1 From the Departments of Radiology (Division of Nuclear Medicine), Pediatrics, and Biometry, Emory University School of Medicine and Henrietta Egleston Hospital for Children, Atlanta
To determine the effect of cystic fibrosis on the regulation of plasma pyridoxal 5'-phosphate (PLP), the biologically active form of vitamin B6, we measured this compound in plasma from 56 patients with cystic fibrosis. The concentration of PLP in plasma was assayed by a radioenzymatic technique. The results of this study showed that PLP concentration was decreased significantly (6.44 ± 5.20 ng/mL, mean ± SD; median 4.45 ng/mL) in patients with cystic fibrosis as compared with a group of hospitalized children with neither cystic fibrosis nor hepatic disease serving as a control group (13.2 ± 5.04 ng/mL, mean ± SD; median 12.5 ng/mL). Additionally, 25% of the population with cystic fibrosis exhibited exceedingly low plasma PLP level (less than 2.75 ng/mL). In patients with cystic fibrosis, significant inverse linear associations were found between plasma PLP and serum levels of SGOT and SGPT (PLP v SGOT: r = -. 60, P < .03; PLP v SGPT: r = -.50, P < .03). This study demonstrated that a deficiency of plasma PLP is a common abnormality in cystic fibrosis and that the low PLP level may be a reflection of impaired vitamin B6 metabolism associated with this disorder.
Key Words: cystic fibrosis vitamin B6 pyridoxal 5'-phosphate malnutrition liver disease radioenzymatic technique
Submitted on August 28, 1985
Accepted on November 25, 1985