0071643192.pdf

HEMATOLOGY, ONCOLOGY, ALLERGY,

AND IMMUNOLOGY

SYMPTOMS/EXAM

■ Petechiae or ecchymosis of mucus membranes or skin
■ Epistaxis, gum bleeding, menorrhagia, or GI bleeding

DIAGNOSIS

■ Increased bleeding may occur when platelets are below 50,000/μL.
■ Risk of life-threatening spontaneous hemorrhage occurs with counts
<20,000/μL and substantially increases with counts <10,000/μL.

TREATMENT

■ Treat underlying cause.
■ Significant hemorrhage or major procedure with platelets <50,000/μL

PK

HK

XII

XI

IX IXa

XX

XIII

XIIIa

Fibrinogen Fibrin

Cross-linked fibrin

Xa

VIIIa

Va

Prothrombin Thrombin

VIIa

TF

Extrinsic pathway

XIa

XIIa

Intrinsic pathway

HK

FIGURE 9.1. The coagulation cascade. The intrinsic pathway is measured by the
activated partial thromboplastin time (PTT). The extrinsic pathway is measured by the
prothrombin time (PT).

(Reproduced, with permission, from Lichtman MA, Beutler E, Kipps TJ, et al. Williams Hematology,
7th ed. New York: McGraw-Hill, 2006:1684.)

TABLE 9.6. Use of Laboratory Values to Identify Cause of Increased Bleeding

LABORATORYFINDING CAUSES

Low platelets See Table 9.9.

Prolonged PT Liver disease, vitamin K deficiency, warfarin

Prolonged PTT Hemophilia A and B, von Willebrand disease, heparin

Low fibrinogen level Disseminated intravascular coagulation, large volume

transfusion, liver disease, severe malnutrition

Patients with clotting-factor

problems tend to suffer from

prolonged bleeding after an

injury or surgery and bleeding

into joints; patients with

platelet problems tend to

suffer from petechiae,

epistaxis, gum bleeding, and

vaginal bleeding.

Thrombocytopenia in patients

with alcoholism results from

direct toxicity to the bone

marrow from alcohol, folic

acid deficiency, and increased

sequestration from

splenomegaly.