Abstract
Background
Postoperative hyperthyroidism occurs in approximately one third of patients following parathyroidectomy due to primary hyperparathyroidism (PHP), but has only rarely been described in secondary hyperparathyroidism (SHP). The frequency, course, and laboratory markers of postoperative hyperthyroidism in SHP remain unknown. Our purpose was to evaluate the frequency and the clinical course of postoperative hyperthyroidism following surgery of SHP and to determine the diagnostic value of thyroglobulin in this setting.Material and methods
A total of 40 patients undergoing parathyroidectomy because of SHP were included in this study. Thyroid stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), and thyroglobulin (Tg) were determined one day before and on day 1, 3, 5, 10, and 40 after surgery. At each of these visits patients were clinically evaluated for signs or symptoms of hyperthyroidism.Results
Biochemical evidence of hyperthyroidism was evident in 77% of patients postoperatively despite of preoperatively normal serum levels. TSH dropped from 1.18 ± 0.06mU/L to 0.15 ± 0.07mU/L (p = 0.0015). Free triiodothyronine (fT3) and fT4 levels increased from 2.86 ± 0.02ng/L and 10.32 ± 0.13ng/L, respectively, to their maximum of 4.83 ± 0.17ng/L and 19.35 ± 0.58ng/L, respectively. Thyroglobulin levels rose from 3.8 ± 0.8ng/mL to 111.8 ± 45.3ng/mL (pConclusion
Transient hyperthyroidism is frequent after parathyroidectomy for SHP with Tg being a suitable marker. Awareness of this self-limiting disorder is important to avoid inappropriate and potentially harmful treatment.