CRP blood test
CRP (C-Reactive Protein) blood test measures the levels of a special protein produced by the liver during infection or acute inflammation. Usually blood does not contain CRP. CRP blood tests are often done to diagnose rheumatic fever, cancer, tuberculosis, pneumonia or heart attack. Often CRP test is suggested along with ESR blood test to check for rheumatoid arthritis and lupus. Pregnant women or women on oral contraceptives may notice positive CRP in the blood. Since CRP blood test is indicative of inflammation in the blood, it is an important predictor of heart problems.
This blood test aids in detecting the risk of developing myocardial infarction. In patients suffering acute coronary syndrome, the hsCRP test can predict the risk of developing cardiovascular disease or ischemia. The reference range for hsCRP:
Low Risk: < 1 mg/L
Average Risk: 1 - 3 mg/L
High Risk: >3 mg/L
Acute inflammation: >10 mg/L
ESR blood test
ESR (erythrocyte sedimentation rate) blood test is used to measure the distance that RBCs settle in unclotted blood. Blood sample is monitored for an hour in a specially-marked test tube. The levels of ESR indicate any inflammatory or malignant disease. This test is often used to diagnose rheumatologic ailments, tuberculosis or tissue necrosis. Elevated levels of blood ESR may be indicative of rheumatoid arthritis, thyroid disease, kidney disease, syphilis or tuberculosis. Pregnancy, infection and old age can bring about elevated levels of blood ESR. Extremely low levels of ESR may suggest sickle cell anemia, Hypofibrinogenemia (Fibrinogen deficiency), CHF or hyperviscosity. ESR is a non-specific inflammation marker and may need to be supported with other diagnostic tests for medical decisions. ESR blood test is often suggested along with CRP blood test to check for arthritis since they both check for proteins associated with inflammation. However, a normal value of ESR does not rule out disease.
ESR is also known as Acute Phase Reactant Test as it reacts to severe conditions - infections or trauma. The Erythrocyte Sedimentation rate increases, some times directly in relation to a rise in body temperature and increase in white blood cell count. ESR reaches a peak after many days and usually it lasts longer than high temperature or increased white blood cell count.
Many diseases induce the body to make abnormal proteins that cause the red blood cells to clump together and stack up which results in a column called as Rouleaux. In such a situation as the red cells are heavier, they fall faster and settle further resulting in higher ESR.
ESR Results - Normal values (Westergren method):
The highest ESR levels are usually seen in a cancer involving white blood cells - Multiple Myeloma and Rheumatoid disease. Other diseases which elevate the ESR : infections, anemia, kidney disease, inflammatory conditions, white blood cell disorders, cancer and autoimmune diseases.
Any disease or condition which affects the shape and size of RBC decreases the ESR. Diseases that cause the body to make less protein or extra red blood cells will also decrease the ESR. Some medicines such as anticonvulsant, and oral contraceptives may increase the ESR while drugs like Cortisone and Quinine may decrease the ESR.
Bibliography / Reference
Collection of Pages - Last revised Date: January 16, 2019