Should heparin (unfractionated heparin) drip be discontinued in a patient with thrombocytopenia (platelet count of 60)?

YES - Discontinue Heparin Immediately and Start Alternative Anticoagulation

With a platelet count of 60,000/mm³ on heparin drip, you must immediately stop all heparin (including flushes and heparin-coated catheters) and initiate therapeutic-dose non-heparin anticoagulation, even before laboratory confirmation of HIT. 1, 2, 3

Why This Decision is Critical

The FDA label explicitly states: "If the platelet count falls below 100,000/mm³ or if recurrent thrombosis develops, promptly discontinue heparin, evaluate for HIT and HITT, and, if necessary, administer an alternative anticoagulant." 3 Your patient's platelet count of 60,000/mm³ meets this threshold and mandates immediate action.

The thrombotic risk of untreated HIT far exceeds any bleeding risk from therapeutic anticoagulation. 2 Untreated HIT carries a 30-50% risk of developing thrombosis, with potential for limb amputation or death. 2, 4, 5 Simply discontinuing heparin without alternative anticoagulation results in high thrombosis rates, whereas non-heparin anticoagulants reduce this to 12-25%. 2

Immediate Action Steps

1. Stop All Heparin Exposure

• Discontinue the heparin drip immediately 1
• Remove all heparin flushes from IV lines 1, 2
• Replace any heparin-coated catheters 1

2. Calculate 4T Score

Assess pre-test probability of HIT using the 4T score: 2, 6

• Low probability (≤3 points): HIT can be excluded, pursue alternative causes
• Intermediate probability (4-5 points): Stop heparin, start alternative anticoagulation, send HIT antibody testing
• High probability (≥6 points): Stop heparin, start therapeutic-dose alternative anticoagulation immediately—do not wait for test results 2, 6

3. Initiate Alternative Anticoagulation at Therapeutic Doses

Critical: Use therapeutic doses, not prophylactic doses, even without confirmed thrombosis. 2, 6 The hypercoagulable state in HIT requires full anticoagulation to prevent the 30-50% thrombosis risk. 2, 7

Argatroban (Preferred in Most Settings)

• Starting dose: 2 mcg/kg/min as continuous IV infusion 2, 6
• Dose reduction: 0.5 mcg/kg/min if moderate-severe hepatic impairment, heart failure, multiple organ dysfunction, or post-cardiac surgery 2
• Monitoring: Check aPTT 2 hours after starting and maintain at 1.5-3 times baseline 1, 2, 6
• Advantage: Only option for severe renal impairment (CrCl <30 mL/min) as it undergoes hepatic metabolism 2, 6

Bivalirudin (Alternative)

• Starting dose: 0.15-0.25 mg/kg/hour IV infusion 2
• Monitoring: Target aPTT 1.5-2.5 times control 2
• Advantage: Shorter half-life (20-30 minutes) useful for procedures 2
• Contraindication: Severe renal failure (CrCl <30 mL/min) 2, 6

Fondaparinux (For Stable Patients)

• Useful for stable patients without severe renal or hepatic impairment 6
• Does not require specific monitoring 6

Laboratory Testing Strategy

• Send anti-PF4 antibody testing immediately but do not wait for results before starting alternative anticoagulation 1, 2
• If anti-PF4 antibodies are positive with intermediate probability, perform functional test (serotonin release assay or HIPA) to confirm diagnosis 2, 6
• If anti-PF4 antibodies are negative with intermediate probability, HIT is excluded and heparin can be resumed with close monitoring 2

Duration of Alternative Anticoagulation

• Continue until platelet count recovers to at least 150,000/μL 2, 6
• Minimum duration: 4 weeks for isolated HIT without thrombosis 2
• With thrombosis: 3 months minimum 2, 6

Transitioning to Oral Anticoagulation

Do NOT start warfarin during acute HIT. 2, 6 Warfarin can cause venous limb gangrene in acute HIT and should only be initiated after: 2, 7

• Platelet count recovers to >150,000/μL 2, 6
• Patient is therapeutically anticoagulated with alternative agent 6
• Overlap parenteral anticoagulant with warfarin for at least 5 days 2, 6

Direct oral anticoagulants (DOACs) are acceptable alternatives to warfarin for long-term management. 2

Critical Pitfalls to Avoid

• Never use prophylactic doses of alternative anticoagulants—therapeutic doses are mandatory even without thrombosis 2, 6
• Do not give platelet transfusions unless life-threatening bleeding occurs, as they may worsen thrombosis 2, 6
• Do not use low molecular weight heparin (LMWH) as it cross-reacts with HIT antibodies in 80-90% of cases 2
• Do not delay stopping heparin while waiting for antibody test results—the thrombotic risk is immediate and severe 2, 6

Evidence Supporting Therapeutic Anticoagulation

The American College of Chest Physicians demonstrated that argatroban reduces death due to thrombosis by 134 fewer deaths per 1,000 patients (RR 0.12) and new thrombosis by 191 fewer events per 1,000 patients (RR 0.45) compared to discontinuing heparin alone. 1 This moderate-quality evidence with large effect size justifies immediate therapeutic anticoagulation despite the platelet count of 60,000/mm³.