Coagulation Disorders in COVID-19 patients

Blood clotting (coagulation)

Blood clotting, or coagulation, is an important process that prevents excessive bleeding when a blood vessel is injured. Platelets (a type of blood cell) and proteins in your plasma (the liquid part of blood) work together to stop the bleeding by forming a clot over the injury. Typically, your body will naturally dissolve the blood clot after the injury has healed.

In pathological conditions, excessive accumulation of platelets and fibrin on the inside of the blood vessel may occur. This leads to a disturbance in the blood circulation until it stops due to clogging of the blood vessel with a thrombus. This condition is called thrombosis. These clots can occur anywhere – from the smallest to the largest blood vessels and cause varying degrees of damage and even death.

There is a system in the human body opposite to the coagulation, it is an anticoagulation mechanism. A constant balance is maintained between the coagulation and anticoagulation systems in the body. Thus, the organism is protected from two extreme dangers from the disturbed blood circulation – bleeding and thrombosis.

Risk factors

There are certain conditions that increase the risk of thrombosis, such as: changes in the walls of blood vessels, cardiovascular disease, rheumatic diseases, inflammation, malignancies, trauma, childbirth, taking certain medications, genetic factors and other conditions.


Depending on the clinical findings and the severity of the disease, treatment is performed at home or in hospital, only after examination and recommendation by a specialist

COVID-19 and the coagulation system

Although it is not uncommon for infections to increase the risk of clots, COVID-19 is associated with a very wide range of blood clotting disorders in diseased patients. Patients with COVID-19 experience severe and sometimes fatal blood clotting abnormalities.

Studies show that about 25% – or even up to 70% – of critically ill patients have confirmed venous thromboembolism or pulmonary embolism.

Therefore, it is crucial during the routine laboratory assessment to measure the parameters of the blood coagulation system, such as: blood count (platelet count), D-dimer, PT-Prothrombin time, aPTT- Activated partial thromboplastin time and more.


D-dimer (or D dimer) is a fibrin degradation product (or FDP), a small protein fragment present in the blood after a blood clot is degraded by fibrinolysis. It is so named because it contains two D fragments of the fibrin protein joined by a cross-link. Detection of elevated levels are a sign that the coagulation system is activated.

Normal levels of D-dimers in healthy adults are 0.5 mg / L.

Elevated levels of D-dimers in patients with COVID-19 are usually a sign that there is a risk of blood clots forming, which can spread with the circulation and cause a blood vessel to clog. Therefore, after an examination by a specialist doctor, appropriate therapy should be given and this condition should be treated.

It is very important to note that different laboratories may use different instruments, technologies, reference values and tests to determine D-dimers and therefore the results of different laboratories should not be compared.