D dimer test and sample collection procedure

Normally D-dimer levels are undetectable or detectable at very low levels, but they rise sharply when the body breaks down clots. D-dimer tests help in ruling out pulmonary embolisms in hospitalised Covid-19 patients

1. D-DIMER TEST Blood Sample Collection Procedure DR.ANJALATCHI ELMCH

2. DEFINITION 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 . D- dimer concentration may be determined by a  blood test  to help diagnose  thrombosis . [2]  Since its introduction in the 1990s, it has become an important test performed in people with suspected thrombotic disorders, such as  venous thromboembolism

3. WHY ITS IMPORTANCE IN COVID -19 D- dimer levels are used as a predictive  biomarker  for the blood disorder,  disseminated intravascular coagulation  and in the coagulation disorders associated with  COVID-19 infection . [1] [3]  A four-fold increase in the protein is an indicator of poor prognosis in people hospitalized with  COVID-19 .

4. ORIGIN OF D-DIMER D- dimer formation.  Shown are  fibrinogen , with its one  E  domain and two  D  domains, acted upon in cascade, by the following  enzymes :  Thrombin , to create a  mesh of fibrin   protofibrils ;  Factor XIII  to  crosslink the fibrin mesh  (linking protofibril D domains), the scaffold for  clot  formation;  Plasmin , whose action in  fibrinolysis  produces  fibrin degradation products  ( FDPs ), the smallest of which are  D- dimers , protein fragments with one E and two crosslinked D domains from an original fibrinogen .

5. D- Dimer Flow Chart

6. WHERE ITS PRESENT

7. D- dimer test A D- dimer test is  used to find out if you have a blood clotting disorder . These disorders include: Deep vein thrombosis (DVT), a blood clot that's deep inside a vein. These clots usually affect the lower legs, but they can also happen in other parts of the body. As many as 100,000 deaths occur each year in the US due to DVT and PE. 4 The symptoms you may have include: 5 Swelling or redness, usually in the lower leg but sometimes in the thigh, pelvis, or an arm Pain in the leg, thigh, pelvis, or arm Difficulty breathing Fast heartbeat Chest pain Sweating a lot

8. CAUSES OF HIGH –D-DIMER TEST

9. Other risk factors: Age : People over 60 years of age have a higher risk of blood clots. Cigarette smoking Race : African Americans have higher levels of D- dimer compared to people of European ancestry. 12 Gender : Women have higher levels of D- dimer than men. 12 Obesity Sedentary lifestyle : Not exercising or not moving for an extended period can increase the risk of DVT or PE. 5  An example is a long plane ride or being in the hospital.

10. Indications it used for? A D- dimer test is used to find out if you have a blood clotting disorder. These disorders include: Deep vein thrombosis  (DVT) , a blood clot that's deep inside a vein. These clots usually affect the lower legs, but they can also happen in other parts of the body. Pulmonary embolism  (PE) , a blockage in an artery in the lungs. It usually happens when a blood clot in another part of the body breaks loose and travels to the lungs. DVT clots are a common cause of PE. Disseminated intravascular coagulation (DIC) , a condition that causes too many blood clots to form. They can form throughout the body, causing organ damage and other serious complications. DIC may be caused by traumatic injuries or certain types of infections or cancer. Stroke , a blockage in the blood supply to the brain.

11. Medical conditions and treatments: Heart disease : Patients with unstable angina or who have had a heart attack have higher levels of D- dimer and a higher risk of future blood clots. Cancer : Some cancers can increase the risk of a blood clot. Cancer treatment : Chemotherapy and certain breast cancer drugs can increase the risk of blood clots. 8 Treatment with estrogen :  Birth control pills  and  hormone replacement therapy  can increase the risk of DVT and PE. 9 Surgery : Patients who have had major surgery, like a hip or knee replacement, have a higher risk of a blood clot. (Drugs are prescribed to prevent this.) Infectious diseases :  COVID-19  and pneumonia can cause inflammation and trigger blood clots. Kidney disease : For reasons that aren't fully understood, kidney disease increases the risk of DVT and PE. Liver cirrhosis : People with severe liver disease have a higher risk of clots in the large vein of the liver. 10 Pregnancy : D- dimer levels rise two- to four-fold by delivery. 11  Women have an increased risk of DVT or PE for up to three months after delivery. 9

