Hematology

Thrombocytopenia

Background

1. Definition
   • < 150,000 platelets/microL [150 x 10⁹/L] for adults
     • Mild: 100,000-150,000/microL
     • Moderate: 50,000-99,000/microL
     • Severe: < 50,000/microL
2. Synopsis
   • Most common hemostatic disorder in critically ill patients
   • Symptomology
     • > 50,000 per microL typically asymptomatic
     • 30,000-50,000 per microL may have purpura
     • 10,000-30,000 per microL can have bleeding with minimal trauma
     • < 5000 per microL can have spontaneous bleeding (hematologic emergency)
   • One approach
     • Direct treatment to underlying condition (e.g. discontinue drug, underlying infection, IgG replacement, chemotherapy directed at CLL)
   • If cause unknown and no contraindications (i.e., infections)
     • Corticosteroids
   • More specific treatment depends on underlying etiology

Pathophysiology

1. Mechanism
   • Possible resultant condition due to
     • Decreased platelet production (bone marrow)
     • Peripheral platelet destruction by antibodies
     • Consumption in thrombi
     • Dilution from fluid resuscitation
     • Massive transfusion
     • Sequestration of platelets in the spleen (portal hypertension and/or splenomegaly)
   • Pseudothrombocytopenia
     • Secondary to platelet clumping
     • No clinical significance
     • It occurs in 1 in 1,000 persons in general population
     • Confirmed by peripheral blood smear
     • Etiology
       • Abciximab (ReoPro), ethylenediaminetetraacetic acid-dependent agglutinins
     • Platelet count should be repeated; use non-ethylenediaminetetraacetic acid anticoagulant tubes when collecting samples (i.e., heparin or sodium citrate)
     • If CBC still shows thrombocytopenia, investigate other causes
2. Etiology/Risk Factors
   • Bone marrow disorders
   • Liver disease
   • Drug-induced
   • Hemodilution (in patients with massive hemorrhage and have received colloids, crystalloids, and platelet-poor blood products)
   • Associated with a higher risk of thrombocytopenia developing in the ICU:
     • A high severity of illness
     • Prior surgery
     • Use of inotropes or vasopressors
     • Renal replacement therapy
     • Liver dysfunction
   • LMWH thromboprophylaxis is associated with a lower risk
3. Epidemiology
   • Incidence/Prevalence
     • There are > 200 diseases that include low number of platelets
     • Variable; depends on the type of and condition leading to thrombocytopenia
   • Mortality/Morbidity
     • Patients who develop thrombocytopenia in the ICU are more likely to bleed, receive transfusions, and die

Diagnostics

1. History/Symptoms
   • Easy bruising, bleeding
   • Ask about
     • Melena, rashes, fevers
     • Medication use, immunizations
     • Recent travel
     • Transfusion history, family history, medical history
2. Physical Exam/Signs
   • Physical exam may be normal or show petechiae, ecchymoses
   • Underlying conditions will show varying signs
     • Lymphadenopathy
     • Jaundice
     • Skin rashes
     • Splenomegaly
     • Hepatomegaly
3. Labs/Tests
   • CBC +Diff
   • Platelet count
   • LFTs
   • LDH
   • Coag panel
   • D-dimer
4. Imaging
   • Not usually indicated unless concern/suspect internal injury
5. Other Tests/Criteria
   • Peripheral Blood Smear
   • Serology for viral etiology
6. Differential Diagnosis
   • Purpura
   • Malignancy
   • Liver dysfunction
   • Bone marrow disease
   • Drug-induced
   • VWD
   • Hemophilia
   • Coagulation factor deficiencies other than hemophilia

Treatment

1. Initial/Prep/Goals
   • Direct therapy based on underlying condition if possible
   • If unknown cause or idiopathic, symptomatic therapies
2. Medical/Pharmaceutical
   • Platelet transfusion after IVIG
   • Systemic corticosteroids if no contraindications
3. Surgical/Procedural
   • Usually not indicated unless suspect underlying conditions as needed
4. Complications
   • Infection from transfusion
   • Transfusion rejection
5. Prevention
   • Genetic counseling
   • Manage underlying conditions

Disposition

1. Admission Criteria
   • Admit if patients are ill appearing
   • Emergent thrombocytopenia
   • Per hematologist recommendation
2. Consult(s)
   • Hematology, oncology, etc. as needed
3. Discharge/Follow-up Instructions
   • With mild bleeds that shows sign of coagulation and with observation can discharge
     • With follow-up with PCP in 2-3 days

References

1. Gauer RL, Braun MM. Thrombocytopenia. Am Fam Physician. Mar 15, 2012;85(6):612-622
2. Williamson DR, Albert M, Heels-Ansdell D, Arnold DM, et al. Thrombocytopenia in critically ill patients receiving thromboprophylaxis: frequency, risk factors, and outcomes. Chest. Oct 2013;144(4):1207-1225
3. Izak M, Bussel JB. Management of thrombocytopenia. F1000Prime Rep. Jun 2014;6:45
4. Stasi R. How to approach thrombocytopenia. Hematology Am Soc Hematol Educ Program. Dec 2012;2012(1):191–197

Contributor(s)

1. Ho, Nghia, MD

Updated/Reviewed: July 2020