Approach to a pt with thrombocytopenia

Definition: definition of thrombocytopenia is a platelet count < 150 × 10E9/L

 

Presentation:

Often asymptomatic when first detected (significant or spontaneous bleeding rarely occurs with a platelet count > 50 × 10E9/L; 5-fold increase in risk <50 x 10E9/L)

Purpura, petechiae and bleeding from the gums and into the knee

Bleeding from venipuncture sites

Spontaneous intracerebral haemorrhage (<0.5% in ICU, higher risk if platelets <10 x 10E9/L)

Splenomegaly

 

Petechiae

Petechiae

                                             

Purpura

Purpura

 

Etiologies




Increased destruction

Immunologic: collagen vascular disease, infection, ITP, lymphoma/CLL, drugs (heparin, sulfonamides, aspirin, phenytoin, digoxin, vancomycin, B-lactam antibiotics)

Mechanical: TTP, HUS, DIC, chronic dialysis patient

Vasculitis

 

Decreased production

Decreased megakaryocytes: drugs (EtOH, thiazide, chemo, linezolid), toxins, infection, leukemia

Splenic sequestration

 

Dilutional

Massive transfusion, ECMO, exchange transfusion

 




Suggested work-up:

Repeat platelet count – Ensure value is accurate

CBC – TTP-HUS presents with anemia AND thrombocytopenia. Abnormal platelets and abnormal WBC count is concerning for primary hematologic etiology.

Peripheral smear (call the lab and ask them to add a peripheral smear) – Look for schistocytes, and also for platelet clumping to rule out pseudothrombocytopenia. 

PT/PTT/INR/fibrinogen – These will be abnormal in DIC and unaffected in other etiologies.

Consult Heme/onc

 

 

Whom to consider admitting:

Severe thrombocytopenia (i.e. < 20)

Platelet count drop > 50% of baseline

Suspected leukemia, TTP-HUS, or DIC

Active bleeding

 

Diagnosis to consider:

HITT

Heparin-induced thrombocytopenia AND thrombosis

Use the 4T score: Timing (5-10 days after heparin exposure), degree of Thrombocytopenia (> 50% drop from baseline), no other clear etiology, and Thrombosis

If intermediate probability, send anti-platelet (PF4) antibody test

If high probability, start alternative anti-coagulation with argatroban (hepatically-cleared) or bivalirudin (renally-cleared)

ITP

Dx of exclusion

Acute => child, viral prodrome days-weeks prior, platelets <20, self-limited, supportive care unless active bleeding (steroids, IVIG, anti-Rh Ig)

Chronic => adult, no prodrome, gradual, platelets 30-100

Life-threatening bleeding: plt transfusions, steroids, IVIG

 

TTP-HUS

Usually idiopathic but can be 2/2 meds (clopidogrel, ticlopidine, quinine) or infection (E. coli)

Thrombocytopenia + microangiopathic hemolytic anemia (pentad of fever, anemia, thrombocytopenia, renal involvement, and neuro involvement)

Acute management is with plasmapheresis

If not available FFP and arrange for transfer. NO PLATELETS.

 

Leukemia

Look for high white counts, but sometimes can present with leukopenia

Patients should be started on all-trans retinoid acid (ATRA) as soon as the diagnosis is suspected

When to transfuse platelets: <10 or <50 + active bleeding or <50 + invasive procedure. Of note: transfused platelets last 3-5 days.

 




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