I have seen several patients recently that simply had the wrong tests ordered by their MDs when assessing inflammation or cardiovascular risk. To prevent these testing errors, I encourage patients to better understand these tests and make sure their doctors are ordering the right ones.
A common test for inflammation is the Eosinophil Sedimentation Rate (ESR). It measures the tendency of red blood cells to clump together – rouleaux or stacking formation. This test is still offered by laboratories only because doctors not familiar with newer and superior tests still request it. ESR tests can provide inaccurate results (false positives or false negatives) for many different reasons.
C-Reactive Protein (C-RP) directly measures a liver enzyme that is an acute phase reactant. This enzymes rises quickly when inflammation is present and falls quickly when inflammation resolves. Therefore, it is an excellent marker of inflammation; better than the ESR which is more likely to be falsely positive or stay elevated after inflammation has resolved. It is the best blood test to help determine if a patient’s symptoms are due to trauma, injury, infection, auto-immune reactions, or cancer.
High Sensitivity C-Reactive Protein has many acronyms (HS-CRP, CRPHS, or Cardio C-RP). It is a test that provides an assessment of an individual’s cardiovascular risk that is independent of other measures like total cholesterol, HDL cholesterol, or homocysteine. HS-CRP measures a person’s baseline levels of inflammation and has been found to be an independent risk factor for cardiovascular disease because the formation of arterial plaques and clots that cause myocardial infarction and ischemic strokes are encouraged by chronic states of low-grade inflammation. While high sensitivity C-RP is a good measure of risk of heart attack or stroke, it is not a test to assess inflammation from trauma, injury, infection, or auto-immune disease. Frequently, this test is selected for patients when the normal C-RP is the right test. I think this happens because clinicians are assuming that the “high sensitivity” test must be better than the normal test.