Yup, I meant high tsh = hypo. Brainfog, y'know.
To Gondwanaland, kynurenines are the result of tryptophan conversion. Our cells convert TRP into several types of kynurenines, which are needed for various purposes. When our immune systems are active, the cytokines increase the conversion into kynurenines. Some of them, such as quinolinic acid, are probably responsible for some of the symptoms of inflammation: malaise, lethargy, pain, and suicidal moods. Picolinic acid elevates macrophage inflammatory proteins, which in turn elevate trh, and thus tsh. My cytokine profile did show elevated MIPs, and while that's not proof that picolinic acid was elevated (there might be other causes), it should explain elevated tsh.
In the early days of this disorder, long before I read about ME/CFS, I assumed it was some rare form of chronic inflammation, which would cause elevated IFN-g, which would elevated indole oxidase, which would catalyze more TRP into kynurenines. That was simple and logical. I had various observations, such as my response to TRP and exercise (which increases IFN-g 24 hrs later) that supported this hypothesis. Later I observed that sugars and starches would increase symptoms about 20 minutes later...unless I took BCAA's with the meal. Sugars and starches increase insulin, which increases TRP transport into the brain, where they'd convert into kynurenines. It still seems a logical explanation to me, and I haven't found any strong counter-evidence.
I tried a low-TRP diet for a long time, but it's hard to avoid TRP completely, and the body must keep larger reserves of it, since I didn't manage to feel better. High-TRP foods did make me feel worse, and TRP tablets made me strongly suicidal. If high-TRP foods make you feel worse, or insulin-boosting foods make you feel worse 20 minutes later, then I'd consider that more evidence that kynurenines are a significant factor in ME/CFS symptoms.
I'd like to try one of the drugs that alter kynurenine conversion, but they're not available for human use. They sound fairly safe, but no one has gotten them through the approvals process yet.