[The alternative method for albuminuria determination: second morning urine sample instead of 24-hour urine...

Urinary albumin excretion is an established risk factor for renal and cardiovascular events. Measurement of albumin in the urine daily collection is the gold standard in assessing albuminuria. The 24-hour urine collection is cumbersome procedure that generates a lot of mistakes, therefore other methods have been proposed. The aim of the study was to compare the assessment of albuminuria in the 24-hour urine collection and in the second morning urine sample as well as to determine UACR.

The study included 32 patients, from whom the daily and the second morning urine samples were collected. In both samples, the albumin and creatinine concentrations were determined and the urinary albumin: creatinine ratio (UACR) was calculated.

An excellent correlation between the UACR determined from the 24-hour urine collection and the other portion of the second morning sample was obtained within a wide range of albuminuria values (r = 0.9825). Furthermore, a better correlation between the same characteristics was obtained in urine of patients with normoalbuminuria when UACR did not exceed 30 mg/g creatinine (r = 0.9771). Above this value, the correlation was slightly lower for micro- and macroalbuminuria and equalled 0.9249 and 0.9332, respectively.

On the basis of the obtained results it can be concluded that the second morning urine sample with the determination of UACR is a good alternative to the 24-hour urine collection and the first morning urine sample which are burdened with a preanalytical error.