Postsurgical hypoparathyroidism: Identification of the high-risk patient. A comparison between the ATA protocol and the SEORL-CCC/SEEN consensus

Introduction

Parathyroid hormone (PTH) levels are the most reliable parameter to identify patients with a high risk of post-thyroidectomy hypoparathyroidism. The American Thyroid Association (ATA) developed a consensus where postoperative iPTH (PTHpost) <15 pg/mL suggests a significant risk for hypoparathyroidism. The Spanish Society of Otolaryngology and Head & Neck Surgery (SEORL-CCC) identifies high-risk patients as those with a decrease of preoperative-postoperative PTH levels (PTHdecr) ≥80%. A comparison of the accuracy of both protocols is made.

Materials and methods

An analysis was conducted on all patients who underwent total or completion thyroidectomy over 10 years. A preoperative PTH (PTHpre) and a postoperative PTH (PTHpost) sample were collected. Postsurgical hypoparathyroidism was defined as the presence of hypocalcemia signs or symptoms, or calcium lower than 7 mg/dL in serum levels or 0.95 mmol/L in ionic levels. No patient received treatment without meeting our definition.

Results

711 patients were included. 19% of patients suffered from hypoparathyroidism. The PTHdecr demonstrated a ROC curve with an AUC of 0.98. iPTHpost demonstrated a ROC curve with an AUC of 0.97. The PTHdecr was found to have a statistically superior AUC compared to the PTHpost (p = 0.002). Considering cutoff levels of 80% for iPTHdecr and 15 pg/mL for PTHpost, no statistical differences were found between the sensitivity of both protocols (93% and 95% respectively), but the same cutoff levels showed a superior specificity of PTHdecr (95%) than PTHpost (86%).

Conclusions

SEORL-CCC protocol, which relies on PTHdecr, has demonstrated superior diagnostic accuracy. The cutoff level used showed a superior specificity without sacrificing its sensitivity.