title: Prospective observation of 5-year clinical course of subclinical hypothyroidism in korean population.
abstract: Subclinical hypothyroidism (SCH) is a common clinical condition, whereas it's natural course has not been identified distinctly. We evaluated the natural history of 169 SCH patients over 5-yr and the prognostic factors including thyroid autoantibodies and thyroid ultrasonographic (USG) findings related to develop overt hypothyroidism. After 5 yr, 47.3% of patients showed normalization of TSH, while 36.7% of patients remained persistence of high level of TSH, and overt hypothyroidism developed in 11.2% of patients. There were painless thyroiditis (2.9%) and hyperthyroidism (1.7%) during 5 yr follow-up. The thyroid nodule was seen in 48.6% of patients. Most of patients had 1 to 2 nodules whereas only 3% of patients with thyroid nodule had more than 6 nodules. Overt hypothyroidism patients had more heterogenous echogenecity in USG compared to patients with normalization or persistent SCH (76.5% vs 50.0% vs 35.0%, P = 0.048) and higher prevalence positive anti-thyroid peroxidase (anti-TPO Ab) and anti-thyroglobulin antibody (anti-Tg Ab) and titer of anti-TPO Ab than other two groups. The cut off values for prediction of overt hypothyroidism were TSH > 7.45 µIU/mL, free T4 < 1.09 ng/dL and Anti-TPO Ab > 560 IU/mL. SCH has various courses and initial TSH, free T4, presence of thyroid autoantibody, titer of thyroid autoantibody; and thyroid USG findings can serve as a prognostic factor for progression of overt hypothyroidism. These parameters suggest consideration to initiate thyroid hormone treatment in SCH.
authors.affiliation: Department of Internal Medicine, Chungbuk National University School of Medicine, Cheongju, Korea.
authors.forename: Woo Ri
authors.initials: WR
authors.lastname: Park
authors.forename: Tae Keun
authors.initials: TK
authors.lastname: Oh
authors.forename: Hyun Jeong
authors.initials: HJ
authors.lastname: Jeon
mesh_terms: D058070:Asymptomatic Diseases / Q000453:epidemiology*; D001323:Autoantibodies / Q000097:blood / Q000276:immunology; D018450:Disease Progression; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000453:epidemiology; D007037:Hypothyroidism / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D056910:Republic of Korea / Q000453:epidemiology; D013954:Thyroglobulin / Q000276:immunology; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000276:immunology; D016606:Thyroid Nodule / Q000453:epidemiology; D013966:Thyroiditis / Q000453:epidemiology; D013972:Thyrotropin / Q000097:blood*
chemical_list: D001323:Autoantibodies; C006606:anti-thyroglobulin; D013972:Thyrotropin; D013954:Thyroglobulin
keywords: Hypothyroidism; Natural History; Subclinical Hypothyroidism