I think this is the Cheney observation (
http://www.dfwcfids.org/medical/cheney/heart04.part2b.htm). I started writing this about ESR last year but didn't post ...
I haven't had blood tests for years, but in all the tests I did have in the past, ESR was always 1mm/hr except for one occasional when it was 3mm/hr then back to 1mm/hr. I don't think I've been tested for plasma viscosity, I'm aware of most of the tests I've had, there may have been an occasion or two where I didn't have access to the test results eg during a GET program. There are many similar anecdotes from patients and doctors alike that ESR or SED (erythrocyte ie [red blood cell] sedimentation rate) is commonly very low in ME/CFS. I tried to find some sources for this:
However, I have not been able to find published studies which back these claims up about ME/CFS and low ESR. It is such a common test for routine medical assessment that there should be literally thousands of CFS studies with unpublished data on it. Yes, some ME and CFS patients have repeatedly tested very low ESR (0-3mm/hr), but from the limited amount of studies I have seen which do mention ESR (eg data from p124 of the original Canadian 2003 definition), this does not seem common enough to use as a litmus test, if anything it was slightly higher than healthy controls on average, with a standard deviation which would not suggest that lots of ME/CFS patients with lower ESR are being averaged out by lots of patients with higher ESR.
And shouldn't many of the possible causes of low ESR be detected in routine medical assessment and exclude one from a CFS diagnosis? Perhaps those of us with very low ESR do not have "CFS" but some underlying but undetected disease and we were dumped in the CFS wastebasket? Or perhaps ME commonly involves low ESR but CFS does not? I have purchased nattokinase and lumbrokinase for the hypothetical hypercoagulation but haven't really tested them yet. I once tried a dose of the former and coincidently noticed a similar sensation in the sinuses that I get from aspirin.