Sustained-release l-arginine offers clinical benefits for children with sickle cell anemia, case-control study shows

Summary

This case-control study investigated the ability of sustained-release L-arginine supplementation to increase plasma levels of l-arginine and nitric oxide (NO) in children with sickle cell anemia.

The authors note that sickle cell disease (SCD), an autosomal recessive disorder, is a global public health problem of particular concern in sub-Saharan Africa as well as the most common genetic disease affecting African-Americans. L-arginine is the substrate for NO, the major endothelium-derived relaxing factor in normal physiology. A deficiency of l-arginine develops over time in patients with SCD, which is associated with complications of the disease.

For this study, the researchers enrolled 60 children (mean age 7 years, range 1-14 years) diagnosed with sickle cell disease (steady stage) as confirmed by homozygosity for hemoglobin-S, who presented to the sickle cell clinic unit of the Federal Teaching Hospital in Gombe, Nigeria.

The children were randomly assigned to treatment or to be an age- and gender-matched placebo control. Treatment consisted of sustained release l-arginine supplementation, providing 350 mg to 3,500 mg, twice daily, depending on body weight, for 8 weeks.

Baseline and 8-week follow up evaluations were completed for plasma levels of nitric oxide and L-arginine, as well as clinical outcome. The minimum sample size to detect differences in the outcome measures was determined to be 35 participants. Results were presented as mean +/- standard error. Student t-test and analysis of variance (ANOVA) were used for data comparison with differences considered significant at P<.05.

Results indicate that l-arginine supplementation significantly (P=.002) increased the mean plasma level of L-arginine after 8 weeks, compared to baseline (from 6.4 +/- 1.0 mmol/L to 45.9 +/- 1.3 mmol/L). Likewise, l-arginine supplementation significantly (P<.001) increased the mean plasma level of nitric oxide after 8 weeks, compared to baseline (from 2.0 +/- 0.4 mol/L to 48.2 +/- 2.5 mol/L). Plasma levels of l-arginine and nitric oxide were also found to be low in this patient population.

These findings suggest that supplementing with sustained-release l-arginine (350 mg to 3,500 mg, twice daily, for 8 weeks) helps restore normal plasma levels of l-arginine and nitric oxide in children with sickle cell anemia.

Study treatment and placebo products were provided by Endurance Products (Sherwood, Oregon).