April 2009

UPDATE ON CRP AND hsCRP

C-reactive protein (CRP) and high-sensitivity C-reactive protein (hsCRP) measure the same plasma protein which was first described as an acute phase reactant, a marker that is elevated in many infectious or inflammatory conditions. In recent years, many epidemiologic studies have established the fact that individuals with higher baseline levels of CRP are at increased risk for coronary heart disease and stroke. We offer these assays separately because they should be ordered in different clinical settings and we therefore report the results with different reference ranges that reflect the clinical setting under consideration.

Up until now, we have reported the results for these two assays in different units (i.e., mg/L for hsCRP and mg/dL for CRP). As of April 20, 2009, we will be reporting both assays in the same unit, mg/L. This is the general trend in the laboratory field, and may eliminate some confusion, since there will now be a more marked difference in the numerical values of these two assays. Because of the change in units for CRP, numerical values will be 10 X greater, as will the reference range.

As a reminder, the CDC and AHA recommend the following for the use of hsCRP:

1. The average of 2 measurements, fasting or non-fasting, optimally drawn 2 weeks apart, provides a better estimate of risk than a single value, because there can be marked biologic variation.
2. If a level > 10 mg/L is obtained, there should be a search for an obvious cause of infection or inflammation.
3. Decision intervals are < 1 mg/L, low risk; 1 to 3 mg/L, intermediate risk; > 3 mg/L high risk. These values will be listed as the reference range when you order hsCRP.
4. Universal hsCRP screening of the adult population is not recommended.
5. Patients most likely to benefit from hsCRP screening are those in whom the risk estimate from established factors is moderate, and the physician desires additional information to guide preventive therapy.

If you have any question about CRP or hsCRP, please give us a call at 269-969-6161:

            Ken Vanden Bosch at x 6932

            Dr. Jim Niewenhuis at x 6918