Dopamine (DA) is an endogenous catecholamine that influences receptors in a concentration-dependent manner. For >20 years, low-dose or “renal-dose” DA (LDD) (1 to 5 mcg/kg/min) has been used in an attempt to preserve renal function in critically ill patients. This use stems from studies that demonstrated increased renal blood flow and diuresis in healthy experimental animals and human volunteers. However, there have never been studies demonstrating benefit in critically ill patients, and recently, several high-quality studies have shown that LDD does not confer meaningful renal protection and indeed may cause harm.

LDD causes renal vasodilatation, predominately by stimulating DA-1 receptors in the renal vasculature. It causes natriuresis by inhibiting Na⁺/K⁺-ATPase activity in the proximal tubule, thick ascending limb of the loop of Henle, and the cortical collecting ducts. It causes diuresis by stimulating prostaglandin E₂ (PGE₂) production, which antagonizes the effects of antidiuretic hormone. These effects would appear to indicate improved renal function, but consideration of the patient and not the laboratory values suggests otherwise.

In a 1998 study of critically ill patients without renal or hepatic dysfunction, investigators found no correlation between DA infusion rate and DA serum concentration; serum concentrations in patients were significantly higher than in healthy controls. Thus the notion that LDD in healthy volunteers is the same as LDD in critically ill patients is highly questionable. The definitive study of LDD is a large multicenter, randomized, double-blind, placebo-controlled study performed by the Australian and New Zealand Intensive Care Society (ANZICS) Clinical Trials Group and published in 2000. It looked at 328 patients in 23 intensive care units (ICUs) and concluded that LDD does not benefit critically ill patients who are at risk for renal failure. The study demonstrated that LDD did not differ from placebo in resultant peak serum creatinine concentration, creatinine increase from baseline, number of patients requiring renal replacement therapy, duration of ICU stay, duration of hospital stay, and number of deaths. In another large trial, NORASEPT II study investigators performed a retrospective analysis of 395 oliguric patients with sepsis in the placebo arm of a TNF-α antibody sepsis trial and showed that LDD did not reduce the incidence of acute renal failure, the need for dialysis, or the 28-day mortality in patients with oliguria
due to septic shock. These same conclusions have been reached in several meta-analyses. The study data therefore do not support the hypothesis that LDD benefits patients with respect to the meaningful outcomes of death or dialysis.