alpha-1-Microglobulin: epidemiological indicator for tubular dysfunction induced by cadmium?
OBJECTIVE
To evaluate the suitability of alpha-1-microglobulin as a marker for cadmium induced renal dysfunction.


METHODS
alpha-1-Microglobulin was studied in a cross sectional survey in relation to the body burden of cadmium. Concentrations of alpha-1-microglobulin in 24 h urine of 831 people aged 2-87 years were analysed in association with urinary cadmium excretion, cadmium blood concentration, age, sex, occupational and smoking history, and estimated creatinine clearance. Participants came from a population residentially exposed to cadmium and from two control populations matched for socioeconomic status.


RESULTS
The excretion of alpha-1-microglobulin/24 h ranged from 0.1 mg to 176.3 mg and 44.4% of samples showed concentrations near the detection limit. Ordinal 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/year; 95% CI 1.02 to 1.04), but not urinary cadmium excretion (OR 1.30; 95% CI 0.96 to 1.77) as significant predictors. For people < or = 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 excretion (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 age group. The estimated creatinine clearance had no significant impact on the alpha-1-microglobulin excretion.


CONCLUSIONS
alpha-1-Microglobulin is a suitable marker for early tubular changes only for people < or = 50 years. It may not be sufficiently specific for cadmium, and therefore not a suitable surrogate for cadmium exposure in epidemiological studies.
Pless-Mulloli
T
T
Department of Epidemiology and Public Health, School of Health Sciences, University of Newcastle upon Tyne, UK.
Boettcher
M
M
Steiner
M
M
Berger
J
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000510:Alpha-Globulins / Q000652:urine*; D015415:Biomarkers / Q000652:urine; D002104:Cadmium / Q000009:adverse effects* / Q000097:blood / Q000652:urine; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D015991:Epidemiologic Measurements; D005260:Female; D006801:Humans; D007674:Kidney Diseases / Q000139:chemically induced* / Q000378:metabolism / Q000503:physiopathology; D007684:Kidney Tubules / Q000187:drug effects* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects; D012989:Soil Pollutants; D013997:Time Factors
D000510:Alpha-Globulins; D015415:Biomarkers; D012989:Soil Pollutants; C016001:alpha-1-microglobulin; D002104:Cadmium