Causes of increased CRP values


CRP (C-reactive protein) is an important parameter that is usually determined when an inflammatory reaction is suspected in the body. It is a protein that is produced in the liver and acts as part of the body's own defense system by helping to recognize and fight against microorganisms and diseased cells. The determination of the CRP is used to assess and assess a suspected inflammatory reaction. However, the value must always be assessed in conjunction with other findings. In addition, the value can be increased even without relevant inflammation and, on the other hand, a non-increased CRP value does not rule out a severe infection - possibly beginning.

Here is the main article: Inflammation levels in the blood - what do elevated levels indicate?

Acute causes

If there is an acute inflammatory reaction in a person, the immune system reacts by releasing various antibodies such as CRP. Therefore, an increased CRP value can also be recorded in the blood test (usually with a delay of hours to days after the start of the inflammatory reaction). Another typical acute cause for increased CRP values ​​is, for example, major operations. These represent a burden for the body and also lead to an activation of the immune system and thus usually also to a significant increase in the CRP value.

Chronic causes

If the immune system is constantly activated, this can be the chronic cause of elevated CRP levels. For example, a non-healing wound, such as a wound healing disorder after an operation, can cause the body to release CRP while defending itself against microorganisms, and an increased concentration in the blood can be measured. Other infections such as the urinary bladder or the respiratory tract can also be a chronic cause of elevated CRP values ​​if these are not cured. However, it also happens that chronically elevated CRP levels are measured in the absence of inflammation. For example, tobacco consumption can lead to an increase in the value above the normal range. People who suffer from a chronic disease of the intestines or joints (rheumatism), for example, also often have elevated CRP values.


Elevated CRP values ​​are often measured in people who suffer from rheumatism or chronic inflammation of the joints. However, the determination of the CRP value does not serve to diagnose a rheumatic disease, so that an increased measured value alone does not indicate the presence of rheumatism. There are clearly defined criteria that must be met in order to be able to make the diagnosis. Depending on its level, the CRP value can then be used to assess the severity of an inflammatory reaction. In addition, in the course of rheumatism, an increase in the CRP value can indicate an acute flare-up. If an initially elevated CRP value drops again in the course of a person with rheumatism, this can be confirmation of the effectiveness of the therapy that has been initiated.

Read here: How do you recognize rheumatism?

Tumor / cancer

Increased CRP values ​​are also caused by malignant tumors or cancer. However, cancer is only a fraction of the cause of elevated CRP levels. It is primarily a level that increases with inflammation. An elevated CRP value alone therefore does not justify the suspicion that cancer is present. The doctor will investigate the cause of the increased CRP value based on his examination and, if necessary, further diagnostics. Even if this is initially unclear, it is not necessary to immediately think of a tumor as the cause. However, if, in addition to an increased CRP value, there are symptoms that could indicate the presence of a tumor, it makes sense to clarify this. This includes, for example, pronounced unwanted weight loss or if there is blood in the stool.

Here is the main article: CRP value in cancer


Initially, elevated CRP values ​​are not a typical finding in the blood disease leukemia. In people who suffer from leukemia, the immune system is often weakened, so that an increase in CRP often does not occur. On the other hand, an increased or rising CRP value in the presence of leukemia can indicate that there is an inflammation. Due to the restricted immune defense, people with leukemia are often more at risk from infections than otherwise healthy people. An increased CRP value in leukemia sufferers should therefore be taken seriously and, if necessary, further clarified.

Find out here: How do you recognize leukemia?


In some cases, a cold can be the cause of increased CRP levels. An infection of the upper respiratory tract caused by viruses is responsible for a cold. There are two main reasons why a cold usually leads to a slight increase in the CRP value. On the one hand, only the mucous membranes of the upper respiratory tract are affected by a slight inflammatory reaction in the case of a cold, which is only a comparatively minor burden for the body and the immune system. As a result, little CRP is usually produced. The second reason why the CRP value often does not or only slightly increases with a cold is that the disease is triggered by viruses. Viral infections generally lead to a less pronounced increase in CRP values ​​than, for example, bacterial ones. However, if a strongly increased CRP value is measured with a cold, this can indicate that there is also a serious infection. For example, one cause can be pneumonia caused by bacteria, which may then require treatment with an antibiotic.

Do you have a cold? Here it goes to: Cold - what to do

Viral infection

Even with a virus infection, increased CRP values ​​can often be measured. However, it has been proven that the CRP increases, especially when there is an inflammatory reaction caused by bacteria. Viral infections, on the other hand, often only cause moderate to slight increases. In some cases, the CRP is even normal with a viral infection. This does not mean that viral infections are generally more harmless than infections caused by bacteria. There is only usually a smaller increase in CRP values.


The flu can be the cause of high CRP levels. However, the flu is a virus-induced illness, which generally leads to a rather small increase in the CRP measured in the blood. Therefore, even with severe flu with pronounced symptoms, it often happens that the CRP value is only slightly or not at all. If severely elevated CRP values ​​can be measured when flu symptoms are present, this may be an indication that it is not the flu but possibly pneumonia caused by bacteria. In some cases, elderly people with the flu can develop what is known as a bacterial superinfection, which then requires treatment with an antibiotic. In addition to a worsening of the condition, an increase in the CRP value can indicate such a course.

Read more about this: Flu complications


A tonsillitis is one of the common possible causes of high CRP levels. The tonsils are organs of the immune system. In the case of inflammation, usually caused by bacteria, a chain of reactions ultimately leads to an increased production and release of CRP in the liver. The level of the CRP value often correlates with the severity of the inflammation. If the tonsillitis heals, the CRP value usually drops again. Chronic or recurring tonsillitis can also be responsible for constantly high CRP levels.


