Abstract
It has been difficult to determine the actual level of tetrahydrobiopterin (BH4) in plasma because of its extreme instability. The ratio of BH4 to total biopterin (BH4%) in plasma also decreases with time by unknown decomposition. We found that the addition of some reducing agents was effective to prevent the decomposition. Based on of these findings, we developed a procedure to add a reducing agent (ascorbic acid) to the blood collecting equipment.
Neopterin, total biopterin levels and BH4% in plasma from 69 healthy adults and 35 patients with hepatitis C were determined by the method described above and were compared with normal control values. The neopterin level was significantly higher, and BH4% was significantly lower in almost all patients than in control subjects. These finding indicate that virus infection influences not only the level of neopterin but also the level of BH4 in plasma.
