Development of the fluorometric ELISA method for determination of alpha1-microglobulinuria in a cadmium-polluted area in Japan.
OBJECTIVE
To evaluate the usefulness of a newly developed fluorometric enzyme-linked immunosorbent assay (fluorometric ELISA) method for quantification of alpha1 -microglobulin (alpha1-m, protein HC) in an epidemiological study.


METHODS
Urinary alpha1-m in 37 female inhabitants in a cadmium-polluted area, including seven cases with Itai-itai disease, and ten inhabitants in a non-polluted area in Japan were examined. The alpha1-m was measured by both the fluorometric ELISA and a commercially available enzyme immunoassay (EIA) method to evaluate correlation of the two measurements. Concentration of beta2-microglobulin (beta2-m) was also determined in the same samples.


RESULTS
The detection limit of this method was 3 ng/ml or less of alpha1-m. A significant, high positive correlation was obtained between the alpha1-m concentrations measured with the fluorometric ELISA and that of EIA (r = 0.95, P < 0.0001). A significant association was also shown between the alpha1-m and beta2-m concentrations in the urine samples. The concentrations of urinary alphal-m of the inhabitants in the cadmium-polluted area (mean: 6.21 mg/l, 95% confidence interval (95% CI): 4.06-9.50 mg/l) were significantly higher than those of the reference area (mean: 2.19 mg/l, 95% CI: 1.90-2.67 mg/l). The urinary alpha1-m level of the Itai-itai patients was shown to be highest at 39.63 mg/l (95% CI: 28.27 55.55 mg/l). When the cut-off value of 10 mg/l was employed, alpha1-m had a sensitivity of 100% and specificity of 100% for Itai-itai disease.


CONCLUSIONS
These results suggest that this fluorometric ELISA is a useful tool to determine urinary alpha1-m in the epidemiological survey of renal tubular dysfunction, especially in the cadmium-polluted area of Japan.
Cai
Y
Y
Department of Public Health, Faculty of Medicine, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan.
Teranishi
H
H
Aoshima
K
K
Katoh
T
T
Arai
Y
Y
Kasuya
M
M
D000368:Aged; D000369:Aged, 80 and over; D000510:Alpha-Globulins / Q000652:urine*; D002104:Cadmium; D004785:Environmental Pollutants; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D005470:Fluorometry; D006801:Humans; D007564:Japan; D007674:Kidney Diseases / Q000652:urine; D007684:Kidney Tubules; D012680:Sensitivity and Specificity
D000510:Alpha-Globulins; D004785:Environmental Pollutants; C016001:alpha-1-microglobulin; D002104:Cadmium