# Thrombocytopenia Approach > Thrombocytopenia approach for NEET-PG Medicine covers pseudo, production, destruction and sequestration causes, smear reading and bleeding thresholds. - Canonical URL: https://prepelephant.com/topics/neet-pg/medicine/thrombocytopenia-approach - Exam / course: NEET-PG · Subject: Medicine - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-14 - Last updated: 2026-10-14 - Reference basis: Harrison's Principles of Internal Medicine; Hoffbrand's Essential Haematology; Dacie and Lewis Practical Haematology - How to cite: "Thrombocytopenia Approach", PrepElephant, https://prepelephant.com/topics/neet-pg/medicine/thrombocytopenia-approach ## Direct answer Thrombocytopenia is a platelet count below 150 × 10^9 per litre, and it is classified by mechanism as pseudo-thrombocytopenia, production failure, destruction or sequestration. Immune destruction is a leading mechanism in many cases, though consumption, dilution, sequestration and drugs are also important. Management depends on the cause and on the count, because spontaneous bleeding becomes a real risk only when platelets fall below about 10 to 20 × 10^9 per litre. ## What you must remember - **Pseudo-thrombocytopenia:** EDTA-dependent platelet clumping gives a falsely low count, so the smear and a citrate-tube repeat come first. - **Production failure:** marrow aplasia, megaloblastic anaemia, leukaemia, myelodysplasia, alcohol and HIV reduce platelet output. - **Destruction:** immune thrombocytopenia, TTP, HUS, DIC, heparin-induced thrombocytopenia, SLE and dengue are the key examples. - **Sequestration:** hypersplenism from portal hypertension or splenomegaly traps platelets in the spleen. - **Dilution:** massive transfusion lowers the count, and the cause is usually clear from the clinical setting. - **Bleeding threshold:** spontaneous bleeding risk rises steeply below about 10 to 20 × 10^9 per litre, and immune thrombocytopenia is commonly treated below about 30 × 10^9 per litre. - **Schistocytes:** their presence on the smear points to microangiopathic haemolysis such as TTP, HUS or DIC. ## Approach to an isolated low platelet count A 28-year-old woman with petechiae and a platelet count of 42 × 10^9 per litre has no fever and a normal haemoglobin. The first question is whether the low count is real, and the second is which mechanism is responsible. 1. **Exclude pseudo-thrombocytopenia:** examine the smear for clumps and repeat the count in a sodium citrate tube, since EDTA-dependent antibodies produce spurious results. 2. **Read the smear:** schistocytes point to microangiopathy, while giant platelets suggest an inherited macrothrombocytopenia rather than an acquired cause. 3. **Check the other lines:** anaemia, neutropenia or circulating blasts suggest a production problem and prompt bone marrow examination. 4. **Look for consumption:** a prolonged prothrombin time, prolonged aPTT and low fibrinogen with raised D-dimer indicate DIC, while raised LDH and low ADAMTS13 activity indicate TTP. 5. **Assess the spleen and drugs:** splenomegaly with portal hypertension suggests sequestration, and a fall in count 5 to 10 days after heparin exposure suggests heparin-induced thrombocytopenia. 6. **Decide on treatment by cause and count:** immune thrombocytopenia is treated when the count is low or bleeding occurs, and platelet transfusion is reserved for active bleeding or procedures. ## Where the exam tries to catch you Thrombocytopenia questions often turn on one quiet detail, such as a clumped sample or a schistocyte. - **Trap:** transfusing platelets for a count of 40 without checking the sample — **Correct:** clumping must be excluded, since transfusion is wasted on a spurious count. - **Trap:** treating a patient with TTP as immune thrombocytopenia — **Correct:** TTP needs urgent plasma exchange, with corticosteroids added rather than used alone. - **Trap:** continuing heparin because the count is low — **Correct:** heparin-induced thrombocytopenia causes thrombosis, so all heparin, including flushes, is stopped. - **Trap:** transfusing platelets for every low count in dengue — **Correct:** transfusion is guided by bleeding and a very low count, as set out in national dengue guidance. ## Frequently asked questions ### At what platelet count does spontaneous bleeding usually occur? Spontaneous bleeding risk rises steeply when the platelet count falls below about 10 to 20 × 10^9 per litre. Major surgery is commonly planned when the count is above about 50 × 10^9 per litre, although the threshold depends on the procedure. Other coagulation factors and vascular causes also influence bleeding. ### How is pseudo-thrombocytopenia identified? Pseudo-thrombocytopenia is identified by examining the peripheral smear for platelet clumps and repeating the count in a sodium citrate tube. EDTA-dependent antibodies cause in-vitro clumping in EDTA samples and falsely low counts. The true platelet count is normal, so no treatment is needed for the spurious result. ### What distinguishes immune thrombocytopenia from TTP on a blood film? Immune thrombocytopenia shows a low platelet count with normal red cell morphology and no schistocytes. Thrombotic thrombocytopenic purpura, or TTP, shows microangiopathic haemolytic anaemia with schistocytes, neurological features, renal impairment and fever. TTP is diagnosed with ADAMTS13 testing and treated urgently with plasma exchange. ### Why is heparin stopped in suspected heparin-induced thrombocytopenia? Heparin-induced thrombocytopenia is an immune reaction that activates platelets and causes thrombosis, so heparin must be stopped even though the count is low. It typically develops 5 to 10 days after exposure. An alternative non-heparin anticoagulant is then used, and heparin flushes are avoided as well. ### When is platelet transfusion indicated in dengue? Platelet transfusion in dengue is guided mainly by active bleeding and a very low platelet count, not by the number alone. Routine transfusion for every low count is not supported by national dengue guidance. Clinicians also watch closely for plasma leakage, which shapes the level of care.