ALPHA-1-MICROGLOBULIN - EPIDEMIOLOGIC INDICATOR FOR TUBULAR DYSFUNCTION INDUCED BY CADMIUM

Objectives-To evaluate the suitability of a-l-microglobulin as a marke r for cadmium induced renal dysfunction. Methods-alpha-1-Microglobulin was studied in a cross sectional survey in relation to the body burde n of cadmium. Concentrations of a-l-microglobulin in 24 h urine of 831 people aged 2-87 years were analysed in association with urinary cadm ium excretion, cadmium blood concentration, age, sex, occupational and smoking history, and estimated creatinine clearance. Participants cam e from a population residentially exposed to cadmium and from two cont rol populations matched for socioeconomic status. Results The excretio n of alpha-1-microglobulin 1 24 h ranged from 0.1 mg to 176.3 mg and 4 4.4% of samples showed concentrations near the detection limit. Ordina l logistic regression analysis of people of all ages identified a high risk only for males compared with females (odds ratio (OR) 2.14; 95% confidence interval (95% CI) 1.56 to 2.94), age group, and duration of Living on contaminated soil (OR 1.03 1 year; 95% CI 1.02 to 1.04), bu t not urinary cadmium excretion (OR 1.30; 95% CI 0.96 to 1.77) as sign ificant predictors. For people less than or equal to 50 years of age a weaker effect of sex (OR 1.76; 95% CI 1.13 to 2.73) and age group and an effect of similar magnitude for the duration of soil exposure (OR 1.03; 95% CI 1.01 to 1.04) were found. Also, the urinary cadmium excre tion (OR 2.26; 95% CI 1.38 to 3.70) and occupational exposure (OR 1.71 ; 95% CI 1.03 to 2.83) were found to be significant in this younger ag e group. The estimated creatinine clearance had no significant impact on the alpha-1-microglobulin excretion. Conclusion-alpha-1-Microglobul in is a suitable marker for early tubular changes only for people less than or equal to 50 years. It may not be sufficiently specific for ca dmium, and therefore not a suitable surrogate for cadmium exposure in epidemiological studies.