title: Transient hyperthyroidism after surgery for secondary hyperparathyroidism: a common problem.
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.
  
  
  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 (p<0.001). At day 40 all thyroid related laboratory values were within normal range. Correlation analysis of postoperative values revealed significant correlations for lowest TSH (r = -0.32; p = 0.038), and highest fT3 (r = 0.55; p<0.001) and fT4 levels (r = 0.67; p<0.001) with Tg.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Division of Endocrinology and Clinical Chemistry, Department of Medicine, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany. gottfried_rudofsky@med.uni-heidelberg.de
authors.forename: Gottfried
authors.initials: G
authors.lastname: Rudofsky
authors.forename: M
authors.initials: M
authors.lastname: Tsioga
authors.forename: P
authors.initials: P
authors.lastname: Reismann
authors.forename: C
authors.initials: C
authors.lastname: Leowardi
authors.forename: S
authors.initials: S
authors.lastname: Kopf
authors.forename: I A
authors.initials: IA
authors.lastname: Grafe
authors.forename: P P
authors.initials: PP
authors.lastname: Nawroth
authors.forename: B
authors.initials: B
authors.lastname: Isermann
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000150:complications / Q000378:metabolism / Q000601:surgery*; D006980:Hyperthyroidism / Q000150:complications / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011446:Prospective Studies; D013514:Surgical Procedures, Operative / Q000009:adverse effects; D013954:Thyroglobulin / Q000378:metabolism; D013972:Thyrotropin / Q000378:metabolism; D013974:Thyroxine / Q000378:metabolism; D013997:Time Factors; D014284:Triiodothyronine / Q000378:metabolism
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D013954:Thyroglobulin; D013974:Thyroxine