Thrombocytopenia
Background
- Thrombocytopenia is defined as platelets of less than 150 x 103/mcL. Symptoms such as bruising and petechiae usually occur at counts at 50 x 103/mcL and between 5-10x 103/mcL there is a high risk of spontaneous bleeding.
Clinical Features
- Nonpalpable petechiae/purpura
- Mucosal bleeding (gingival, epistaxis)
- Menorrhagia, hemoptysis, hematuria, hematochezia
- Deep tissue/joint bleeding is less common (more likely due to coagulopathies)
Differential Diagnosis
Thrombocytopenia
Decreased production
- Marrow infiltration (tumor or infection)
- Viral infections (rubella, HIV)
- Marrow suppression (commonly chemotherapy or radiation)
- Congenital thrombocytopenia
- Fanconi anemia
- Alport syndrome
- Bernand Soulier
- Vitamin B12 and/or folate deficiency
Increased platelet destruction or use
- Idiopathic thrombocytopenic purpura
- Thrombotic Thrombocytopenic Purpura (TTP)
- Hemolytic Uremic Syndrome (HUS)
- Disseminated Intravascular Coagulation (DIC)
- Viral infections (HIV, mumps, varicella, EBV)
- Drugs (heparin, protamine)
- Postransfusion or Posttransplantation
- Autoimmune destruction (SLE or Sarcoidosis)
- Mechanical destruction
- Artificial valves
- ECMO
- HELLP syndrome
- Excessive hemorrhage
- Hemodialysis, extracorporeal circulation
- Splenic Sequestration
- Occurs in Sickle cell disease and Cirrhosis
Drug Induced
- sulfa antibiotics, ETOH, ASA, thiazide diuretics/furosemide
Comparison by Etiology
ITP | TTP | HUS | HIT | DIC | |
---|---|---|---|---|---|
↓ PLT | Yes | Yes | Yes | Yes | Yes |
↑PT/INR | No | No | No | +/- | Yes |
MAHA | No | Yes | Yes | No | Yes |
↓ Fibrinogen | No | No | No | No | Yes |
Ok to give PLT | Yes | No | No | No | Yes |
Coagulopathy
Platelet Related
- Too few
- Nonfunctional
Factor Related
- Acquired (Drug Related)
- Warfarin (Coumadin)
- Unfractionated heparin
- Low molecular weight heparin (i.e. enoxaparin (Lovenox), dalteparin)
- Factor Xa Inhibitors (e.g. rivaroxaban, apixaban, fondaparinux, edoxaban)
- Direct thrombin inhibitors (e.g. dabigatran, argatroban, bivalirudin)
- Illness induced
- Genetic
Evaluation
- Platelet count (CBC)
- Additional workup per clinical presentation
Management
Patient treatments are stratified by the presence or absence of bleeding and in the non bleeding patient by the platelet number and the presumed cause of the thrombocytopenia
Platelet Transfusion Thresholds
most if not all of the following thresholds are based on weak recommendations with low quality evidence[1]
- <50K if planned lumbar puncture or neurosurgical procedure[2]
- <20K if planned for central venous catheter placement (preference toward compressible site), or febrile patient
- <10K in asymptomatic patients (unless due to ITP, TTP, or HIT)
There are no firm recommendations for transfusion thresholds in acute traumatic bleeding but many providers will opt for a goal of 100K, especially if there is evidence of ICH
Transfusion contraindications
Pediatrics
- 1 unit of platelets per 5kg body weight raises count by 50k