Chronic inflammation can result from a viral or microbial infection, environmental antigen, autoimmune reaction or persistent activation of inflammatory molecules.
"Unlike acute inflammation, chronic inflammation is abnormal and does not benefit the body," explained Victoria J. Drake, PhD, manager of the micronutrient information center at Oregon State University's Linus Pauling Institute. "In fact, chronic inflammation is involved in a number of disease states.
Several human diseases are inflammatory in nature, including asthma, Crohn's disease, rheumatoid arthritis, polymyalgia rheumatica, tendonitis, bursitis, laryngitis, gingivitis, gastritis, otitis, celiac disease, diverticuliti and inflammatory bowel disease. Additionally, a number of chronic diseases have inflammatory components, such as atherosclerosis, obesity, diabetes mellitus, cancer and even some neurodegenerative diseases like Alzheimer's disease, Drake told ADVANCE.
Biomarkers of Chronic Inflammation
Several different laboratory tests can be used to identify inflammation in the body. The main clinical assays used, according to Drake, are a high C-reactive protein (CRP) level, high erythrocyte sedimentation rate (ESR), high white blood cell count or low albumin level. Other assays, such as measuring cytokine or adhesion molecule levels, are used in biological research, she explained.
CRP, a protein that can be measured in the blood, is a critical inflammatory marker. This protein appears in higher amounts when there is inflammation somewhere in the patient's body. CRP levels can be checked with a simple blood test. According to some researchers, people who have been treated for high C-reactive protein levels are less likely to have a heart attack or stroke.
ESR, or sed rate, is a test that indirectly measures how much inflammation is in the body. The test measures how fast red blood cells called erythrocytes fall to the bottom of a tall, thin tube, according to experts with the National Institutes of Health (NIH).
Because it's a screening test, the EST test can be used to monitor inflammatory diseases and cancer but cannot be used to diagnose a specific disorder. The test measures the rate at which red blood cells sediment by millimeter in a period of one hour. According to the NIH, test results that fall in the normal range measure less than 15 mm/hr for men under 50 years old; less than 20 mm/hr for men over 50 years old; less than 20 mm/hr for women under 50 years old; and less than 30 mm/hr for women over 50 years old.
Also called leukocytes, white blood cells (WBCs) help fight infections. The body produces more white blood cells when the patient has an infection or allergic reaction. The normal range, as defined by the NIH, is 4,500 to 10,000 white blood cells per microliter. A high number of WBCs may indicate chronic inflammation.
A serum albumin test measures the amount of albumin, protein made by the liver, in the clear liquid portion of a patient's blood. A blood sample is taken through venipuncture.
According to the NIH, albumin helps move small molecules such as bilirubin, calcium and progesterone through the blood and helps prevent fluid from the blood from leaking out into the tissues.
Normal levels of albumin, as reported by the NIH, fall into the range of 3.4 to 5.4 grams per deciliter (g/dL). Low albumin levels can be an indication of numerous conditions and disorders. Low albumin levels can be seen in inflammation and malnutrition or with conditions in which the body does not properly absorb and digest protein, such as Crohn's disease.
"Several tests, however, are nonspecific meaning an abnormal result might indicate presence of a condition unrelated to inflammation," said Drake.
Rebecca Mayer Knutsen is on staff at ADVANCE.