[Low dosage dopamine improves kidney function: current status of knowledge and evaluation of a controversial topic].

The ability of low dose dopamine (1-3 micrograms x kg-1 x min-1) to cause selective renal vasodilation, to increase glomerular filtration rate, urine output, and natriuresis, is intuitively considered favourable. Dopamine, therefore, continues to be used in critically ill patients to preserve or improve renal function. Despite its application in a wide variety of disease states and in patients at risk of acute renal failure or with already decreased renal function, there is no conclusive evidence that "renal doses" of dopamine prevented acute renal failure or had any positive effect on patient outcome although it increased urine output and natriuresis consistently. Data from many clinical studies, however, are difficult to interpret due to small numbers of patients, the absence of control groups, the inability to exclude changes in cardiac output or to separate a diuretic effect of dopamine in the tubulus system from specific increases of glomerular filtration rate, and because of the variability of methods to determine renal performance (i.e. creatinine clearance, urine output, natriuresis, fractional excretion of sodium). Moreover, the routine use of dopamine is not innovous, since it may worsen gut ischaemia and suppress certain hormonal systems. Those who believe in the clinical benefits of "renal dose" dopamine argue that, even in the absence of an improvement in renal function, the maintenance of urine output could be useful in patients unresponsive to diuretics. Again, the clinical benefit of this diuretic action still needs to be shown. In conclusion, there is little justification for the routine administration of low-dose dopamine in patients at risk of renal failure. Large controlled clinical studies are urgently needed to determine whether dopamine improves renal function or prevents acute renal failure in patients at risk.