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Revision Questions: Blood & Electrolytes (Preview)

Sample Questions

  1. What is the difference between low molecular weight heparins (LMWHs) and heparin?
  2. What is heparin-induced thrombocytopenia and what may it lead to?
  3. A patient is admitted to hospital with DVT. The doctor plans to give her warfarin. What are your concerns with starting warfarin?
  4. What is target INR?
  5. Provide some counselling points for warfarin.

Sample Answers

  1. LMWHs: longer half life (3-6 hours), given once daily, no monitoring required except platelets, more expensive, risk of heparin-induced thrombocytopenia is lower. Heparin: cheaper, requires 2-3 daily injections, less effective than LMWH in high risk situations.
  2. Thrombocytopenia is the development of a low platelet count due to the administration of heparin, an anticoagulant. It may occur in <1% of patients in short term use. This will result in bleeding, stroke and/or death.
  3. Warfarin takes several days to achieve full anticoagulant effect. With the initiation of warfarin, heparin is also given together until the anticoagulant effect of warfarin is established. This usually takes 5-6 days including at least 2 days with the INR in the therapeutic range. Stop heparin when INR is within range and stable.
  4. 2-3 for all indications except heart valves (seek specialist advice).
  5. Warfarin counselling:
    • Take tablets at about the same time every day; record your dose on a calendar and mark the day off immediately after taking a dose.
    • Always take the same brand of tablets. The two available brands are not interchangeable.
    • Keep your intake of vitamin K constant. Vitamin K is found in certain foods such as green vegetables and may inhibit the effects of warfarin.
    • Avoid excessive alcohol consumption; 12 standard drinks per day maximum
    • Avoid drinking large amounts of cranberry juice as this may increase the effects of warfarin.
    • Warfarin interacts with many medicines. Always tell your doctor and pharmacist that you are taking this medicine before starting or stopping any other medication, vitamin supplement, herbal or OTC product.
    • Regular INR testing is recommended. Obtain the result before the next dose so any adjustments can be made. Extra blood tests may be necessary during serious illness.
    • Seek immediate medical attention if you notice bruising, bleeding, pink, red or dark brown urine, or red or black stools.

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