Drug-induced Thrombocytopenia

by Carlo Raj, MD

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    00:01 Drug-induced thrombocytopenia.

    00:02 If you missed our discussion on heparin, please make sure that you refer to our hematology hemodynamic pharmacology where I talked about in great detail the possibility when given heparin at the site of injection where there's a possibility in sub-set of population in which may then activate the platelet via platelet factor IV.

    00:21 And by doing so, you may then form a thrombi formation and result in thrombocytopenia.

    00:25 Other causes, quinidine class 1A sodium-channel blocker, sulphas, methyldopa.

    00:32 That'll be in alpha 2 agonist that you may then give a pregnant lady who has hypertension prior, was on ACE inhibitor, obviously, needs to remove that, right? Because ACE inhibitor will kill the kidneys of the fetus or teratogen.

    00:45 And unfortunate the patient may then develop thrombocytopenia.

    00:50 Also penicillins and also thiazide diuretics.

    00:55 HIV-associated thrombocytopenia.

    01:00 This is important.

    01:01 So now you have antibodies formed against HIV antigen.

    01:05 The gp120 cross-react with the platelet surface antigen.

    01:11 In other words, we have example of molecular mimicry of IIb/IIIa.

    01:15 Unbelievable.

    01:17 And now what happens is the antibodies bind to the platelet which are then cleared by the spleen.

    01:22 The particular antigen or chemokine that you wanna know that allows for entry of HIV in the platelet, if you remember from microbiology it's called CXCR4.

    01:34 Keep that in mind please.

    01:36 But at this point, in pathology with HIV, take a look at molecular mimicry with gp120 if you remember that from your HIV discussion.

    About the Lecture

    The lecture Drug-induced Thrombocytopenia by Carlo Raj, MD is from the course Hemostasis: Basic Principles with Carlo Raj.

    Included Quiz Questions

    1. Binding of antibodies to complexes of heparin and platelet factor 4, causing platelet activation and promoting a prothrombotic state
    2. Immunoglobulin G antibodies against platelet membrane glycoproteins IIb-IIIa or Ib-IX, causing platelet destruction
    3. Massive systemic intravascular activation of coagulation, leading to widespread deposition of fibrin in the circulation
    4. Systemic deposition of platelet thrombi with abundance of von Willebrand factor (vWF) due to autoimmune destruction of ADAMTS13
    5. Infiltration and replacement of normal marrow space by nonhematopoietic or abnormal cells
    1. Human immunodeficiency virus
    2. Plasmodium falciparum
    3. Neisseria meningitidis
    4. Hepatitis C virus
    5. Mycobacterium tuberculosis

    Author of lecture Drug-induced Thrombocytopenia

     Carlo Raj, MD

    Carlo Raj, MD

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