Introduction:

Hypocalcemia due to hypoparathyroidism is the most frequent complication after total thyroidectomy. An important predictive factor of hypocalcaemia is postoperative parathormone (PTH), but the optimal time for testing PTH levels is under discussion.

Objectives:

The objective is to analyze the prognostic value of postoperative PTH at 24 hours as an indicator of hypocalcaemia, compared to serum calcium levels.

Methodology:

Descriptive retrospective observational study of 297 patients who underwent total thyroidectomy over an 8-year period. The patients were classified into 3 risk groups according to postoperative parathormone (high, medium and low risk). To compare parathormone versus postoperative calcium as a predictor of hypocalcemia, ROC curves and areas under the curve (AUC) were obtained.

Results:

The relative risk of having hypocalcemia with parathormone ≤ 15 pg/mL is 353.4 (p = 0.00). The postoperative parathormone test (≤ 15 pg / mL at 24h) obtained a sensitivity of 96.25% for the detection of hypocalcemia, specificity of 94.06% and global precision of 95.03%. The high-risk group (parathormone ≤ 15 pg/mL) accounts for the vast majority of patients with hypocalcemia and covers all permanent cases.

Conclusions:

Postoperative levels 24 hours after total thyroidectomy is a test with considerable prognostic value, capable of predicting the risk of postsurgical hypocalcemia. Patients with levels over > 15 pg/mL can be safely discharged.

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