Tetrahydrobiopterin Loading Test in Xanthine Dehydrogenase and Molybdenum Cofactor Deficiencies

The objectives of this study were to find additional diagnostic information for the evaluation of xanthine dehydrogenase deficiency and molybdenum cofactor deficiency. Patients were given an oral loading test with 10 mg/kg 5,6,7,8-tetrahydrobiopterin. Urine excretion of pterin and isoxanthopterin wa...

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Bibliographic Details
Published in:Biochemical and molecular medicine 1996-08, Vol.58 (2), p.199-203
Main Authors: Blau, N., de Klerk, J.B.C., Thöny, B., Heizmann, C.W., Kierat, L., Smeitink, J.A.M., Duran, M.
Format: Article
Language:English
Subjects:
Administration, Oral
Adult
Antioxidants
Biopterins - administration & dosage
Biopterins - analogs & derivatives
Biopterins - metabolism
Biopterins - urine
Child, Preschool
Coenzymes
Female
Heterozygote
Humans
Infant
Infant, Newborn
Male
Metabolism, Inborn Errors - diagnosis
Metabolism, Inborn Errors - genetics
Metalloproteins - metabolism
Middle Aged
Molybdenum Cofactors
Pregnancy
Pteridines - metabolism
Pterins - metabolism
Pterins - urine
Xanthine Dehydrogenase - deficiency
Xanthine Dehydrogenase - metabolism
Xanthopterin - metabolism
Xanthopterin - urine
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Summary:The objectives of this study were to find additional diagnostic information for the evaluation of xanthine dehydrogenase deficiency and molybdenum cofactor deficiency. Patients were given an oral loading test with 10 mg/kg 5,6,7,8-tetrahydrobiopterin. Urine excretion of pterin and isoxanthopterin was measured by HPLC. Control subjects had a fairly constant ratio of urinary pterin/isoxanthopterin before (0.57–5.32) and after (0.55–4.55) 5,6,7,8-tetrahydrobiopterin loading. These ratios were increased to 33 and 22 in a patient with hereditary xanthinuria and to 570 and 8030 in a patient with molybdenum cofactor deficiency. Obligate heterozygotes had an entirely normal test result. Evidence was obtained for thein vivoinvolvement of xanthine dehydrogenase in the conversion of pterin to isoxanthopterin. This test could be a sensitive marker for the establishment of residual enzyme activity.
ISSN:1077-3150
1095-5577
DOI:10.1006/bmme.1996.0049