Fibrin degradation products (FDPs) are the substances left behind when clots dissolve in the blood. This article discusses the blood test to measure these products.

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

The blood is sent to a laboratory. The laboratory specialist will run tests on the blood sample to measure the products that are left behind when blood clots dissolve.

Your health care provider may tell you to stop taking certain drugs before the test. Drugs that may increase FDPs include barbiturates, heparin, streptokinase, and urokinase.

Do not stop taking any medicine without first talking to your doctor.

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

This test is done to see if your clot-dissolving (fibrinolytic) system is working properly. Your doctor may order this test if you have signs of disseminated intravascular coagulation (DIC) or another clot-dissolving disorder.

The result is normally less than 10 micrograms per milliliter (mcg/mL).

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

Increased FDPs may be a sign of primary or secondary fibrinolysis (clot-dissolving activity) due to:

• Abruptio placentae
• Burns
• Congenital heart disease
• Disseminated intravascular coagulation (DIC)
• Hypoxia
• Infections
• Intrauterine fetal death
• Leukemia
• Liver disease (See: cirrhosis)
• Portacaval shunt
• Preeclampsia
• Recent blood transfusion
• Recent surgery that involved a heart and lung bypass pump
• Renal disease (See: kidney failure)
• Septicemia
• Thromboembolic states
• Transplant rejection
• Transfusion reaction

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Schafer AI. Hemorrhagic disorders: Disseminated intravascular coagulation, liver failure, and vitamin K deficiency. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 181.