First of all, there are two areas where you can do blood tests:
1. For a differential diagnosis (looking what else it could be)
2. For judging ME/CFS
For the first area, there are some tests your doctor should do (if you haven't had these tests already), like test for hypothyroidism, celiac disease, allergies and so on. This should be more or less "standard fare" and your doctor should know these, and he should know which to pick depending on your symptoms.
For the second area, there are no "definitive" blood tests for ME/CFS. There are some blood tests that can be done but you need to have a doctor that can interpret them and knows what treatment to do. There is no "proven" treatment, so the few doctors that there are treating ME/CFS are each doing their own cocktail of treatments, each one has his/her own cause of ME/CFS and it is difficult taking the treatment from one doctor and teaching it to another...
I would do the following tests (not only blood):
- NK-cell function test (
http://jcm.asm.org/cgi/content/abstract/28/6/1403 and
http://dx.plos.org/10.1371/journal.pone.0010817 )
This should give you an indication if you have ME/CFS or something else. (If you take Vitamin D, this test might be meaningless, as VitD increases nk-cell function)
- Have a cortisol profile made. Many people with ME/CFS have a (more or less) flat profile, some too low in the morning, some too high in the evening. But there is no treatment options, this is just a blood test to "feel".
- Make a tilt-table test (maybe a poor-man's tilt-table test first). Maybe you have POTS/OI (
http://www.sciencedirect.com/science/article/pii/s1526-5900(09)00574-4 ), maybe some medication targeting alpha- or beta-receptors (low dose beta-blockers or maybe alpha-agonist) might help. A cardiologist could help, but its difficult to find a proper one.
- Test for all Herpes viruses (HSV-1, HSV-2, EBV, CMV, VZV, HHV-6). Some active herpes viruses have distinct symptoms (like blisters or zoster) you can look for and most of all, there are anti-virals that help some people with ME/CFS. (It only helps few, but hey!)
- Have a "neutralizing test" for coxsackie group B viruses (a subgroup of Enteroviruses). B3, B4 and B5 are the ones most likely. Then you could try Equilibrant by Dr. John Chia, see if it helps.
- Maybe try John Chia's test for Enteroviruses (but he needs a stomach biopsy and the test is expensive)
- Regarding XMRV, I personally would wait until the Lipkin study announces its result, which maybe will be this year.
It is an awful state of affairs...