Chapter 37 PURPURA
Medications Associated with Purpura
• Alkylating agents (decreased platelet formation)
• Antimetabolites (decreased platelet formation)
• Anticonvulsants (decreased platelet formation)
• Aspirin (platelet dysfunction)
• Chloral hydrate (vascular purpura)
• Chlorothiazide diuretics (decreased platelet formation)
• Cimetidine (immune thrombocytopenia)
• Clofibrate (platelet dysfunction)
• Corticosteroid therapy long term (defective vascular support tissue)
• Estrogens (decreased platelet formation)
• Furosemide (platelet dysfunction)
• Heparin (immune thrombocytopenia, platelet dysfunction)
• Nitrofurantoin (platelet dysfunction)
• Nonsteroidal anti inflammatory drugs (NSAIDs; platelet dysfunction)
• Penicillin (immune thrombocytopenia)
• Quinidine (immune thrombocytopenia)
• Sulfonamides (immune thrombocytopenia)
Causes of Purpura
Acquired coagulation factor deficiency
Hereditary deficiency of any coagulation factor. The most common are:
Key Historical Features
Key Physical Findings
Vital signs, noting fever or hypertension
Growth parameters and comparison with previous measurements
General evaluation of well-being
Evaluation for lymphadenopathy
Abdominal examination for tenderness or hepatosplenomegaly
Genitourinary examination for scrotal edema
Extremity examination for edema, palmar erythema, or evidence of hemarthrosis
Suggested Work-up
| Complete blood count (CBC) | To evaluate for thrombocytopenia or anemia |
| Peripheral blood smear | To evaluate for schistocytes suggesting hemolytic-uremic syndrome, thrombotic thrombocytopenia purpura, or disseminated intravascular coagulopathy. To evaluate for neutrophilia suggesting an infection. |
| Prothrombin time (PT) | To evaluate for a deficiency involving coagulation factors II, V, VII, X, or fibrinogen |
| Activated partial thromboplastin time (aPTT) | To evaluate for a deficiency involving coagulation factors II, V, VIII, IX, X, XI, XII, or fibrinogen |
Additional Work-up
| Bleeding time | Rarely indicated in children. Measures the interval required for bleeding to stop after a standardized incision is made on the forearm. |
| Measurements of specific coagulation factors or von Willebrand factor | To confirm a specific factor deficiency or von Willebrand disease |
| Platelet aggregation tests using activators, clot retraction, prothrombin consumption test, and serotonin release | If a platelet function defect is suspected |
| Bone marrow biopsy | If a second bone marrow cell line is depressed or if the cause of thrombocytopenia is not clear after initial evaluation |
| Rheumatoid factor and antinuclear antibody | If the patient has arthritis or arthralgias |
| Urinalysis | To evaluate for hematuria if Henoch-Schönlein purpura, systemic lupus erythematosus, or hemolytic-uremic syndrome is suspected |
| Blood urea nitrogen (BUN), creatinine, and urinalysis | If renal disease is suspected |
| Liver function tests | If liver disease is suspected |
| Abdominal ultrasonography or computed tomography (CT) scanning | If organomegaly is present |
| Cranial ultrasound | To evaluate for intracranial bleeding if the neonatal platelet count is less than 50 × 103 per μL |
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