The Sixteenth Conference of the International Society for Environmental Epidemiology (ISEE): Abstracts
*Harvard School of Public Health and Harvard Medical School; †The Normative Aging Study, Department of Veterans Affairs Medical Center
In this prospective study, we examined changes in renal function over 6-years of follow-up in relation to baseline lead levels, diabetes, and hypertension among 448 middle-aged and elderly men, a sub-sample of the Normative Aging Study. Lead levels were generally low at baseline, with mean blood lead, patella lead and tibia lead values of 6.5 mcg/dl, 32.4 mcg/g, and 21.5 mcg/g, respectively. Six percent and 26% of subjects had diabetes and hypertension at baseline, respectively.
In multivariate-adjusted regression analyses, longitudinal increases in serum creatinine (SCr) were associated with higher baseline lead levels but these associations were not statistically significant. However, we observed significant interactions of blood lead and tibia lead with diabetes in predicting changes in SCr. For example, increasing the tibia lead level from the midpoints of the lowest to the highest quartiles (from 9 to 34 mcg/g) was associated with an increase in the rate of rise in SCr that was 17.6-fold greater in diabetics compared to non-diabetics (1.08 mg/dL/10 years v. 0.062 mg/dL/10 years; p<0.01). We also observed significant interactions of blood lead and tibia lead with diabetes in relation to baseline SCr levels (tibia lead only) and follow-up SCr levels. A significant interaction of tibia lead with hypertensive status in predicting changes in SCr was also observed. Increasing the tibia lead level from the midpoints of the lowest to the highest quartiles was associated with an increase in the rate of rise of SCr that was more than 50-fold greater in hypertensives than normotensives (0.31 mg/dL over 10 years versus 0.005 mg/dL over 10 years).
We conclude that longitudinal decline of renal function among middle-aged and elderly individuals appears to be dependent on both long-term lead stores and circulating lead with an effect that is most pronounced among diabetics and hypertensives, subjects who likely represent particularly susceptible groups.