# Clinical significance and risk factors of incidental parathyroidectomy after total thyroidectomy

## TL;DR

This study shows that incidental parathyroidectomy after thyroid surgery increases the risk of low calcium and parathyroid hormone levels, with surgeon experience and additional neck surgery as key risk factors.

## Contribution

The study identifies surgeon experience and central neck dissection as significant risk factors for incidental parathyroidectomy after total thyroidectomy.

## Key findings

- Incidental parathyroidectomy was found in 21.8% of patients after total thyroidectomy.
- Patients with incidental parathyroidectomy had higher rates of postoperative hypoparathyroidism and hypocalcemia.
- Surgeon experience and central neck dissection were significant risk factors for incidental parathyroidectomy.

## Abstract

Postoperative hypoparathyroidism is the most common complication after total thyroidectomy(TT). The clinical significance of incidental parathyroid glands(IP) detected in pathological examination of removed surgical material is still controversial. The aim of this study was to evaluate the clinical follow-up findings and risk factors of patients with IP.

Postoperative pathology results and postoperative biochemical findings of patients who underwent TT±Central Neck Dissection(CND)/Lateral Neck Dissection(LND) between September,2020 and September,2023 in single institution were retrospectively evaluated. Patients with IP were divided into Group-1, and patients without IP were divided into Group-2. Patients of Group-1 were divided as Single IP and Double IP subgroups according to the number of IP.

The findings of a total of 412 patients were evaluated. IP was detected in 90(21.8%) of the patients. Postoperative hypoparathyroidism was more common in Group-1 at the 6th hour, 24th hour and 1st month postoperatively (69.7% vs. 31.7%, p < 0.0001; 61.1% vs. 27.7%, p < 0.0001, 26.2% vs. 12.2%, p = 0.002, respectively). Persistent hypoparathyroidism was observed at a rate of 5.3% in Group-2 and 11.5% in Group-1 (p = 0.041). Postoperative hypocalcemia was seen more frequently in Group-1 than in Group-2 at the 12th hour (34.4% vs. 23.2%, p = 0.031, respectively). There was no difference between Single IP vs. Double IP groups for the serum levels of Calcium and PTH. Among the risk factors evaluated for the detection of IP, in the univariance analysis, operation indications(p = 0.018), CND(p < 0.0001), surgeon experience(p = 0.016), thyroid gland volume(p = 0.02), preoperative serum TSH value(p = 0.031); in multivariance analysis, operation type ( ± CND) (OR:2.785; 95% CI: 1.175–6.605; p = 0.020) and operator experience between 10–20 years (OR: 0.117, 95% CI: 0.033–0.418, p = 0.001) and >20 years (OR: 0.254, 95%CI: 0.085–0.760, p = 0.014) were found significant compared to operators experienced <5 years.

Patients with detected IP after total thyroidectomy have lower postoperative Calcium and PTH. Significant risk factors for the IP were low level of surgeon experience and undergoing CND.