D-Dimer, CRP and IL6 Inflammatory Markers for COVID19
D-Dimer, CRP, and IL6 Inflammatory Markers and their significance for COVID 19 is a subject of high importance today. Though all these inflammatory markers existed for a long and have been serving as an indicative factor in many diseases. But during this Pandemic, these biomarkers have become significant factors to correlate the severity of COVID 19 in patients. Let us understand each of these markers briefly and also know why are they important.
The first thing to know is that all these are not directly related to COVID. These markers exist for a long and indicate inflammation and infection in the body. The inflammation can happen due to COVID or may happen due to various other diseases, like normal viral fever, bacterial infection, Tuberculosis, arthritis, etc.
D-Dimer test is a test to find out the possibility of a blood clot in the human body. This test measures the amount of a protein called “fibrin D-dimer” in the blood. Fibrin is the chief component of a blood clot. Blood clotting is a complex process when it happens the blood changes from liquid to a semi-solid gel-like clump. The clotting otherwise is necessary to prevent losing out so much blood in case of injury or cut. But when this happens inside the vein and doesn’t dissolve on its own then it is a life-threatening situation.
D-dimers have been discovered as by-products of fibrinolysis, the enzymatic breakdown of the fibrin in blood clots. The level of D-dimer in the blood may rise in case of the breakdown of fibrin clots in the body.
It reflects ongoing activation of the hemostatic system. The following table reflects the reference range of D-Dimer
|First trimester||Second trimester||Third trimester|
|mg/L or µg/mL||< 0.5||0.05 – 0.95||0.32 – 1.29||0.13 -1.7|
|µg/L or ng/mL||< 500||50 – 950||320 – 1290||130 – 1700|
|nmol/L||< 2.7||0.3 – 5.2||1.8 – 7.1||0.7 – 9.3|
This test is important for COVID patients to rule out any blood clots due to invasion of SARS-CoV-2.
CRP or C reactive Protein
Your doctor may advise you to get your CRP levels checked in case you are infected with COVID19. CRP is produced in the liver and can be checked through a blood test. Elevated levels of CRP will indicate inflammation in the body. Patients with mild to severe levels of COVID infection have been seen with elevated levels of CRP in them. For example, a study reported that patients with more severe symptoms had on average CRP concentration of 39.4 mg/L and patients with mild symptoms CRP concentration of 18.8 mg/L. The patients who died from COVID‐19 had about 10 fold higher levels of CRP than the recovered patients.
IL6 or Interlukin6 Test
This test is used as a predictor for the severity of disease in Covid-19. ROC analyses identified IL-6 as the most robust predictor of hypoxemia. Patients with oxygen saturation level below 90% had a significantly higher concentration of IL-6 >24 pg/ml