June 26, 2003
(American Thoracic Society) -- Oral arginine, a non-toxic nutritional supplement with few side effects, reduced pulmonary hypertension by slightly over 15 percent after 5 days of therapy in 10 sickle cell disease patients, according to results of a study published in the first issue for July 2003 of the American Thoracic Society's peer-reviewed journal.
Writing in the American Journal of Respiratory and Critical Care Medicine, Claudia R. Morris, M.D., of the Department of Emergency Medicine, Children's Hospital Oakland, Oakland, California, along with 8 associates, pointed out that the enzyme arginase was elevated almost two-fold in patients with pulmonary hypertension. The researchers believe that this factor may limit arginine bioavailability in such patients.
"There has been growing evidence that pulmonary hypertension is a disease process involving altered arginine metabolism or decreased bioavailability," said Dr. Morris.
Sickle cell disease is an inherited condition that affects black persons almost exclusively. It is characterized by sickle-shaped red blood cells and chronic anemia. About 10 percent of black persons in the United States have one gene for sickle cell disease and do not develop the illness. A much smaller number have two genes and do develop the problem.
Pulmonary hypertension is a life-threatening complication of sickle cell disease that has been reported in 30 percent of patients. It involves an increase in blood pressure within the circulation. If it is not treated (treatment options are very limited), it can damage blood vessels, impair oxygen transfer in the blood, and stress the heart, causing potential heart failure. Its presence is an independent predictor of mortality in sickle cell disease patients; it can cause death in an average time of 12 months.
The investigators recruited 10 sickle cell patients with documented pulmonary hypertension for the study. The mean age of the patients was slightly over 32 and one-half. Four women were enrolled.
The researchers checked compliance with study medication by determining if there had been a significant rise at day 6 of plasma L-arginine levels. The one patient who was found non-compliant at the end of the study was the only individual who did not take the nutritional supplement and who did not show improvement in the pulmonary hypertension level.
Ten ethnically matched normal, non-sickle cell disease volunteers were enrolled in a control group to compare amino acid levels and arginine activity.
"This is the only study to date that has evaluated a potential new therapy for secondary pulmonary hypertension associated with sickle cell disease," said Dr. Morris. "Treatment options are limited and the prognosis is poor."
She noted that anecdotal evidence had been offered of treatment for the problem with vasodilators, anticoagulants, and transfusion therapy; however, all of these approaches remain unproven.
The investigators point out that blinded, controlled studies of longer duration for arginine therapy are needed to extend their preliminary findings and to determine the safety and efficacy of the supplement in sickle cell disease treatment.