Vitamin B-6 status of school-aged patients with phenylketonuria.
A triad of measures of vitamin B-6 (B6) status (diet, plasma, and urine) was evaluated in 15 patients with phenylketonuria (PKU) and six control subjects (6-17 y): 1) 4-d reported dietary intakes of protein and B6; 2) fasting plasma concentrations of pyridoxal 5'-phosphate (PLP), total B6 (TB6), and alkaline phosphatase (AP) activity; and 3) 24-h urinary excretions of TB6 and 4-pyridoxic acid (4-PA). Compared with control subjects, patients had a significantly reduced mean protein intake (P < 0.001) and increased mean B6 intake (P < 0.05). Mean dietary B6:protein in patients, 0.043 mg/g protein, was over twice that of control subjects, 0.018 mg/g protein (P < 0.001). Mean plasma PLP and PLP/TB6 in patients were significantly increased compared with control subjects (P < or = 0.05). As a percent of B6 intake, mean urine TB6 was similar between the groups (6.8% patients vs 6.5% control subjects). These findings, along with a lower mean plasma AP activity in patients, support the possibility of a reduced turnover of the vitamin in PKU.
Child Development and Rehabilitation Center, Oregon Health Sciences University, Portland.
A P
AP
Prince
J E
JE
Leklem
D000293:Adolescent; D000469:Alkaline Phosphatase / Q000097:blood; D002648:Child; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008297:Male; D010649:Phenylalanine / Q000008:administration & dosage / Q000097:blood; D010661:Phenylketonurias / Q000378:metabolism*; D011732:Pyridoxal Phosphate / Q000097:blood; D011735:Pyridoxic Acid / Q000652:urine; D011736:Pyridoxine / Q000008:administration & dosage* / Q000097:blood / Q000652:urine
D004044:Dietary Proteins; D010649:Phenylalanine; D011735:Pyridoxic Acid; D011732:Pyridoxal Phosphate; D000469:Alkaline Phosphatase; D011736:Pyridoxine