C-reactive protein (CRP) is a protein the liver makes, and levels increase if there is inflammation in the body.
Doctors measure CRP levels through a blood test to check for septic arthritis. A CRP level of more than 2 mg/dL is a strong risk factor for septic arthritis.
Researchers have found that elevated CRP levels are the strongest predictor of septic arthritis of the hip. Elevated CRP levels, in combination with an inability to bear weight, are strong predictors for septic arthritis of the knee.