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What Is the Difference between an ESR and CRP Test?

ESR and CRP tests both measure inflammation in the body, but they differ in sensitivity and response time. ESR indicates the rate at which red blood cells settle, reflecting inflammation indirectly, while CRP levels rise rapidly in direct response to inflammation, offering a more immediate picture. Intrigued by how these tests inform medical decisions? Let's examine their unique roles in healthcare.
Toni Henthorn
Toni Henthorn

The erythrocyte sedimentation rate (ESR) test and the C-reactive protein (CRP) test are laboratory blood tests that healthcare professionals use to detect and monitor inflammation in the body. Both ESR and CRP are increased in the presence of acute inflammatory conditions, such as rheumatoid arthritis, polymyalgia rheumatica, inflammatory bowel disease, and other autoimmune conditions. The ESR measures the rate at which red blood cells separate from the fluid component of blood, the serum, with an increased rate of separation indicative of increased blood protein levels of fibrinogen, immunoglobulins, and other chemical agents that are present in inflammatory states. On the other hand, CRP measures the level of C-reactive protein, a substance that is generated by the liver in infectious or inflammatory situations. As a result, while both may indicate inflammation, ESR is an indirect sign of the condition and CRP is a direct indicator of it.

These tests are also useful to monitor the activity of autoimmune diseases and the patient's response to any medications that physicians prescribe to treat the condition. Changes in ESR are slower than changes in CRP, so it is a less sensitive indicator. In addition, many non-inflammatory conditions may elevate the ESR, such as anemia, menstruation, pregnancy, and use of a variety of medications. While both tests are readily available commercially, the ESR test is easier and less expensive than CRP.

ESR measures the rate at which the red blood cells separate in the blood.
ESR measures the rate at which the red blood cells separate in the blood.

Healthcare professionals obtain both ESR and CRP levels by drawing blood from a peripheral vein. When heart disease is suspected in an apparently healthy person, a medical professional may order high-sensitivity C-reactive protein (hs-CRP) test to evaluate the potential risk for cardiac injury. The hs-CRP detects extremely small quantities of C-reactive protein in the blood stream in the range of 0.5 to 10 milligrams per liter of blood (0.00007 ounce per gallon), providing the high degree of sensitivity required to identify accurately an initial or proceeding heart attack. Neither ESR nor CRP tests are sensitive enough for cardiovascular disease applications.

Doctors can get ESR and CRP levels by drawing blood.
Doctors can get ESR and CRP levels by drawing blood.

Recent studies indicate that ESR tests may play a beneficial role in screening elderly patients for occult disease. A radical increase of the ESR strongly suggests a problem, most often an autoimmune disease, infection, or even a spreading cancer. Many patients with an ESR level exceeding 100 have myeloma, a condition in which certain white blood cells proliferate excessively and destroy body organs. As a result, a high level in an elderly patient may require further testing, such as additional blood and urine tests, chest X-rays, and liver function tests.

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Discussion Comments

Rundocuri

@ocelot60- While both of these diagnostic blood tests should be covered by health insurance when recommended by a doctor, every health insurance policy has different criteria when it comes to coverage. Deductibles and co-payments also play roles in how much a patient will owe after the coverage kicks in.

You friend's best bet is to call her health insurance company and ask about her coverage so she will have a good idea what amount she might have to pay for her ESR and CRP tests.

Ocelot60

Does anyone have any thoughts about whether or not ESR and CRP tests are covered by health insurance plans? I have a friend who needs to have several blood tests and is concerned about her insurance coverage for them.

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    • ESR measures the rate at which the red blood cells separate in the blood.
      By: Alexander Gospodinov
      ESR measures the rate at which the red blood cells separate in the blood.
    • Doctors can get ESR and CRP levels by drawing blood.
      By: inkaone
      Doctors can get ESR and CRP levels by drawing blood.
    • Menstruation can elevate ESR levels.
      By: matka_Wariatka
      Menstruation can elevate ESR levels.
    • Both ESR and CRP levels may be increased due to rheumatoid arthritis.
      By: designua
      Both ESR and CRP levels may be increased due to rheumatoid arthritis.
    • CRP measures the level of C-reactive protein that the liver produces during an infection.
      By: pankajstock123
      CRP measures the level of C-reactive protein that the liver produces during an infection.