Thrombocytopenia¶
Robert Dunn
Background¶
- Platelet count <150k (mild), 50-100k (moderate), <50k (severe)
- Framework for differential: consumption, sequestration, destruction, production
- Causes to consider:
- Can’t Miss Diagnoses: TTP, HUS, HELLP, DIC, HIT
- Platelet clumping (lab artifact - pseudothrombocytopenia)
- Splenomegaly can represent: Plt sequestration, cirrhosis, portal hypertension
- Drug-induced: (Antibiotics, heparin, chemo, GpIIb/IIIa antagonists, H2-antagonists)
- Rheumatologic cause – SLE, sarcoidosis, scleroderma renal crisis
- Sepsis, independent of DIC
- Immune thrombocytopenia (ITP) is a diagnosis of exclusion
- Massive physiologic consumption: large hematoma, active hemorrhage
- Cirrhosis – results in low thrombopoietin (TPO) and increased clearance
- Chronic alcohol use – direct marrow suppression
- Infections: HIV, HCV, EBV, Parvovirus, Rickettsia, H. pylori, CMV
- Bone marrow failure: aplastic anemia, MDS, leukemia, chemotherapy
- Dilutional: fluid resuscitation and massive transfusion
Presentation¶
- Petechiae – typically begins distally on lower legs (in mouth = wet purpura), seen when \<10-20k
- Overt bleeding, mucosal bleeding, epistaxis (seen when \<20k)
Evaluation¶
- CMP, CBC w/diff, peripheral smear, citrated platelet count, immature platelet fraction (IPF)
- LDH, Fibrinogen, d-dimer, PT/aPTT
- Determine timing of decline as well as prior values
- Look at other cell lines - never normal to have two cytopenia’s
- Review recent initiation of drugs: (heparin, antibiotics, and chemotherapy)
- Consider abdominal ultrasound to look for splenomegaly and liver pathology
- Infectious work up (HIV, HCV)
- Calculate 4T Score and consider your pretest probability for HIT testing
- HIT Ab: ELISA is first test – only run once/day at VUMC so order early if considering
- Reflex Serotonin release assay (SRA) for confirmation (VUMC performs reflexive testing)
Management¶
- Plt <50k
- Discontinue pharmacologic DVT prophylaxis (unless HIT)
- If on anticoagulation: consider risk/benefits of continued
anticoagulation
- Can transfuse plt’s if AC is mandatory
- Plt <10k
- Transfuse platelets given risk of spontaneous intracranial hemorrhage
- In pt’s with HIT or TTP, there is theoretical concern that
transfusing plt can “fuel the fire” and lead to more thrombosis, but
if there is active bleeding then consider platelets
- Therefore, bleeding with HIT or TTP, discuss with Hematology before transfusion
- HIT
- If pretest probability is high or HIT is confirmed
- Stop Unfractionated and low molecular weight heparin products
- Start Argatroban gtt
- If schistocytes present on peripheral smear = concern for TTP
- Draw ADAMTS13
- Contact Nephrology and Hematology for PLEX
Additional Information¶
- Clumping on lab draws:
- Obtain Citrated platelet (“blue top” tube – CPRS refers to it as a blue top platelet count)
- If no resolution, obtain a "Gold top" LAB 301 in Epic (Named: Plt count) (ACD tube)
Last update:
2022-06-24 23:35:57