Prevalence of hypoparathyroidism after thyroid surgery depending on diagnosis, the extent of the procedure, and the presence of parathyroid glands in the postoperative examination.

Abstract

Introduction Postoperative hypoparathyroidism can be one of the complications associated with total thyroid removal due to cancer or benign goitre. Purpose The paper aimed to evaluate the prevalence of hypoparathyroidism in patients operated on due to thyroid cancer and nodular goitre, including procedures performed between January 2015 and March 2019 at the Department of Oncological Surgery of the Medical University of Silesia in Katowice. Material and methods The studied group consisted of 595 patients operated on due to cancer and benign nodular goitres. Calcium and phosphate metabolism was assessed using PTH and ionised calcium tests four hours after the surgery. Ionised calcium was checked 30 days after the procedure. Patients who had borderline or below-normal PTH levels in the postoperative period were also subjected to PTH testing after 30 days. In patients with low PTH levels, supplementation with calcium and vitamin D3 was introduced after the surgery. Results Compared to patients operated on for benign goitres, persons diagnosed with cancer were significantly more likely to have PTH levels below 15 pg/ml and serum ionised calcium levels below 4 mg/dl after 30 days following the surgery. The recovery rate was 65.05% vs 82.6% (p < 0.003) and 64.2% vs 84.25% (p < 0.001). The results were similar among patients who underwent lateral and central lymphadenectomy - 33.3% vs 67.3% (p < 0.021) and 25.6% vs 67.6% (p < 0.018). In patients with mild goitres, no significant differences in the recovery rate were observed - 82.6% vs 92.8% (p < 0.327) and 84.25% vs 92.3% (p < 0.437). Patients in whom parathyroid glands were found in the postoperative material were significantly more likely to have decreased PTH and calcium levels after 30 days following the procedure. The recovery rate was 64.1% vs 78.9% (p < 0.027) and 58.06% vs 80.8% (p < 0.004). Conclusions Hypoparathyroidism is not an uncommon occurrence after thyroidectomy, even in facilities with extensive experience in this matter. Compared to total thyroid removal due to benign goitre, surgery for cancer with associated central and lateral lymphadenectomy significantly increases the risk of postoperative hypoparathyroidism. In surgical practice, it is reasonable to conduct routine Ca and PTH level checks after the procedure and 30 days following thyroidectomy.