June 22, 2000
Amino acid supplements may provide a cost-effective and safe method for improving the nutritional intake of some dialysis patients who are unable to meet their daily protein requirements, a Johns Hopkins study shows.
"The technique increases serum proteins toward normal levels," says Mackenzie Walser, M.D., senior author of the study and professor of medicine, pharmacology and molecular science at Hopkins.
Dialysis patients have low levels of protein in their blood compared to healthy individuals. Patients can't always increase the level of protein in their diet because of complications of kidney failure: a persistent poor appetite, the need for numerous medications, ongoing inflammation and related medical problems. Yet supplements of amino acids – fundamental components of all proteins – bypass these problems and are a good way to increase proteins in the blood, the authors say.
Hypoalbuminemia, or lack of sufficient protein in the blood, affects up to 40 percent of dialysis patients and is the strongest predictor of death in dialysis patients, they say. Nutritional interventions are desperately needed, Walser adds, because nearly 23 percent of dialysis patients die each year, often in association with low albumin levels.
Previous studies of dialysis patients have looked at intravenous methods of delivering amino acids, which are much more expensive. The current study, published in the June issue of the journal Kidney International, is the first randomized, double-blind controlled trial of oral supplements in this population.
"The amino acid pills were well tolerated," says Joseph A. Eustace, M.D., lead author of the study and an instructor of medicine at Hopkins. "Our work shows that simple nutritional interventions have the potential to do dialysis patients a lot of good."
Researchers studied the effects of amino acid supplements in 47 patients, 29 of whom were on hemodialysis and 18 on peritoneal dialysis. In the first method, a patient's blood is directly filtered of waste materials. In the latter, fluid is injected through a soft tube in the abdominal wall to remove toxins, and is replaced several times a day.
During the study, patients were randomly assigned to take either five amino acid pills (3.6 g) or five placebo pills with meals three times a day for three months. Albumin levels were measured at the end of each month.
At the study's conclusion, hemodialysis patients who took amino acids saw their albumin levels raised by an average of 0.22 g/dL. Peritoneal dialysis patients had an average increase of only 0.01 g/dL.
"We hope that this increase in serum albumin will result in better health and increased survival for patients treated with hemodialysis," Eustace says. Another ongoing study is measuring the effects of fewer supplements on albumin levels, he says. Further study will investigate how the amino acids increase serum albumin levels.
Eustace was supported by the National Institutes of Health. Additional study support was provided by Recip AB Arsta, Sweden. Walser is entitled to a share of royalties received by the University on sales of the product described in this article. The terms of this arrangement are being managed by The Johns Hopkins University in accordance with its conflict of interest policy.
Other authors of the study were Josef Coresh, Ph.D.; Chris Kutchey, R.D.; Purita L. Te, R.D.; Luis F. Gimenez, M.D.; and Paul J. Scheel, Jr., M.D.
Related Web Sites:
National Kidney Foundation:
National Institute of Diabetes & Digestive & Kidney Diseases: