hypocalcaemic patients were treated but 23 (61%) safely suspended therapy on POD7. We tested PTH and ionized calcium as independent factors of prolongued hypocalcaemia (that required therapy beyond 7 days) with the following results (sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy): PTH ≤ 11 pg/ml (80,100,100,96 and 97%), ionized calcium ≤ 1.11 mmol/l (80,88,59,95 and 87%) and ionized calcium ≤ 1 mmol/l (28,100,100,87 and 88%).

CONCLUSIONS: Our data show that our protocol, including serum ionized calcium on 1st, 2nd, 7th days and PTH on 7th day after surgery, is safe and low cost and therefore may be useful in the post surgical management of total thyroidectomy.