Vitamin B₆ status of children with sickle cell disease

Purpose: In vitro, vitamin B₆ has antisickling properties, but the effect of vitamin B₆ status on the health of children with sickle cell disease-SS (SCD-SS) is not well described. The purpose of this study was to assess vitamin B₆ status of children with SCD-SS ages 3 to 20 years and determine its relationship to growth, dietary intake, and disease severity. Patients and Methods: Vitamin B₆ status was assessed by serum pyridoxal 5-phosphate (PLP) concentration in subjects with SCD-SS and by urinary 4-pyridoxic acid (4-PA) concentration in other subjects with SCD-SS and healthy control children. Concentration of PLP was compared with anthropometric measures of growth and nutritional status, dietary intake, hematologic indices, and frequency of SCD-related illness. Results: The PLP concentration of subjects with SCD-SS was 15.6 ± 15.2 nmol/L. Seventy-seven percent had a PLP concentration below the deficiency criterion (20 nmol/L) suggested by the Dietary Reference Intakes (1998). Controlling for alkaline phosphatase, age, and gender, PLP concentration was associated positively with weight, body mass index, and arm circumference z-scores and negatively with reticulocyte count. Urinary 4-PA was lower in children with SCD-SS versus controls, although 4-PA/creatinine values did not differ between groups. Conclusions: Children with SCD-SS had apparently low serum PLP concentrations in the absence of excess vitamin B₆ excretion, suggesting low vitamin B₆ status. Low serum PLP concentration was associated with indicators of poor nutritional status and may be related to increased hemolysis in children with SCD-SS.