Chronic inflammation is low-grade inflammation that lasts for many months to years. It is an underlying factor driving many chronic diseases that plague modern society, including heart disease, diabetes, and cancer. The good news is that there are specific tests your doctor can order to tell if you’re suffering from chronic inflammation. There are also tests that your doctor may order for other purposes that can inadvertently reveal chronic inflammation. Read on to learn more about these tests and discover the main causes of chronic inflammation.
What is Chronic Inflammation?
Inflammation is the body’s natural response to heal tissue that is damaged or infected with bacteria, viruses, or fungi. It’s a healthy process when it’s kept in check. But it can be unhealthy when it goes on for too long.
There are two types of inflammation: acute and chronic. Acute inflammation is short-term inflammation that begins rapidly and only lasts for days or weeks. It’s usually caused by trauma, infection, or toxic substances. Signs of acute inflammation include [1]:
- Redness
- Heat
- Swelling
- Pain
- Loss of function
If acute inflammation is not resolved, it can turn into chronic inflammation: low-level, long-term inflammation that lasts for months to years. Symptoms of chronic inflammation include [2]:
- Pain
- Fatigue and insomnia
- Depression, anxiety and mood disorders
- Constipation, diarrhea, and acid reflux
- Weight gain
Research shows chronic inflammation plays a key role in most major chronic diseases including [2, 3]:
- Heart disease
- Diabetes
- Autoimmune diseases
- Arthritis
- Allergies
- Alzheimer’s disease
- Inflammatory bowel disease (IBD)
- Cancer
Infections, an unhealthy diet, and obesity can all cause low-grade, chronic inflammation [2].
5 Blood Tests That Reveal Chronic Inflammation
1) High-sensitivity C-reactive Protein (hs-CRP)
C-reactive protein (CRP) is a protein that increases when there are inflammation and infection in the body. It’s made in the liver in response to inflammatory molecules called cytokines. CRP binds to damaged tissue or microbes and tags them so the immune system can clear them away [4, 5].
Highly-sensitive CRP (hs-CRP) is a test that is able to measure CRP levels below < 10 mg/L, which a regular CRP test is unable to do. This makes it a great test to determine if you have any systemic, low-grade inflammation [6].
2) IL-6
Cytokines are small proteins that help immune cells “talk” to each other. They help the body coordinate an immune response to infection and trauma. Interleukin-6 (IL-6) is a cytokine that has both pro- and anti-inflammatory properties. It is important for immune system function and deficiencies can lead to increased susceptibility to infections [7, 8].
IL-6 also stimulates the breakdown of bones and helps to reduce inflammation caused by exercise [9].
IL-6 plays a key role in the transition from acute to chronic inflammation. It also causes the release of CRP from liver cells, furthering the cycle of inflammation [10].
The IL-6 test is not frequently ordered. CRP is the most commonly ordered test to check for inflammation. However, your doctor may order IL-6 in conjunction with or following a CRP test if you have a condition associated with inflammation, such as lupus or rheumatoid arthritis, or an infection, such as sepsis.
Your doctor can also use this test to evaluate your risk of diabetes, stroke, or heart disease.
3) Ferritin
Ferritin is an iron-storing protein. It is important for maintaining proper iron levels and making sure that iron is available for the body to use. Ferritin is a measure of how much iron is in the body and is often tested to determine if someone has an iron deficiency.
Iron is needed to make red blood cells, and also helps produce energy. However, when there is an infection, ferritin levels will often rise to prevent pathogens such as bacteria, viruses, fungi, etc. from using iron [11, 12].
When cells are damaged, ferritin can leak out into the bloodstream, causing levels to rise. Ferritin levels are also closely correlated with CRP and are elevated in many chronic inflammatory diseases including non-alcoholic liver disease (NAFLD), obesity, and many types of cancer [13, 14, 15, 16].
Your doctor will order ferritin to check for iron deficiency or overload. High levels without iron overload may inadvertently point to chronic inflammation.
4) Fibrinogen
Fibrinogen is a protein in the blood that is activated by the enzyme thrombin to help form clots in the blood. It is important for new blood vessel development and healing damaged tissue [17].
Like CRP, fibrinogen is a protein that increases in response to inflammation (acute-phase reactant). Fibrinogen and its byproducts are also able to activate many different immune cells [17].
Fibrinogen is increased during chronic infections such as gum disease and plays a key role in many inflammatory diseases such as rheumatoid arthritis, ulcerative colitis, and many types of cancer [18, 17].
Your doctor may order a fibrinogen test to help diagnose or exclude bleeding or blood clotting issues. In some cases, fibrinogen can also be tested when your healthcare practitioner wants to have additional information to help evaluate your risk of heart disease. A high level is not used to check for chronic inflammation, but can point to it nonetheless.
5) Tumor Necrosis Factor Alpha (TNF-α)
TNF-α is a pro-inflammatory cytokine, meaning it stimulates the immune response [19].
TNF-α is one of the earliest responders in the immune response and is rapidly released after infection, trauma, or exposure to bacterial toxins (lipopolysaccharides, or LPS). In the process of destroying microbes, TNF-α can also cause damage to nearby cells [20].
TNF-α levels are commonly elevated and play a key role in many inflammatory disorders, including diabetes and heart disease [21].
TNF-α test is currently being developed. It is available from certain labs, but is currently used only for research purposes. There are not enough studies to establish valid ranges or health effects associated with those ranges.
Causes of Chronic Inflammation
Causes below have been associated with chronic inflammation. Work with your doctor to get an accurate diagnosis and to resolve any underlying health issues.
1) Lingering Infections
If the immune system fails to get rid of an infection (fungal, bacterial, parasitic, etc.) during the acute inflammation phase, the infection continues to cause low-level chronic inflammation [2].
For example, persistent infection of the gum tissue (periodontal disease) can lead to systemic chronic inflammation and elevated CRP and fibrinogen levels [18].
2) Environmental Toxins
Heavy metals like arsenic, lead, and mercury can accumulate in the body, causing tissue damage and chronic, low-level inflammation [22, 23].
Pesticides and air pollution are strongly linked to chronic inflammatory conditions like asthma and allergies [24].
Cigarette smoke is another toxic substance that causes inflammation in the mucous membranes of the lungs, throat, sinuses, and mouth [25].
3) Diet
Studies suggest that modern diets high in omega-6 relative to omega-3 fats cause low-grade, chronic inflammation [26].
Eating foods with trans-fats, commonly found in cakes, cookies, potato chips, and popcorn, has been associated with increased levels of CRP and IL-6 [27].
Diets high in refined starches and sugars spike blood sugar levels and increase IL-6 and TNF-α levels [28, 29].
4) Inactive Lifestyle
Exercise is a powerful anti-inflammatory factor. An inactive lifestyle is associated with increased CRP and IL-6 levels and studies suggest that replacing sedentary time with moderate or vigorous exercise can help decrease these inflammatory molecules [30, 31, 32].
5) Obesity and Excess Body Fat
Fat tissue is now considered to be an organ that releases inflammatory molecules such as TNF-α and IL-6. Obesity and excess body fat are associated with higher levels of CRP, TNF-α, and IL-6 and studies have shown that weight loss reduces these markers [33, 34, 35, 36, 37].
6) Stress
Stress increases IL-6 and CRP levels and research suggests that chronic stress can keep these markers persistently elevated [38].
