What Causes a High SED Rate and a High C-Reactive Protein?

Both a high sedimentation rate and a high C-reactive protein are indicative of inflammation somewhere in the body, but neither test can pinpoint the source of the inflammation, state both WebMD and Lab Tests Online. Although inflammation is confirmed by a high sedimentation rate and a high C-reactive protein, more testing is necessary to determine the cause.

The sedimentation rate blood test looks at how many red blood cells fall to the bottom of a test tube in one hour, according to eMedicineHealth. The greater the number of blood cells that fall, the higher the sedimentation rate, indicating a high level of proteins being produced by the liver in response to inflammation. Because the liver produces these proteins in response to many different conditions, the sedimentation rate test is not used to diagnose a specific disease.

The C-reactive protein test measures a certain protein that is produced by the body during times of inflammation, states Lab Tests Online. It tends to rise quickly in response to inflammation, but also falls quickly when the inflammation resolves, so it is a good indicator of current conditions. Like the sedimentation rate, it only confirms inflammation without showing a source.

When the body’s immune system is triggered, specific proteins and other substances are produced, explains WebMD. When these are detected in the body, it is called inflammation. Inflammation can be a normal response to an illness, or it can be misdirected, causing autoimmune illnesses where the body is treating healthy tissue as though it is an invader.