No effects of hematuria and proteinuria in school days, and probably current pregnancy and current lactation also, as risk factors of cadmium-induced renal tubular dysfunction among adult women in general populations in Japan.

This study was initiated to examine if hematuria and proteinuria in school days, current pregnancy, or current lactation are risk factors of cadmium-induced tubular dysfunction for adult women among general populations in Japan. For this purpose, a database of 9,967 never-smoking adult women were reviewed for urinary levels of cadmium (Cd) and three other elements, calcium (Ca), magnesium (Mg), and zinc (Zn), and two tubular dysfunction markers of alpha1-microglobulin (alpha1-MG) and beta2-microglobulin (beta2-MG); the analyte concentrations were corrected for creatinine (cr) and expressed as, e.g., Cd-Ucr. From the total, 160 cases were selected as those who were informed of urinary abnormality (i.e., proteinuria, hematuria, or both) in their school days (the abnormality being found to be transient, later), and each case was matched by age and prefecture of residence. Separately, seven women with persistent urinary abnormality, seven pregnant women, and six lactating women were identified, and the case was matched with three cases each of the same age and living in the same prefecture. Statistical analyses showed that Cd-Ucr and other markers were not elevated in the transient urinary abnormality group as compared with the matched controls. This was also observed in the subjects with persistent abnormality. In the pregnant women, alpha1-MG-Ucr and possibly beta2-MG-Ucr were elevated, but Cd-Ucr did not increase, suggesting that the observed elevation in alpha1-MG and beta2-MG was not due to the effects of Cd but a part of the physiology of pregnancy itself. There was no change in marker levels in lactating women except for an increase in alpha1-MG. In overall evaluation, it was considered prudent to conclude that urinary abnormality in school days does not increase the risk of Cd-induced nephrotoxicity in adult women, whereas the negative findings with pregnancy and lactation should be taken as preliminary because the numbers of cases studied were limited.