I have to agree that IL-6 is key although I have never had my IL-6 level checked. My rheumatologist thinks checking my IL-6 level isn't necessary since my symptoms resolved on Actemra which is an IL-6 receptor blocker.

My CRP levels and ESR are still checked regularly. It was a good thing they were checked when my Actemra dose was being reduced. My CRP level ticked up a bit but I can't say my symptoms were any worse.

I thought CRP and ESR levels were useless. Even when I wasn't on Actemra, I can't say my CRP and ESR levels were all that useful because they fluctuated so much. They aren't specific to what is causing the inflammation.

"According to the research, clinical trials of IV tocilizumab demonstrated that maintaining serum trough tocilizumab concentrations ≥1 µg/mL resulted in a normalized CRP concentration (< 1 mg/dL). This suggests that CRP is a useful biomarker for tocilizumab levels high enough to inhibit IL-6 signaling."

My rheumatolologist says CRP is still useful to help him establish the optimal dose of Actemra for me. I don't understand any of this but I'm glad my rheumatolgist does.