Association of low-level blood lead with serum uric acid in U.S. adolescents: a cross-sectional study.

ABSTRACT

BACKGROUND: Uncertainty remains regarding the association between blood lead levels (BLL) and serum uric acid (SUA) with relatively low BLL exposure because of limited data in the adolescent population. We examined the association between BLL and SUA in U.S. adolescents. METHODS: In this cross-sectional study, 8303 adolescents aged 12-19 years from NHANES 1999-2006 were analyzed. BLL was Ln-transformed for analysis for the skewed distribution. Elevated SUA was defined as ≥5.5 mg/dL. Multivariate linear and multiple logistic regression analyses were performed to evaluate the association of BLL with SUA and elevated SUA. Moreover, a generalized additive model (GAM) and a fitted smoothing curve (penalized spline method) were conducted. RESULTS: The overall mean BLL was 1.3 µg/dL. Multivariate linear regression analyses showed that LnBLL was independently and positively correlated with SUA level (ß = 0.13, 95%CI 0.09-0.17). Multiple logistic analyses showed that LnBLL was associated with a 24% increased prevalence of elevated SUA (OR = 1.24; 95% CI, 1.11-1.38). Analyses using restricted cubic spline confirmed that the associations of LnBLL with SUA and elevated SUA were linear. Subgroup analyses showed that stronger associations between LnBLL and SUA were detected in adolescents with lower levels of education and estimated glomerular filtration rate (eGFR) (all P for interaction < 0.05). CONCLUSIONS: BLL was independently and positively correlated with SUA level and elevated SUA among U.S. adolescents, particularly with lower levels of education and eGFR. The data suggest that there is no "safe" threshold level of exposure to lead.