From the Guidelines
For a pediatric patient with nosebleeds, I recommend ordering a complete blood count (CBC) with differential, coagulation studies including prothrombin time (PT), partial thromboplastin time (PTT), and international normalized ratio (INR), as well as a von Willebrand factor assay, as these tests are crucial in identifying underlying hematologic disorders that may cause recurrent epistaxis, as suggested by the clinical practice guideline for nosebleed management 1.
Key Laboratory Tests
- Complete blood count (CBC) with differential to evaluate for anemia, thrombocytopenia, or leukemia
- Coagulation studies, including prothrombin time (PT), partial thromboplastin time (PTT), and international normalized ratio (INR), to detect clotting abnormalities
- Von Willebrand factor assay, as von Willebrand disease is the most common inherited bleeding disorder in children
- Blood type and screen, ferritin level, and possibly a platelet function analysis for further evaluation
Additional Considerations
- For severe or recurrent nosebleeds, consider adding liver function tests to rule out liver disease affecting clotting factor production
- If there's a family history of bleeding disorders or the patient has other bleeding symptoms (easy bruising, gum bleeding, prolonged bleeding from minor cuts), these laboratory evaluations become even more critical for proper diagnosis and management, as emphasized in the clinical practice guideline for nosebleed management 1
Rationale
The recommended laboratory tests are essential in identifying underlying causes of nosebleeds in pediatric patients, which is crucial for effective management and prevention of recurrent episodes, as well as reducing the risk of complications and improving quality of life, as highlighted in the clinical practice guideline for nosebleed management 1.
From the Research
Laboratory Tests for Pediatric Patients with Nosebleeds
To evaluate a pediatric patient with nosebleeds, the following laboratory tests can be ordered:
- Complete blood count (CBC) to evaluate for anemia, thrombocytopenia, or other abnormalities in blood cell counts 2, 3, 4
- Platelet count to assess for thrombocytopenia or platelet function disorders 2, 3, 4
- Prothrombin time (PT) and activated partial thromboplastin time (aPTT) to evaluate the coagulation cascade and identify potential factor deficiencies or inhibitors 2, 5, 3, 6, 4
- Peripheral blood smear to evaluate platelet morphology and detect any abnormalities in blood cell morphology 2, 3, 4
Specialized Tests
If initial laboratory tests are abnormal or if there is a high suspicion for a bleeding disorder, the following specialized tests can be ordered:
- Von Willebrand factor antigen and activity assays to diagnose von Willebrand disease 2, 3, 4
- Factor VIII assay to evaluate for hemophilia A or other factor VIII deficiencies 2
- Mixing studies to evaluate for factor deficiencies or inhibitors 3, 6, 4
- Platelet Function Analyzer-100 to evaluate platelet function 4
- Inhibitor assays to evaluate for factor inhibitors 4
Interpretation of Laboratory Results
Abnormal laboratory results can indicate a variety of bleeding disorders, including:
- Von Willebrand disease: characterized by a prolonged aPTT, low von Willebrand factor antigen and activity, and a normal PT 2, 3, 4
- Hemophilia A: characterized by a prolonged aPTT, low factor VIII activity, and a normal PT 2
- Platelet function disorders: characterized by a normal PT and aPTT, but abnormal platelet function tests 3, 4
- Factor deficiencies or inhibitors: characterized by a prolonged PT and/or aPTT, and abnormal mixing studies or inhibitor assays 3, 6, 4