0071643192.pdf

HEMATOLOGY, ONCOLOGY, ALLERGY,

AND IMMUNOLOGY

Thrombosis and hemorrhage

due to ischemia secondary to

thrombosis are the main

causes of death in patients

with polycythemia vera.

SIGNS/SYMPTOMS

■ Symptoms are generally due to sludging of blood flow leading to (ironi-

cally) poor O 2 delivery. Common complaints include weakness, headache,

vision changes, and bleeding.

■ Ruddy complexion, hypertension, pruritus are also common.

DIAGNOSIS

■ CBC, serum EPO level, splenomegaly

■ A low EPO level and elevated hemoglobin level indicate polycythemia

vera; a high EPO level suggests a secondary cause.

TREATMENT

■ Treat underlying cause, phlebotomy.

A 20-year-old female presents with complaint of easy bruising. She also re-

ports a history of heavy menstruation and prolonged bleeding after dental

extraction. Exam shows multiple areas of petechiae and purpura. Her aPTT

is increased with normal platelet count and PT. What is your suspected diagnosis?

Von Willebrand disease.

DISORDERS OF HEMOSTASIS AND CLOTTING CASCADE

Primary Hemostasis

Immediate response to vessel injury. Platelets and von Willebrand factor (vWF)

form a primary plug.

Secondary Hemostasis

■ Slower process, which activates the coagulation cascade to form a fibrin clot

■ Intrinsicpathway

■ Measure with PT.

■ Tissue factor →factor VII →factor X.

■ Extrinsicpathway

■ Measure with aPTT.

■ Factor XII →factor XI →factor IX →factor VIII →factor X.

■ Intrinsic and extrinsic coagulation pathways share a common final pathway:

■ Factor X →factor V →thrombin formation →conversion of fibrino-

gen to fibrin (see Figure 9.1).

SYMPTOMS/EXAM

■ Prolonged bleeding, easy bruising

■ Petechiae, purpura, ecchymosis

DIAGNOSIS

■ CBC, bleeding time, PT, aPTT, thrombin time, vWF activity (see Table 9.6)

Thrombocytopenia

Thrombocytopenia may result from decreased platelet production, increased

platelet destruction, or splenic sequestration (see Table 9.7).

Tissue plasminogen activator

(tPA) converts plasminogen to

plasmin, which accelerates

fibrin breakdown.