Cardiovascular Medicine Book

Coronary Artery Disease

Hyperlipidemia

Hypertension

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HomocysteineAka: Hyperhomocysteinemia

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  1. See Also
    1. Homocystinuria
    2. Hypercoagulable State
  2. Epidemiology
    1. Elevated in 15-30% of patients with premature CAD
  3. Pathophysiology
    1. Folate needed to convert homocysteine to methionine
    2. May reduce CAD risk by lowering homocysteine levels
    3. Dose response curve: lowest Folate, Highest risk
  4. Causes: Hyperhomocysteinemia
    1. Vitamin Deficiency
      1. Folate Deficiency
      2. Vitamin B6 Deficiency
      3. Vitamin B12 Deficiency
    2. Chronic Disease
      1. Chronic Renal Failure
      2. Hypothyroidism
      3. Psoriasis
      4. Cancer
      5. Tobacco abuse
    3. Medications
      1. Anticonvulsants
      2. Methotrexate
      3. Nitrous Oxide
    4. Homocystinuria (Inherited)
  5. Complications: High homocysteine levels
    1. Coronary Artery Disease
    2. Cerebrovascular Accident
    3. Peripheral Vascular Disease
    4. Deep venous thrombosis
    5. Hypertension
    6. Dementia may also be related
  6. Labs: Protocol for Blood Total Homocysteine concentrations
    1. Step 1: Collect
      1. Draw in tube with anticoagulant
      2. EDTA, Heparin, or Sodium Citrate
    2. Step 2: Process
      1. Spin sample within 30 minutes of collection
      2. Otherwise risk of false elevation from RBCs
    3. Step 3: Storage
      1. Refrigerate up to 2-3 weeks OR
      2. Frozen for 2-3 months
  7. Labs: Homocysteine Level Interpretation
    1. Optimal Homocysteine: <12 umol/L
    2. Borderline Homocysteine: 12-15 umol/L
    3. Hyperhomocysteinemia: >15 umol/L
  8. Management
    1. Homocysteine lowering therapy lowers CAD risk
      1. See Cardiac Risk Management
    2. Measures to lower homocysteine levels
      1. Folic Acid supplementation
      2. Vitamin B12 Supplementation
      3. Vitamin B6 supplementation
      4. References
        1. Schnyder (2002) JAMA 288:973
        2. Rimm (1998) JAMA 279:359
  9. Management: Folate Dosing Protocol
    1. High risk patient with Homocysteine >12 umol/L
      1. Multivitamin (with 400 ug folate) qd AND
      2. Folic Acid 800 ug qd
    2. Recheck Homocysteine Level in 8 weeks: Normal
      1. Continue Multivitamin
      2. Discontinue Folic Acid
      3. Recheck Homocysteine again in 8 weeks
    3. Recheck Homocysteine Level in 8 weeks: >12 umol/L
      1. Continue Multivitamin
      2. Increase Folic Acid to 2 mg qd for 8 weeks
        1. Folic Acid is Safe <5mg/day
      3. Recheck Homocysteine again in 8 weeks
        1. If normal
          1. Continue Multivitamin
          2. Discontinue folate
        2. If still increased
          1. Check Vitamin B6 Level
          2. Increase Folate to 5 mg/day
          3. Assess patient compliance
          4. Test for other causes
  10. References
    1. Fallest-Strobl (1997) Am Fam Physician 56(6):1612
    2. Morrison (1996) JAMA 275:1893

Hyperhomocysteinemia (C0598608)

Definition (MSH)An inborn error of methionone metabolism which produces an excess of homocysteine in the blood. It is often caused by a deficiency of CYSTATHIONINE BETA-SYNTHASE and is a risk factor for coronary vascular disease.
ConceptsDisease or Syndrome (T047)
EnglishHyperhomocysteinemia, Hyperhomocysteinemias
Spanishhiperhomocisteinemia
CreditsDerived from the NIH UMLS (Unified Medical Language System)


Homocysteine cysteine disulfide:Substance Concentration:Point in time:Serum/Plasma:Quantitative (C1315089)

ConceptsClinical Attribute (T201)
EnglishHomocysteine cysteine disulfide:SCnc:Pt:Ser/Plas:Qn, Homocysteine cysteine disulfide:Substance Concentration:Point in time:Serum/Plasma:Quantitative
CreditsDerived from the NIH UMLS (Unified Medical Language System)



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