# A 70-year-old client has been receiving UFH IV continuous infusion for 7 days for a deep vein thrombosis. The morning labs and assessment show: platelets dropped from a baseline 240 K to 95 K (60% reduction), unilateral swollen and painful right calf with new positive Homans sign, no obvious bleeding. Which action by the nurse is most important? > source: MyMerci (mymerci.kr) > url: https://mymerci.kr/pages/nclex_q.php?qn_id=374955&lang=en > language: en > subject: Adverse Effects/Contraindications/Interactions > category: PA ## Question A 70-year-old client has been receiving UFH IV continuous infusion for 7 days for a deep vein thrombosis. The morning labs and assessment show: platelets dropped from a baseline 240 K to 95 K (60% reduction), unilateral swollen and painful right calf with new positive Homans sign, no obvious bleeding. Which action by the nurse is most important? ## Option 1. Maintain the current UFH infusion rate, carefully observe for any bleeding, plan to recheck the platelet count in 24 hours to see if it drops further, and interpret the new calf findings as an expected evolution of the deep vein thrombosis. 2. Stop ALL heparin (UFH and any LMWH/heparin flushes), notify the provider, anticipate orders for a non-heparin anticoagulant such as argatroban or fondaparinux, calculate the 4T score, and obtain HIT antibody (anti-PF4) plus confirmatory testing. **✔ Correct answer** 3. Discontinue the UFH infusion, start subcutaneous enoxaparin at a therapeutic dose because it reduces the risk of heparin-induced thrombocytopenia due to its smaller molecular size, and plan to check platelets in 48 hours. 4. Increase the UFH infusion rate to achieve a higher PTT level, believing that this will lyse the new thrombus in the right calf and prevent further clot extension; monitor for any signs of bleeding and recheck platelet count in 8 hours to evaluate for improvement. **Correct answer: 2** ## Explanation Heparin-Induced Thrombocytopenia (HIT) — recognition and management HIT is an immune-mediated reaction. IgG antibodies form against platelet factor 4 (PF4)–heparin complexes, activating platelets, causing simultaneous thrombocytopenia AND paradoxical thrombosis. Hallmarks: • Timing: typical onset Day 5–10 of heparin exposure (rapid-onset HIT can occur within 24 hours if previously exposed). • Thrombocytopenia: drop ≥50% from baseline OR absolute platelet count generally 30–100 K (rarely < 15 K — different from other thrombocytopenias). • Thrombosis: arterial or venous, including limb DVT, PE, MI, stroke, skin necrosis at injection sites. • Other causes ruled out. The 4T score (each item 0–2 points; total 0–8) stratifies clinical probability. Score ≥6 = high probability. Confirmation requires anti-PF4 ELISA plus a functional assay (serotonin release SRA — gold standard). Management: (1) Stop ALL heparin immediately — UFH, LMWH, heparin flushes (incl. line locks), heparin-coated catheters. (2) Start a non-heparin anticoagulant: argatroban (direct thrombin inhibitor, hepatic clearance — preferred in renal impairment), bivalirudin, or fondaparinux (Xa inhibitor; off-label but commonly used). (3) Send anti-PF4 antibody and confirmatory test. (4) Do NOT give platelets (would feed thrombosis); transfuse only for major bleed. (5) Avoid warfarin until platelets recover (>150 K) — early warfarin can cause venous limb gangrene. (6) Document HIT diagnosis prominently — lifetime heparin avoidance, allergy band. Continuing or increasing heparin (options 1, 3) feeds the disease; switching UFH to LMWH (option 3) does NOT help — HIT is a class effect (cross-reactivity ~85%). ## In-depth explanation Clinical reasoning summary Heparin-Induced Thrombocytopenia (HIT) — recognition and management HIT is an immune-mediated reaction. IgG antibodies form against platelet factor 4 (PF4)–heparin complexes, activating platelets, causing simultaneous thrombocytopenia AND paradoxical thrombosis. Hallmarks: • Timing: typical onset Day 5–10 of heparin exposure (rapid-onset HIT can occur within 24 hours if previously exposed). • Thrombocytopenia: drop ≥50% from baseline OR absolute platelet count generally 30–100 K (rarely < 15 K — different from other thrombocytopenias). • Thrombosis: arterial or venous, including limb DVT, PE, MI, stroke, skin necrosis at injection sites. • Other causes ruled out. The 4T score (each item 0–2 points; total 0–8) stratifies clinical probability. Score ≥6 = high probability. Confirmation requires anti-PF4 ELISA plus a functional assay (serotonin release SRA — gold standard). Management: (1) Stop ALL heparin immediately — UFH, LMWH, heparin flushes (incl. line locks), heparin-coated catheters. (2) Start a non-heparin anticoagulant: argatroban (direct thrombin inhibitor, hepatic clearance — preferred in renal impairment), bivalirudin, or fondaparinux (Xa inhibitor; off-label but commonly used). (3) Send anti-PF4 antibody and confirmatory test. (4) Do NOT give platelets (would feed thrombosis); transfuse only for major bleed. (5) Avoid warfarin until platelets recover (>150 K) — early warfarin can cause venous limb gangrene. (6) Document HIT diagnosis prominently — lifetime heparin avoidance, allergy band. Continuing or increasing heparin (options 1, 3) feeds the disease; switching UFH to LMWH (option 4) does NOT help — HIT is a class effect (cross-reactivity ~85%). ## Related questions - [A nurse is reviewing the morning lab results for an adult client receiving warfarin for at…](https://mymerci.kr/pages/nclex_q.php?qn_id=360515&lang=en) - [A client is admitted to the emergency department after ingesting an unknown amount of acet…](https://mymerci.kr/pages/nclex_q.php?qn_id=362720&lang=en) - [A client with chronic heart failure is prescribed metoprolol 25 mg orally twice daily. Bef…](https://mymerci.kr/pages/nclex_q.php?qn_id=362756&lang=en) - [A 28-year-old client with type 1 diabetes receives regular insulin 6 units and NPH insulin…](https://mymerci.kr/pages/nclex_q.php?qn_id=362792&lang=en) - [A client receives IV vancomycin 1 g every 12 hours for MRSA bacteremia. 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