Hi kstone,
ALL of my inflammatory markers came back within the standard range. RA factor, SED, Protein, CRP, etc. I was diagnosed with PsA based on MRIs and the pitting in my nails. And it turned out to be the correct diagnosis because my pain went away just a day after my first Humira injection. There were times when i wondered if I REALLY had PsA based on my lab work but PsA is tricky. Your blood doesn't always tell the full story.