Endocrine Abstracts

Introduction

Hypoparathyroidism (hypoPT) is one of the most complications after thyroid surgery, usually as transient hypocalcemia. Permanent hypoPT due to permanent parathyoid lesion, despite being less frequent, is associated to long term consequences for both objective and subjective well-being and should be prevented. Identifying predictive factors associated with post- thyroidectomy hypoPT is thereby crucial.

Aim

To investigate predictive factors for permanent hypoPT after total thyroidectomy(TT).

Materials and methods

This retrospective study enrolled patients submitted to total thyroidectomy in Centro Hospitalar e Universitário do Porto from January 2017 to June 2019. Patients without post-operative follow up were excluded. Postoperative hypoPT was defined by iPTH < 15 pg/ml, calcium levels < 2.15 mmol/l or patients’ requirement on daily vitamine D and calcium suplementation to avoid symptoms of hypocalcaemia. It was classified as permanent if parathyroid gland function has not recovered within six months after surgery. We investigated possible predictive factors for permanent postoperative hypoPT such as gender, age, thyroid specimen weight, histologic diagnosis of the specimen, presence of substernal goiter or autoimune thyroid disease, postoperative PTH and calcium levels.

Results

From a 357 total thyroidectomy procedures performed during the study’s period, two-hundred and fifty two patients were included for the analysis, with a higher predominance of the female gender (84.1%) and a mean age at thyroid surgery of 54.2 ± 13.6 years. Twenty patients patients with permanent hypoPT were identified (5.6% from all TT performed). A lower postoperative PTH level ( median 28.0 vs 49.0 pg/ml, P < 0.001), lower postoperative ( median 2.24 vs 2.38 mmol/l, P = 0.026) and 3-months postoperative calcium levels ( median 2.28 vs 2.36 mmol/l, P < 0.001) were associated with permanent hypoPT. Substernal goiter ( 16.1% vs 5.3%, P = 0.006) was also associated with permanent postoperative hypoPT. We did not found any statistically significant difference regarding risk for permanent hypoPT according to age (P = 0.61), gender (P = 0.60), thyroid specimen weight (0.12), autoimune thyroid disease (P = 0.38) or diagnosis of malignancy (P = 0.78).

Conclusions

In our current study, low postoperative PTH and calcium levels, and presence of substernal goiter were associated to permanent hypoPT. Understanding the factors associated with permanent HypoPT can assist in adequately monitoring these patients in the postoperative period and preventing hypocalcaemic events