2025 – PAGE 294 – HEMATOLOGY & ONCOLOGY

COAGULOPATHY

PEARL: Platelet problems can result in bleeding or petechiae. Problems with a coagulation factor typically only result in bleeding.

VITAMIN K DEPENDENT FACTORS

The Vitamin K dependent factors include II, VII, IX and X.

MNEMONIC: 2 + 7 = 9…10

COAGULATION CASCADE

Factors XII, XI, and IX are the main INTRINSIC factors in the coagulation cascade and partially measured by aPTT. TF and factor VII are the main EXTRINSIC factors in the coagulation cascade and partially measured by the PT. Factor X is part of the common pathway.

IMAGE: www.pbrlinks.com/COAGULATION1

VITAMIN K DEFICIENCY

Although Vitamin K deficiency CAN result in a high PTT, for the boards you will likely be shown a high PT/INR and asked to identify the vitamin deficiency.

(DOUBLE TAKE) HEMOPHILIA A AND HEMOPHILIA B (AKA FACTOR VIII AND FACTOR IX DEFICIENCY)

Hemophilia A and B refer to factor VIII and factor IX deficiencies, respectively. For both hemophilias, the PTT is increased. Since this is a factor deficiency, look for deep bleeds (muscles, joints, etc.).

MNEMONIC: Have you ever encountered a female hemophiliac? Hmm. You could also imagine the X as a pair of sharp blades going through blood vessels, causing bleeding. That could remind you that hemophiliacs have an X-linked disorder.

BLEEDING CIRCUMCISION

If there is significant bleeding after a circumcision, workup the patient for a factor deficiency and consider maternal medications as a possible etiology. (Antibiotics, seizure meds, and Warfarin are some common culprits.)

VON WILLEBRAND DISEASE (AKA VON WILLEBRAND FACTOR DEFICIENCY)

Von Willebrand disease (AKA von Willebrand factor deficiency) is an autosomal dominant disorder. Both factor VIII and platelets depend on the vW factor (vWF), so there is an elevated PTT and a prolonged BLEEDING TIME. Measure VIII and IX (to rule out hemophilia) and the vWF (to confirm that it is low). Keep in mind that factor VIII can be slightly low. No treatment is needed for minor bleeding, but DDAVP can be used to increase plasma vWF and Factor VIII. For EXTREME bleeding, GIVE FACTOR VIII CONCENTRATE (AKA HUMATE-P). Cryoprecipitate can be used as a last resort (it has Fibrinogen, VIII, vWF). Aminocaproic acid is used sometimes for mucosal bleeds since it helps inhibit fibrinolysis.

DISSEMINATED INTRAVASCULAR COAGULATION (DIC)

Risk factors for disseminated intravascular coagulation (DIC) include burns, malignancy, pregnancy, and sepsis. Look for THROMBOCYTOPENIA, low fibrinogen, elevated fibrinogen split products (D-Dimer), elevated thrombin time, PT, and PTT. Treat as follows:

• Thrombocytopenia = Platelets
• Severe Anemia = PRBCs
• Low Fibrinogen = CRYOPRECIPITATE (includes Fibrinogen, factor VIII, vWF)
• Low clotting factors = FRESH FROZEN PLASMA (FFP). It has MOST of the clotting factors and is very expensive. FFP is also used to reverse Warfarin.
• FIX THE UNDERLYING CONDITION!