UMEM Educational Pearls - Hematology/Oncology

Management of Heparin-Induced Thrombocytopenia (HIT)

HIT occurs when antibodies form to a Heparin-Platelet Factor 4 (PF4) complex in patients who have been exposed to Heparin. 

The main clinical manifestation is thrombosis (arterial/venous). Treatment is unique in that only certain medications can be used.

Medical Management options in HIT:

• Direct thrombin inhibitors (DTI). The main ones used in clinical practice include Argatroban and Hirudin. These drugs work by directly binding to thrombin (fibrin bound) and inhibiting it. The drugs are reliable and safe. Hirudin may initiate an allergic reaction in patients who have been exposed and is renally cleared (so shouldn't be used in ESRD or lower GFRs)
• Fondaparinux (Arixtra). Can be given subcutaneously. More expensive. Also approved for once daily treatment of DVT/PE

So, when a patient with a history of HIT shows up in the ED with a DVT/PE or other thrombotic problem, these are your mainstay drugs.

Multiple Myeloma + Altered Mental Status=Hyperviscosity Syndrome

Although the differential diagnosis of altered mental status is quite extensive, a patient with multiple myeloma and altered mental status should prompt consideration of one important, albeit not too common, condition.....hyperviscosity syndrome.

Some important pearls:

• This syndrome occurs when excessive amounts of protein (immunoglobulin) are secreted by myeloma (plasma) cells.
• Excessive circulating protein leads to sludging and ischemia in lung and brain tissue, lesding to hypoxia and altered mental status, respectively.
• You will only pick up this diagnosis by thinking about it, so multiple myeloma + altered mental status = hyperviscosity syndrome
• Treatment is with IVF and plasmapheresis (heme onc consult)
• And don't forget common stuff, like stroke, subdural hematomas, meningitis, etc.

A neutropenic cancer patient that presents with right lower quadrant abdominal pain, fever, and bloody diarrhea should raise suspicion for typhlitis (necrotizing colitis, cecal inflammation). This most commonly occurs in patients with hematologic malignancies who have been treated with cytotoxic agents. This condition is high risk and is associated with high morbidity and mortaiity.

Treatment:

• Broad-spectrum antibiotics
• CT scan of the abdomen and pelvis
• Surgical consultation
• Usually requires ICU admission

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Just a quick remainder that Thrombotic thrombocytopenia Purpura, TTP, is typically described as a pentad of symptoms:

1. Neurological symptoms such as altered mental status, stroke, or headache
2. Renal failure
3. Fever
4. Thrombocytopenia (low platelets) associated with purpura
5. Microangiopathic hemolytic anemia

Not all symptoms need to be present and it would be rare for you to see the full pentad.  Consider the diagnosis and request that the lab due a manual differentiation or blood smear.  It is there that they will notice schistocytes, fragmented RBCs, that will help clinch the diagnosis.

Most cases of TTP are idiopathic (~60%) but secondary TTP is known to occur with cancer, pregnancy, HIV, bone marrow transplantation, immunospressive drugs like cyclosporin and tacrolimus, and platelet aggregation inhibitors such as cloperidol.

Treatment consists of plasmapheresis, plasma exchange, immunospression with steroids, Rituximab, and other chemotherapies.