Problems concerning the usefulness of adjustment of urinary cadmium for creatinine and specific gravity.

A previous study concluded that there are some doubts as to the validity of creatinine as a parameter for adjusting the values of biological indicators determined on spot samples of urine, since it is subject to marked inter- and intraindividual variations. Furthermore, since there was only a moderate correlation between creatinine levels and specific density, it can be assumed that these two parameters cannot be used indifferently for adjustment. Nevertheless, it seemed advisable to verify whether correction of cadmium values determined from spot samples offers any practical advantages. For this purpose, 105 subjects with occupational exposure to cadmium were examined. They collected their 24-h urine and spot samples separately at 8.00 h. There was a close correlation between CdU/spot samples and CdU/24 h. The correlation index was very similar both for CdU/spot values expressed in microgram/l and for values adjusted according to creatinine or 1024 specific gravity. These results show that no particular advantages are offered by adjusting CdU according to creatinine or specific gravity.