title: Spontaneous normalization of thyrotropin concentrations in patients with subclinical hypothyroidism.
abstract: BACKGROUND
  Patients with subclinical hypothyroidism may revert to normal TSH values.
  
  
  OBJECTIVE
  The objective of this study was to examine the time course of the normalization of TSH levels in subclinical hypothyroidism.
  
  
  METHODS
  This was a prospective, observational study with no intervention, with a duration of follow-up of 12-72 months.
  
  
  METHODS
  Outpatients visited an endocrinology clinic of a general hospital.
  
  
  METHODS
  Forty patients (32 women, mean age 62.8 +/- 8.2 yr) with spontaneous subclinical hypothyroidism (TSH > 5 mU/liter and normal free T(4)) participated in the study. Each patient normalized their TSH values without T(4) therapy throughout the follow-up.
  
  
  METHODS
  TSH and free T(4) levels were evaluated every 6 months.
  
  
  RESULTS
  Normalization occurred at a median time of 18 months (range, 6-60 months). Fifteen patients normalized their TSH levels during the first year of follow-up and 27 during the first 2 yr. Ten patients normalized their TSH values at the fourth or fifth year. Only four patients reverted to TSH values less than 2 mU/liter. Final TSH levels achieved by the patients were significantly correlated with the time elapsed until normalizing these levels (r = 0.367; P = 0.020).
  
  
  CONCLUSIONS
  There is no clear pattern of TSH normalization, although most patients normalize their TSH values early in the follow-up. The final TSH reached seems to be related to the time of normalization.
authors.affiliation: Department of Endocrinology, Hospital Ramón y Cajal, Carretera Colmenar km 9, 28034 Madrid, Spain. mibarsd@infomed.es
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Díez
authors.forename: Pedro
authors.initials: P
authors.lastname: Iglesias
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Burman
mesh_terms: D000368:Aged; D001323:Autoantibodies / Q000097:blood; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood*; D007453:Iodide Peroxidase / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D013972:Thyrotropin / Q000097:blood*
chemical_list: D001323:Autoantibodies; D013972:Thyrotropin; D007453:Iodide Peroxidase