Info
🌱 來自: Huppert’s Notes
Quantitative Platelet Disorders🚧 施工中
Quantitative Platelet Disorders
Thrombocytopenia
• Definition*:* Low number of platelets (<150K/μl)
• Symptoms*:* Easy bruising or bleeding (e.g., mucosal bleeding such as gingiva or nasal mucosa, heavy menses, petechiae)
• Work-up*:*
- Get a peripheral blood smear:
• Rule out pseudothrombocytopenia (platelet clumping), which can occur in the blood tube when the anticoagulant EDTA is present, causing a spuriously low platelet count. Evaluate by looking for platelet clumping on the blood smear. Resend platelets in a heparin or sodium citrate tube if needed.
• Giant platelets can be falsely counted by the automated cell counter as WBCs or RBCs. Large platelets can occur with inherited platelet disorders.
- Take a thorough history:
• History of easy bleeding or bruising?
• Systemic symptoms – fever, headache, abdominal pain, hematuria, diarrhea? These symptoms can occur with HUS or TTP.
• Medications? In the hospital, consider heparin products, antibiotics, immunosuppressants.
• History of autoimmune conditions? A history of autoimmune conditions makes ITP more likely.
- Also check PT, PTT, reticulocyte count, fibrinogen, LDH, TSH, HIV, HCV, and other labs guided by the disease entity suspected
• Etiologies of thrombocytopenia: Consider three buckets:
- Decreased production: Think about processes that cause bone marrow suppression or infiltration. Often multiple cell lines down!
• Aplastic anemia, MDS, leukemia, Fanconi syndrome, infiltrative disorders
• Medications/toxins: Alcohol, chemotherapeutic agents, chloramphenicol, benzene, radiation
• Infections: Parvovirus, EBV, CMV, HCV, HIV
• Nutritional deficiencies: B12 or folate deficiency
- Increased destruction: Divide causes by immune-mediated or non-immune mediated. Also see additional details about these conditions in the section below.
• Immune-mediated
- Primary: ITP
- Secondary: HIT, other medications (antibiotics, H2 blockers), infections, lupus, APS, lymphoproliferative disease
• Non-immune-mediated
- Microangiopathic hemolytic anemia (MAHA): HUS, TTP, DIC, scleroderma renal crisis
- HELLP
- Mechanical: CVVH
- Sequestration/dilutional
• Hepatosplenomegaly: Cirrhosis and portal HTN can sequester 90% of platelets
• Massive transfusion: 10U pRBCs decrease platelets by 50%