title: Blood lead levels and serum insulin-like growth factor 1 concentrations in peripubertal boys.
abstract: BACKGROUND
  Childhood lead exposure has been associated with growth delay. However, the association between blood lead levels (BLLs) and insulin-like growth factor 1 (IGF-1) has not been characterized in a large cohort with low-level lead exposure.
  
  
  METHODS
  We recruited 394 boys 8-9 years of age from an industrial Russian town in 2003-2005 and followed them annually thereafter. We used linear regression models to estimate the association of baseline BLLs with serum IGF-1 concentration at two follow-up visits (ages 10-11 and 12-13 years), adjusting for demographic and socioeconomic covariates.
  
  
  RESULTS
  At study entry, median BLL was 3 μg/dL (range, < 0.5-31 μg/dL), most boys (86%) were prepubertal, and mean ± SD height and BMI z-scores were 0.14 ± 1.0 and -0.2 ± 1.3, respectively. After adjustment for covariates, the mean follow-up IGF-1 concentration was 29.2 ng/mL lower (95% CI: -43.8, -14.5) for boys with high versus low BLL (≥ 5 μg/dL or < 5 μg/dL); this difference persisted after further adjustment for pubertal status. The association of BLL with IGF-1 was stronger for mid-pubertal than prepubertal boys (p = 0.04). Relative to boys with BLLs < 2 μg/dL, adjusted mean IGF-1 concentrations decreased by 12.8 ng/mL (95% CI: -29.9, 4.4) for boys with BLLs of 3-4 μg/dL; 34.5 ng/mL (95% CI: -53.1, -16.0) for BLLs 5-9 μg/dL; and 60.4 ng/mL (95% CI: -90.9, -29.9) for BLLs ≥ 10 μg/dL.
  
  
  CONCLUSIONS
  In peripubertal boys with low-level lead exposure, higher BLLs were associated with lower serum IGF-1. Inhibition of the hypothalamic-pituitary-growth axis may be one possible pathway by which lead exposure leads to growth delay.
authors: Department of Endocrinology, Children's Hospital Boston, Boston, Massachusetts, USA.
authors: Abby F
authors: AF
authors: Fleisch
authors: Jane S
authors: JS
authors: Burns
authors: Paige L
authors: PL
authors: Williams
authors: Mary M
authors: MM
authors: Lee
authors: Oleg
authors: O
authors: Sergeyev
authors: Susan A
authors: SA
authors: Korrick
authors: Russ
authors: R
authors: Hauser
mesh_terms: D002648:Child; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000097:blood*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007854:Lead / Q000097:blood*; D016014:Linear Models; D049449:Luminescence; D008163:Luminescent Measurements; D008297:Male; D012426:Russia; D013054:Spectrophotometry, Atomic
chemical_list: D004785:Environmental Pollutants; D007854:Lead; D007334:Insulin-Like Growth Factor I
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