Low-level lead exposure and the prevalence of gout: an observational study

Abstract

Background: Blood lead levels (BLLs) less than 1.21 µmol/L (<25 µg/dL) among adults are considered acceptable by current national standards. Lead toxicity can lead to gouty arthritis (gout), but whether the low lead exposure in the contemporary general population confers risk for gout is not known.

Objective: To determine whether BLLs within the range currently considered acceptable are associated with gout.

Design: Population-based cross-sectional study.

Setting: The National Health and Nutrition Examination Survey for 2005 through 2008.

Patients: 6153 civilians aged 40 years or older with an estimated glomerular filtration rate greater than 10 mL/min per 1.73 m2.

Measurements: Outcome variables were self-reported physician diagnosis of gout and serum urate level. Blood lead level was the principal exposure variable. Additional data collected were anthropometric measures, blood pressure, dietary purine intake, medication use, medical history, and serum creatinine concentration.

Results: The prevalence of gout was 6.05% (95% CI, 4.49% to 7.62%) among patients in the highest BLL quartile (mean, 0.19 µmol/L [3.95 µg/dL]) compared with 1.76% (CI, 1.10% to 2.42%) among those in the lowest quartile (mean, 0.04 µmol/L [0.89 µg/dL]). Each doubling of BLL was associated with an unadjusted odds ratio of 1.74 (CI, 1.47 to 2.05) for gout and 1.25 (CI, 1.12 to 1.40) for hyperuricemia. After adjustment for renal function, diabetes, diuretic use, hypertension, race, body mass index, income, and education level, the highest BLL quartile was associated with a 3.6-fold higher risk for gout and a 1.9-fold higher risk for hyperuricemia compared with the lowest quartile.

Limitation: Blood lead level does not necessarily reflect the total body lead burden.

Conclusion: Blood lead levels in the range currently considered acceptable are associated with increased prevalence of gout and hyperuricemia.