[The practical assessment of micro-albuminuria as a marker for beginning diabetic nephropathy in: which urine sampling method?].

Microalbuminuria, i.e. elevated urinary albumin excretion rate between 20 and 200 micrograms/min, is a strong predictor of subsequent overt diabetic nephropathy. Screening for microalbuminuria is essential, since it has been shown that development of overt nephropathy can be delayed or even prevented by therapeutic measures such as strict metabolic control, early aggressive antihypertensive treatment, or restriction of protein intake. Several urine collection methods for the measurement of microalbuminuria have been proposed. In a prospective study with 40 diabetic outpatients we have compared albumin excretion in urine collected over 24 h, during a timed overnight period, and in a spot urine sample collected at random while the patient attended the outpatient clinic. In addition, the reproducibility of the three urine collection methods was assessed. For this purpose, each patient underwent 3 consecutive collections at an interval of at least 4 weeks. Our data indicate that calculation of an albumin/creatinine quotient in a spot urine probe is a reliable screening test for microalbuminuria. If this quotient is increased (greater than 2), timed overnight collection should be performed.