12. Other Medical Conditions Coronary artery disease : People with severe heart disease have higher levels of D- dimer .  Stroke : Higher levels of D- dimer are associated with an increased risk of stroke . Disseminated intravascular coagulation (DIC) : This is a rare disease in which blood clots form in vessels throughout the body. Elevated D- dimer levels are part of the scoring test for DIC. 14 Hyperfibrinolysis : This blood clotting disorder is similar to DIC. The d- dimer test also helps doctors evaluate this disorder.

13. Criteria for D- Dimer test

14. Doctors will order other tests to make sure you don't have PE or DVT. These tests may include: Other blood tests : To see if you have a bleeding disorder Ultrasonography : A test that uses high-frequency sound waves to take pictures of your blood vessels, tissues, and organs Ventilation-perfusion lung scan : A test that uses a radioactive substance to help doctors see if air and blood can move through the lungs or if you have a blockage Computed tomography angiography : A test where you receive an infusion of a special dye. Doctors use a CT scan to take high-definition pictures from different angles. The dye lights up the blood vessels and tissues they need to check for blood clots.

15. Type of diagnostic test

16. Why do I need a D- dimer test? It may need this test if you have symptoms of a blood clotting disorder, such as deep vein thrombosis (DVT) or a pulmonary embolism (PE). Symptoms of DVT include: Leg pain or tenderness Leg swelling Redness or red streaks on the legs Symptoms of PE include: Trouble breathing Cough Chest pain Rapid heartbeat

17. during a D- dimer test? Sample collection procedure A health care professional will take a blood sample from a vein in median cubital vein in forearm , using a small needle. Quantity : 2ml After the needle is inserted, a small amount of blood will be collected into a test tube or vial . tube : blue top vial,

18. Images of tube and form

19. What do the results mean? If your results show low or normal D- dimer levels in the blood, it means you probably don't have a clotting disorder. If your results show higher than normal levels of D- dimer , it may mean you have a clotting disorder.  D- dimer Normal Range?  A D- dimer normal value is anything less than 0.50 (or <500  ng / mL FEU). A D- dimer value more than the normal range of D- dimer test is considered as a high D- dimer . Therefore, a value above 0.50 is considered an abnormal D- dimer range. However, different labs do the test in their unique ways. Thus, D  dimer normal range may differ. normal D- dimer range is 220 to 500 ng / mL.

20. RESULTS

21. Precautions Other conditions that can cause high D- dimer levels include  pregnancy ,  heart disease , and recent  surgery . If your D- dimer results were not normal, your provider will probably order more tests to make a diagnosis.

22. Is there anything else I need to know about a D- dimer test? If your D- dimer test results were not normal, your provider may order one or more imaging tests to find out if you have a clotting disorder. These include: Doppler ultrasound , a test that uses sound waves to create images of your veins. CT  angiography.  In this test, you are injected with a special dye that helps your blood vessels show up on a special type of  x-ray  machine. Ventilation-perfusion (V/Q) scan .  These are two tests that may be done separately or together. They both use small amounts of radioactive substances to help a scanning machine see how well air and blood move through your lungs.

23. Summary It may order a D- dimer test if they suspect you might have a dangerous blood clot. The test helps doctors rule out two conditions that can be fatal: deep vein thrombosis, a blood clot in a vein, and pulmonary embolism, a blood clot in the lung. A negative test result means you probably don't have a blood clot. Usually , you won't need any further tests. However, if your results come back high, that doesn't necessarily mean you have a clot.

24. https://www.ncbi.nlm.nih.gov/books/NBK431064/ https://labtestsonline.org/tests/d-dimer https://www.najms.org/article.asp?issn=1947-2714;year=2014;volume=6;issue=10;spage=491;epage=499;aulast=Pulivarthi https://medlineplus.gov/lab-tests/D-dimer-test/ https://radiopaedia.org/articles/saddle-pulmonary-embolism

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