Incidence of transient and chronic hypoparathyroidism after total thyroidectomy - the experience of a tertiary center.

Background: The most common cause of hypoparathyroidism (hypoPT) in adults is iatrogenic due to total thyroidectomy, while the ideal moment for considering it chronic is still under debate. Our study aims at reporting the prevalence of transient and permanent hypoPT following thyroid surgery in a tertiary surgical center, as well as serum Parathormone (PTH) variation up to 12 months after surgery stratified according to the type of thyroid disease.

Material and methods: 519 patients who underwent total thyroidectomy in a tertiary surgical center from 2018 to 2023 were analyzed. Postoperative hypoPT was defined as low PTH (less than 15 pg/ml) and/or hypocalcemia (albumin-corrected levels less than 8.5 mg/dl) on day 1 after surgery. Patients were considered to have permanent hypoPT if they had not recovered completely within 1 year after total thyroidectomy. PTH levels were compared according to the underlying thyroid disease.

Results: 140 patients (26.97%) had postoperative hypoPT. Twenty-two patients (4.23%) were considered to have permanent hypoPT 12 months after surgery. Approximately half of the patients recovered between 3 months and 12 months after surgery. HypoPT thyroiditis patients had higher PTH levels 3 months after surgery compared to papillary/follicular cancer and multinodular goiter, respectively, and all recovered 1 year after surgery. Papillary/follicular carcinoma was associated with a 29.4% rate of transient and 8.5% rate of chronic hypoPT, respectively.

Conclusion: Most patients without incidental parathyroidectomy that still develop postoperative hypoPT will eventually recover; nevertheless, it can take up to 1 year for full resolution. Measuring serum PTH 3 months postoperative may be of interest.