Pregnancy can be a cause of increased CRP levels. Slightly to moderately elevated values ​​can be measured in many women who are pregnant and can then be regarded as normal. Only strongly increased or rising CRP values ​​in connection with symptoms such as fever or pain should also be considered during pregnancy and further clarified if necessary.In many cases, however, an increased CRP value during pregnancy cannot be used, so that its determination is often not effective.

After surgery

An operation leads to a strong stress reaction in the body and thus to an activation of the immune system. It is therefore to be expected that increased CRP values ​​can be measured after an operation. With a normal course without complications, the value drops again after a few days. In the first few days after an operation, elevated CRP values ​​can therefore be regarded as normal. The expected increase also depends on the extent and duration of the operation. If the CRP does not decrease or even increase in the course of the operation, this can be an indication for the doctors that a complication is looming, such as a wound healing disorder or pneumonia. However, the CRP value must always be viewed in conjunction with the patient's complaints and possible findings such as fever or pain.

lung infection

Pneumonia typically leads to increased CRP levels. In order to diagnose pneumonia, however, the typical symptoms such as fever, newly emerging shortness of breath and coughing must occur. In addition, any new shading must be proven via an X-ray image. An elevated CRP value is only of secondary importance when making a diagnosis of pneumonia. Conversely, non-elevated values ​​make pneumonia very unlikely, so that in such a case an X-ray can often be dispensed with. However, the CRP values ​​become more important after initiation of therapy. If this does not decrease after a few days after the initiation of antibiotic treatment or even continues to increase, this indicates that the therapy is not working and that it should be switched to another drug if necessary.

Find out more about the here Signs of pneumonia

Blood poisoning

In the case of blood poisoning, which is also known medically as sepsis, there is a pronounced reaction of the body's own defense system and thus, among other things, a pronounced release of inflammatory agents. Blood poisoning therefore usually leads to greatly increased CRP values. Conversely, if there is an inflammation that leads to a significant increase in CRP levels, the onset of sepsis should be considered. After initiating therapy for sepsis, the determination of the CRP values ​​can be used as a parameter for a response to the therapy. Furthermore, greatly increased CRP values ​​can indicate an inadequate response of the body to the treatment. In the case of blood poisoning, the so-called procalcitonin is often determined in addition to the CRP.

You can find them here Symptoms of blood poisoning


In the case of elevated CRP values, HIV infection should not be considered as the cause. HIV is a virus that attacks the defense cells of the immune system and destroys them gradually, usually over a period of years. If you are infected with HIV for the first time, increased CRP values ​​are possible, but these are of little significance. For one, they are non-specific, which means there are many other possible causes for the increase. On the other hand, increased CRP values ​​are not sensitive to the question of whether an HIV infection is present. This means that you can become infected with HIV without increasing HIV levels. It only makes more sense to contact a doctor immediately if there is a justified suspicion of an infection, for example after having sex with an HIV-positive person.

Back pain

If increased CRP values ​​occur in connection with back pain, various causes are possible. Often the two findings are not related, that is, one suffers from back pain and the increased CRP value has a completely different cause. However, constellations are conceivable in which the back pain and increased CRP values ​​can be traced back to a common trigger. In the case of pain in the flanks, if the CRP values ​​are elevated, for example, an inflammation of the kidneys should be considered, especially in the case of unilateral pain and fever. However, the assessment of whether there is a connection between back pain and elevated CRP values ​​can only be made by the doctor after his examination.

You can find effective ones here Exercises for back pain

Urinary tract infection

Urinary tract infections are among the most common infections in humans and are therefore also the cause of a large number of elevated CRP values. A urinary tract infection can be suspected as the cause of increased CRP values, particularly when typical symptoms such as burning sensation when urinating and pain in the abdomen occur. Urinary tract infections restricted to the bladder often only lead to a slight increase in CRP values ​​(up to 10 times the norm). However, if the inflammation increases to the kidneys, the CRP can also increase sharply over time. Typical signs are flank pain and fever. The worst form of urinary tract infection, so-called urosepsis, can also lead to extremely high CRP values ​​(up to 100 times the norm).


Osteomyelitis is an inflammation of the inside of the bones and this usually also leads to increased CRP values. In general, however, osteomyelitis is only responsible for a very small proportion of increased CRP values. This clinical picture should be considered if there are suspicious findings. A pronounced and deep wound infection on the foot in diabetics can serve as an example.

Crohn's disease / ulcerative colitis

Crohn's disease and ulcerative colitis are so-called chronic inflammatory bowel diseases which, among other things, can lead to increased CRP values. If there are typical findings of such a disease such as frequent diarrhea over a long period of time, a colonoscopy should be performed if necessary. Ultimately, it is only possible to determine whether Crohn's disease or ulcerative colitis is present by examining samples from the intestinal mucosa using the tissue. A colonoscopy is required to obtain them. In people with a proven chronic inflammatory bowel disease, an elevated CRP value suggests increased activity of the disease. The evaluation of the laboratory parameter must always be made in connection with other findings such as general well-being, stool frequency and pain.


Diverticulitis is one of the most common causes of elevated CRP levels. In western countries in particular, bacterial inflammation of bulges in the large intestine is a common disease. Elevated CRP values ​​together with symptoms such as pain in the (typically left) lower abdomen and possibly fever should therefore suggest the presence of diverticulitis as the cause. Slight inflammations usually lead to only slightly increased CRP values. If, on the other hand, a particularly high value is measured, this can indicate particularly pronounced diverticulitis. In the case of corresponding symptoms, an emergency diagnosis in the hospital may even be necessary in order to rule out, for example, an intestinal rupture or peritonitis or at least detect it in good time.

Here you can find out more about proper nutrition for diverticulitis.