Tuesday, January 20, 2009

Thrombocytopenia: an approach

(a megakaryocyte pictured on the left)

Look for mucocutaneous bleeding: gingival bleeding after brushing teeth, epistaxis, menorrhagia, metrorrhagia, and easy bruising. Also look for petichiae (non-palpable, non-blanchable) in dependent areas, like the shins and feet. These should not be on the soles of the feet as there is a thick protective layer of subcutaneous tissue. You may see them on the palate as well. Check out the photos at the bottom.

Decreased Production of platelets:

  • Hypocellular bone marrow: from aplastic anemia of which there are many causes(idiopathic, radiation, chemo, medications, viruses). Other cell lines will also be decreased.

  • Cellular bone marrow: myelodysplastic syndromes, leukemia

  • Replacement of marrow: with primary or secondary malignancies, myelofibrosis, or granuloma (eg. TB, sarcoid).

you can read more about related issues here.

Increased Destruction of platelets:

  • Immune mediated: Idiopathic Throbocytopenia Purpura (primary), or secondary to Collagen Vascular Diseases (eg. SLE), Infections (eg. HIV, Hep C), Drugs (eg. heparin, sulfa), Lymphoproliferative diseases (CLL, lymphoma), and the Antiphospholipid Antibody Syndrome.

  • Non-Immune mediated: Think about things like Disseminated Intravascular Coagulation, Thrombotic Thrombocytopenia Purpura and it's cousin the Hemolytic Uremic Syndrome, HELLP syndrome in pre-eclampsia, and malignant hypertension.


  • Mostly in a large spleen.


  • Very rarely, blood collected in the tube will react to a chemical (EDTA) and cause platelet clumping - this may cause 'spurious' thrombocytopenia. The platelets work just fine, they just react to the EDTA.

(petichiae to the left, and palatal petichia + gingival bleeding below)

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