Total biopterin levels of plasma in patients with depression.

The total biopterin levels of plasma in 12 patients with depression were measured. They were elevated significantly as compared with those in normal controls. The plasma biopterin levels in 6 of 12 patients were measured both in the depressive and in the remissive phases. In the depressive phase the total biopterin levels were increased, whereas in the remission phase they did not differ from those in normal controls. Antidepressants did not affect the plasma biopterin levels. We speculate that the elevation of the plasma biopterin levels in patients with depression was related to the depressive state itself.