D-Dimer Tests: What is Their Role in Covid-19?

Different kinds of tests like antigen tests are being used to diagnose Covid-19.  RT-PCR tests, D-dimer tests but their significance varies and so do their roles. Some are being administered to detect the virus whereas tests like D-Dimer or Fragment D-dimer tests are correlated with in-hospital mortality and severity of Covid-19 pneumonia. Let’s start by understanding what a D-dimer is.

What is a D-dimer?

D-dimer is a fragment of the protein that develops when a blood clot gets dissolved in your body. It is generally not detectable and even if found, a very low quantity is detected. However, in case the body is forming and breaking down blood clots more than usual then these fragments significantly rise in the body that increases their visibility.

The D-dimer test looks for these protein fragments in the blood.

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Why Does Our Body Produce D-dimer?

When the blood vessels or tissues in our body get ruptured and the injury causes bleeding, our body starts creating blood clots to minimize and gradually stop the bloodshed. This process is called hemostasis.

During hemostasis, our body produces fibrin (protein threads) that form a net along with platelets transforming into blood clots that further act as a bandage over the injury until it gets healed.

After some time the injured patch heals and another enzyme (plasmin) breaks down the clot so that it can get dissolved in the blood, degrade, and finally get removed. Fibrin D-dimer is one of the degradation products (residual) and can only be detected if still present in the blood sample while testing.

Blood Clotting disorders

A D-dimer test is used to diagnose the following blood clotting disorders-

• Deep vein thrombosis (DVT)- Blood clots deep in the vein, generally in the lower legs.
• Pulmonary embolism (PE)-A congestion in the lungs artery that happens mostly when a blot clot breaks and gets passed on to the lungs.
• Disseminated intravascular coagulation (DIC)- Formation of multiple blood clots in the body that can cause organ damage and other related complications like cancer.
• Brain Stroke- Stroke happens when there is a blockage in the brain causing the improper flow of blood to reach the brain parts.

D-dimer and Covid-19

IFSC guidelines strongly recommend D-dimer testing for Covid-19 patients. According to studies severe Covid-19 cases were correlated with high D-dimer levels.

While most of the Covid-19 cases are mild but they can get severe and lead to treatment-resistant pyrexia, ARDS (Acute Respiratory Distress Syndrome), organ dysfunctioning, and lung injuries which are associated with a “substantial” degree of mortality.

There is the presence of micro pulmonary embolism (lodging of blood in an artery preventing blood to flow to other parts) in severe Covid-19 patients which causes respiratory failures.

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D-dimer Cut-off

A normal D-Dimer is considered less than 0.50 (also called <500). A positive D-Dimer is 0.50 or greater.

Value of more than 3 FEU μg/mL in patients was linked to 85% sensitivity and an extent for predicting if the patient can develop Deep Vein Thrombosis blood disorder or not.

The cut off value for PE (Pulmonary Embolism) prediction should be higher than what is used in non-COVID-19 patients because the D-dimer values in patients who are infected with the coronavirus are typically above what is considered normal.

Conclusion

D-dimer levels were found more in the elderly people and patients with comorbidities who required hospitalization. D-dimer levels correlation with Covid-19 severity is a biomarker for in-hospital mortality.

Though different labs have different ways of testing, if the result is found "negative," there should be no clotting issues but if your result is "high”,  you can consult a doctor on The Wellness Corner app and go for further additional tests since this test can’t exactly confirm that you have DVT or PE. If you are diagnosed with Covid-19 you can opt. COVID-19 Care Package and get yourself tested right from home to keep your health parameters in check.

Footnote: The biggest challenge then was to find a cure for the deadly coronavirus but the biggest challenge now is to unify people to get vaccinated. Don’t let the sleepless nights of our corona warriors go in vain. If you are eligible, it is best to get yourself vaccinated at the nearest center because there’s nothing more valuable than the life you are blessed with. Save the world from another mass destruction by saving yourself! #IndiaFightsCorona