The effects of pathological and normal physiological processes on biopterin derivative levels in man.

Mean serum biopterin derivative levels in adult males and females were 1.75 microgram/l and 1.53 microgram/l respectively, increased with age and followed a cyclic pattern during menstruation. Foetal brain and liver levels at 16 weeks approximated adult concentrations. Wide distribution in adult tissues and variation in concentration independent of serum levels demonstrated local synthesis. Serum levels were significantly decreased in senile dementia, lead poisoning, coeliac disease and malignant carcinoid disease. Abnormal metabolism of phenylalanine in senile dementia suggest lowered levels of tetrahydrobiopterin in tissue. Methotrexate increased serum biopterin levels by inhibition of dihydropteridine reductase; a saturation effect was noted.