Protein losses and nitrogen balance during continuous renal replacement therapy

Acute renal failure (ARF) is a highly catabolic state and mean normalized catabolic rates of 1.5 g/kg/day protein have been reported. In hemodynamically unstable ARF patients, continuous renal replacement therapy (CRRT) has become a popular treatment modality, but may have the disadvantage of producing substantial protein losses, reported to be as high as 1.3 g/l. In the USA and Europe, CRRT outputs reach 50 l/day, and this value would amount to protein losses of up to 65 g/day. ASPEN and ESPEN guidelines recommend that these patients should receive increased protein, up to a maximum of 2.5 g/kg/day, and that protein should not be restricted in patients with ARF as a means to avoid or delay initiation of dialysis therapy. But most previous studies were conducted in the era when energy requirements were adjusted by stress factors, and without intense glucose control therapy. So the optimal amount of protein supplementation in ARF patients in recent nutritional control is still unknown. In Japan, due to the limitation of doses of dialysate by health insurance it remains only 15 l/day, and protein losses are expected to be smaller than western countries. We measured the amount of nitrogen concentration in dialysate/ultrafiltrate samples, and calculated the nitrogen balance in such patients.