Very high protein in CSF. Is that normal?

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I had a lumbar puncture done to test for intracranial hypertension. I had double vision and mild optic disc swelling. Pressure was a bit elevated, as expected. But then the lab result came back with 1.3g/l protein (normal <0.45g/l). I keep being told this is normal, but everywhere I read online says it's not. 1.3 seems exceptionally high, too.

I'm mostly dealing with cogintive difficulties and severe depression. I haven't been able to do anything for over a year now. I keep being sent to different psychiatrists but their meds only make it worse and they all seem equally clueless. Therapy has been unsuccessful as I can barely talk most of the time. My doctor is still convinced it's all psychological and won't run any more tests.

My questions are, how "normal" is this? How many normal people have such high protein values. What conditions should be ruled out, what other tests can be done? How do I convince my doctor I'm not crazy?