Monday, April 9, 2012

Thrombocytopenia - Apr 9, 2012


Thank you to Dr. Alan Detsky for doing morning report on Thursday April 5.  Unfortunately, I was post-call and did not blog.

Today, we thank Dr. David Frost for hosting morning report and thank you to team 5 for bringing the case.

We discussed a case of a 75 year-old woman who presented with bleeding for 2 days after a dental procedure and found to have severe thrombocytopenia (platelet count of 1, Hb 91, MCV 75, WBC 4.4), with normal INR and PPT.  We discussed the approach to the bleeding patients include thrombocytopenia/platelet dysfunction or coagulopathy.  In our case, it is thrombocytopenia that is the major issue.  We discussed the major life threatening diagnoses that must be ruled out overnight:  ITP, TTP/HUS, DIC, HIT, drugs.  Other causes may be related to drugs, malignancy (especially lymphoma), infections (e.g. HIV, Hep C), and autoimmune disorders (e.g. SLE).

One of the most important investigations (other than CBC and coagulation parameters) is the blood film.  The diagnosis and management of the patient will be very different if schistocytes (or fragments) are present.  In the absence of fragments on blood film, normal coagulation studies, no signs of hemolysis (LDH, bilirubin, haptoglobin), no heparin or other drug exposure, the initial diagnosis overnight was ITP.

The management focuses on stopping the bleeding, and therapy for ITP.  Whereas it is controversial in patients with ITP who are not actively bleeding, patients who are actively bleeding may benefit from platelet transfusion.  Acutely, therapy for ITP includes steroids (prednisone or dexamethasone), and/or IVIG (IVIG in combination with steroids will raise platelet count quicker).  Other options sometimes used with the help of a hematologist include other agents (e.g. rituximab, vincristine, etc…), and splenectomy.  Newer agents in the future may include thrombopoietin receptor agonists that stimulate platelet production.

In the patient discussed, it is important to exclude secondary causes given her age and anemia.  Secondary causes include infection (e.g. HIV, HCV), malignancy (e.g. lymphoproliferative disorder), drugs, and autoimmune diseases (SLE, APLA, Evans syndrome, etc…).  Appropriate investigations (serologies, bone marrow) are required.

You can read the 2011 American Society of Hematology evidence-based practice guideline for ITP here.

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