title: Low maternal iodine intake and early pregnancy hypothyroxinemia: Possible repercussions for children.
abstract: OBJECTIVE
  Recent studies have shown that early pregnancy hypothyroxinemia (lower free thyroxin [FT4] and normal thyroid stimulating hormone [TSH] concentration) has deleterious effects on neuro-intellectual development of children. This study was designed to know its incidence in local pregnant women.
  
  
  METHODS
  Urinary iodine (UI) and serum thyroid related hormone (FT4, free triiodothyronine [FT3], and TSH) were determined in 254 pregnant women during the first trimester. UI and thyroid related hormones were determined by colorimetric (Sandell-Kolthoff) and radioimmunoassay method respectively.
  
  
  RESULTS
  Most of the pregnant women (n = 202; 79.5%) were iodine deficient (ID; UI <100 μg/L) and only 52 (20.5%) women were taking sufficient iodine (IS; UI ≥ 100 μg/L). Mean levels of FT4, FT3, and TSH were 13.0 ± 2.8 pmol/L, 3.8 ± 1.1 pmol/L and 1.2 ± 1.1 mIU/L, respectively. Maternal FT4 levels were significantly correlated with UI (r = 0.36; P < 0.001). Mean FT4 level in IS women was significantly (P < 0.05) higher than ID women. However, mean FT3 and TSH levels were not significantly different in both groups. FT4 reference range in IS pregnant women was 10.2-19.4 pmol/L. Hypothyroxinemia (FT4 <10.2 pmol/L and TSH <2.5 mIU/L) was diagnosed in 30 (11.8%) pregnant women. Its incidence was almost entirely confined to ID pregnant women with an odd ratio of 8.5 (95% confidence interval: 1.1-64.3).
  
  
  CONCLUSIONS
  About 12% pregnant women residing in urban areas of Pakistan are hypothyroxinemic because of low iodine intake.
authors.affiliation: Department of RIA and Biochemistry, Centre for Nuclear Medicine (CENUM), Mayo Hospital, Lahore, Pakistan.
authors.forename: Shan
authors.initials: S
authors.lastname: Elahi
authors.affiliation: Institute of Chemistry, New Campus, University of the Punjab, Lahore, Pakistan.
authors.forename: Saeed Ahmad
authors.initials: SA
authors.lastname: Nagra
keywords: Iodine; pregnancy; thyroid hormone; thyroid stimulating hormone