Detection of Elevated Level of Tetrahydrobiopterin in Serum Samples of ME/CFS Patients with Orthostatic Intolerance: A Pilot Study


Senior Member
They should measure the neurotransmitters because maybe Bh4 isn't being used to form neurotransmitters and is just floating around in the blood stream.

"BH4 is an important cofactor of amino acid metabolism [8]. Amino acids, such as phenylalanine, tyrosine, and tryptophan, are converted into important cellular intermediates by the action of hydroxylase enzymes. BH4 serves as an essential cofactor of all these hydroxylase enzymes [9,10,11]. Accordingly, the bioavailability of BH4 is critical for the synthesis of neurotransmitters, such as dopamine and serotonin [10]. Apart from these hydroxylase enzymes, BH4 also regulates the function of nitric oxide synthase enzymes and controls the production of nitric oxide (NO) in endothelium."

Are they going to go anywhere with the oxidative stress mentioned in the article?

"Finally, a ROS production assay in cultured microglial cells followed by Pearson correlation statistics indicated that the elevated BH4 in serum samples of CFS + OI patients might be associated with the oxidative stress response."


Senior Member
To me it seems plausible the body is making extra bh4 because to make up for for reduced endothelial function caused by some other problem or deficiency. High levels of bh4 would be compensatory.
Given the intersection of Rob Phair's and Bhupesh Prusty's work I think there is also a possibility its not being taken up by the cells that need it due the lockdown state the cells are in. The body is producing the material and its not getting taken up resulting in an excess in the blood and the feedback loop is not tight for certain materials in the blood that don't need very precisely control.

The other possibility is its leaking out of/being ejected from the cells.