Reduced antioxidant capacity in paediatric patients with homozygous sickle cell disease.

The sickled erythrocyte has been shown to be susceptible to lipid peroxidation and a role has been suggested for antioxidants in this process. The present study was undertaken in 22 children, aged 5-18 years with homozygous sickle cell disease (SS) and 9 HbAA controls (AA) of similar age. All the SS patients were in steady state ie, not in crisis or any acute illness at the time of the study. Levels of plasma tocopherol, retinol, carotenes and ascorbic acid (antioxidant vitamins of major nutritional importance) were measured. Plasma tocopherol carotenes and retinol were measured by HPLC after extraction into heptane. Total ascorbic acid (in trichloroacetic acid extracts of plasma) was measured colorimetrically following reaction with 2,4-dinitrophenylhydrazine. Riboflavin status was measured by the glutathione reductase activation test. Levels of all the measured antioxidants except ascorbate were reduced in SS patients compared with control children but only plasma alpha-tocopherol concentration was significantly different between the patients and controls. The median tocopherol level in SS patients (11.32 mumol/l) was significantly lower (P less than 0.02 Mann-Whitney) than that in control children (18.02 mumol/l) when measured directly or when calculated from tocopherol: cholesterol ratio, 4.55 mumol/mmol in SS patients and 7.50 mumol/mmol in control children. The median concentration of total plasma carotenes of SS patients (5.67 mumol/l) was lower than that of control children (12.14 mumol/l). Similarly, plasma beta-carotene concentration of SS patients was lower than that of control children but the difference in each case was not significant. Despite this, the vitamin A status (plasma retinol concentration) of SS patients was poorer than that of control children.(ABSTRACT TRUNCATED AT 250 WORDS)