Urinary cadmium and age-related macular degeneration

PURPOSE: To evaluate the association between urinary and blood cadmium (Cd) levels with age-related macular degeneration (AMD). DESIGN: Prospective case,control study. METHODS: In 53 participants older than 60 years with AMD in both eyes and in 53 age-matched (+/- 3 years) controls without AMD, Cd levels were measured in blood and urine specimens (with and without creatinine adjustment) by using inductively coupled plasma-mass spectrometry. Data on age, gender, smoking status, and family history were obtained. By using color stereoscopic fundus photographs, the degree of AMD was graded using the Age-Related Eye Disease Study's 4-stage AMD severity scale. The inclusion criterion for AMD cases was a photographic severity level of two to four in both eyes. Median blood and urine Cd and median urine Cd/creatinine concentrations in cases and controls were compared by using the rank-sum test, stratifying for smoking status. RESULTS: Current and former smokers with AMD had median urine Cd/creatinine levels (1.18 mu g/g; range, 0.84 to 1.44 mu g/g) that were 97% higher than smokers without AMD (0.60 mu g/g; range, 0.49 to 0.90 mu g/g; P=.02), 111% higher than never smokers with AMD (0.56 mu g/g; range, 0.40 to 0.80 mu g/g; P <.001) and 107% higher than never smokers without AMD (0.57 mu g/g; 0.40 to 0.65 mu g/g; P <.001). Blood Cd levels, indicative of short-term exposure levels, were not associated with AMD (P <.06). CONCLUSIONS: A higher urinary Cd level, which reflects the total body burden of Cd, was associated with AMD in smokers. Accumulated Cd exposure may be important in the development of smoking-related AMD.