title: Hypothyroidism after Hemithyroidectomy: The Incidence and Risk Factors.
abstract: OBJECTIVE
  To evaluate the incidence of post-hemithyroidectomy hypothyroidism and identify possible risk factors that indicates whether patients require thyroid function monitoring after surgery.
  
  
  METHODS
  A retrospective review of patients with benign non-toxic thyroid disease undergoing hemithyroidectomy between April 2004 and November 2008 in the Department of Otorhinolaryngology, Siriraj Hospital was conducted All patients were in euthyroid state preoperatively. Thyroid specimens were examined for pathological diagnosis and degree of lymphocytic infiltration in thyroid tissue, and thyroid function was evaluated again six weeks after surgery.
  
  
  RESULTS
  One hundred patients who received hemithyroidectomy were recruited for the present study. All had normal preoperative thyroid function. Six weeks after surgery, 27% of the cases developed hypothyroidism (6% overt or symptomatic hypothyroidism and 21% subclinical hypothyroidism). The mean preoperative thyrotropin level was significantly higher in the hypothyroid group than in the euthyroid group (1.9±1.2 vs. 1.1±0.7 micro IU/ml). Fifty-eight point three percent of patients with preoperative thyroid stimulating hormone (TSH) level more than or equal 2 micro IU/ml developed hypothyroidism in comparison to only 17.1% of those with preoperative TSH <2 micro IU/ml (odds ratio 6.8). Fifteen patients had signifcant lymphocytic infiltration (grade 2-4); nine of those (60%) had post-operative hypothyroidism. In contrary, only 18 of 85 patients (21.2%) with minimal infiltrates (grade 0-1) developed hypothyroidism (odds ratio 5.6).
  
  
  CONCLUSIONS
  Twenty-seven percent of the patients in the present study developed hypothyroidism after hemithyroidectomy. Preoperative TSH more than or equal 2 micro IU/ml and significant lymphocytic infiltration in thyroid tissue or thyroiditis warrant post-operative close TSH monitoring. The awareness of such risk factors for post-operative hypothyroidism would improve patients care.
authors.forename: Chanticha
authors.initials: C
authors.lastname: Chotigavanich
authors.forename: Paiboon
authors.initials: P
authors.lastname: Sureepong
authors.forename: Sunun
authors.initials: S
authors.lastname: Ongard
authors.forename: Apaporn
authors.initials: A
authors.lastname: Eiamkulvorapong
authors.forename: Thiraphon
authors.initials: T
authors.lastname: Boonyaarunnate
authors.forename: Cheerasook
authors.initials: C
authors.lastname: Chongkolwatana
authors.forename: Choakchai
authors.initials: C
authors.lastname: Metheetrairut
mesh_terms: D000236:Adenoma / Q000601:surgery; D018249:Adenoma, Oxyphilic / Q000601:surgery; D000293:Adolescent; D000328:Adult; D000368:Aged; D003560:Cysts / Q000601:surgery; D005260:Female; D006042:Goiter / Q000601:surgery; D006785:Hospitals, University; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000453:epidemiology* / Q000209:etiology; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000097:blood / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D013785:Thailand / Q000453:epidemiology; D013959:Thyroid Diseases / Q000601:surgery*; D013964:Thyroid Neoplasms / Q000601:surgery; D013965:Thyroidectomy / Q000009:adverse effects / Q000379:methods; D013966:Thyroiditis / Q000601:surgery; D013972:Thyrotropin / Q000097:blood; D055815:Young Adult
chemical_list: D013972:Thyrotropin