Thrombocytopenia
Thrombocytopenia is defined as a platelet count of <150,000. Mild (100,000–150,000) and moderate (50,000–100,000) thrombocytopenia are rarely associated with significant bleeding. In contrast to the deep muscle and joint bleeds seen with coagulation factor deficiencies, clinical manifestations of bleeding due to thrombocytopenia involve skin or mucous membrane, GI tract, and menstrual bleeding. A rare but devastating consequence of a low platelet count is intracranial hemorrhage.
Differential Diagnosis
Disorders of increased destruction
- Immunologic platelet consumption
–Immune thrombocytopenic purpura (ITP)
–Drug-induced (antiepileptics, septra)
–Infection (EBV, CMV, malaria, Parvovirus, HIV, other viral illnesses)
–Autoimmune disease (SLE)
–Evans syndrome: ITP with immune
hemolytic anemia
–Allergy or anaphylaxis
–Posttransplant
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Nonimmunologic
–Chronic microangiopathic hemolytic anemia
–Hemolytic-uremic syndrome (HUS)
–Thrombotic thrombocytopenic purpura
–Shear (catheters, cardiopulmonary bypass, congenital or acquired heart disease)
Disorders of decreased production
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Bone marrow infiltration: Leukemia, neuroblastoma, histiocytosis, osteopetrosis
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Marrow failure: Aplastic anemia, congenital microangiopathic anemia, thrombocytopenia with absent radii (TAR), Fanconi anemia, myelodysplasia, amegakaryocytic thrombocytopenia
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Abnormal platelet size or morphology
–Bernard-Soulier
–May-Hegglin
–Gray platelet
–Wiskott-Aldrich
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Severe nutritional deficiency
–B12, folate
Combined disorders
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DIC, Kasabach-Merritt syndrome, storage diseases, renal disease, pre-eclampsia
Sequestration
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Hypersplenism/portal hypertension, thrombosis, cavernous transformation of portal vein, hypothermia
Neonatal
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Congenital anomalies (trisomy 13 or 18)
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Maternal causes: ITP, SLE, HELLP syndrome, DIC, hyperthyroidism, viral illness, drug use
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NEC
Workup and Diagnosis
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History: Recent illness, diet history; bleeding (nose, gum, stool, urine, skin, duration, amount); bone pain, fever, lethargy or crankiness, limp; HIV risk factors, diet history; exposure to toxins or radiation
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Medical history: Congenital anomalies; bleeding with previous surgery or trauma, menorrhagia; frequent infections, congenital cyanotic heart disease
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Family history: Thrombocytopenia; autoimmune or collagen vascular diseases; blood dyscrasias, hematologic malignancies; storage diseases
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Physical exam
–General appearance, growth
–Petechiae, purpura, ecchymoses, eczema, pallor
–Jaundice, nail dystrophy
–Lymph node chains
–Splenomegaly, hepatomegaly, bruit, masses
–Caput medusae or spider hemangiomas
–Palatal petechiae, gum bleeding, leukoplakia
–Absent radii, thumb anomalies, joint abnormalities
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Studies
–Bone marrow exam
–Abdominal ultrasound; chest X-ray
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Labs
–All patients: CBC/diff with peripheral smear
–Selected patients: direct and indirect Coombs, LDH,
DIC panel (PT/PTT, fibrinogen, D-dimers), blood culture, HIV, ANA, urinalysis, renal function, CMV and EBV titers, hepatitis B and C serologies
Treatment
- Dependent upon etiology, severity, and presence of acute bleeding
- ITP
–Bone marrow exam before treatment with steroids
–Treatment with IVIG or WinRho does not need bone marrow exam
–Platelet transfusion is ineffective in ITP but should be considered at counts <20,000 in the neonate or with life-threatening hemorrhage
–Severe injury is unlikely if count >10,000
–Treatment does not hasten resolution of ITP
–About 90% of children have resolution in 3–6 months
–Older girls more likely to become chronic
- Acute, isolated thrombocytopenia is almost never malignancy
–Marrow exam should be done in children with chronic or complex illness or with no response to therapy
