Blood lead level and measured glomerular filtration rate in children with chronic kidney disease

Background: The role of environmental exposure to lead as a risk factor for chronic kidney disease (CKD) and its progression remains controversial, and most studies have been limited by a lack of direct glomerular filtration rate (GFR) measurement. Objective: We evaluated the association between lead exposure and GFR in children with CKD. Methods: In this cross-sectional study, we examined the association between blood lead levels (BLLs) and GFR measured by the plasma disappearance of iohexol among 391 participants in the Chronic Kidney Disease in Children (CKiD) prospective cohort study. Results: Median BLL and GFR were 1.2; μg/dL and 44.4; mL/min per 1.73; m², respectively. The average percent change in GFR for each 1--μg/dL increase in BLL was -2.1 (95% CI: -6.0, 1.8). In analyses stratified by CKD diagnosis, the association between BLL and GFR was stronger among children with glomerular disease underlying CKD; in this group, each 1--μg/dL increase in BLL was associated with a -12.1 (95% CI: -22.2, -1.9) percent change in GFR. In analyses stratified by anemia status, each 1--μg/dL increase in BLL among those with and without anemia was associated with a -0.3 (95% CI: -7.2, 6.6) and -4.6 (95% CI: -8.9, -0.3) percent change in GFR, respectively. Conclusions: There was no significant association between BLL and directly measured GFR in this relatively large cohort of children with CKD, although associations were observed in some subgroups. Longitudinal analyses are needed to examine the temporal relationship between lead and GFR decline, and to further examine the impact of underlying cause of CKD and anemia/hemoglobin status among patients with CKD.