II. Epidemiology
- Elevated in 15-30% of patients with premature CAD
III. Pathophysiology
- Folate needed to convert Homocysteine to Methionine
- Initially thought that lowering Homocysteine levels decreased Cardiovascular Risk
- Dose response curve: lowest Folate, Highest risk
- Now Folate supplementation not thought to impact Cardiovascular Risk
IV. Causes: Hyperhomocysteinemia
-
Vitamin Deficiency
- Folate Deficiency
- Vitamin B6 Deficiency
- Vitamin B12 Deficiency
- Chronic Disease
- Medications
- Anticonvulsants
- Methotrexate
- Nitrous Oxide
- Homocystinuria (Inherited)
V. Complications: High Homocysteine levels
- Coronary Artery Disease
- Cerebrovascular Accident
- Peripheral Vascular Disease
- Deep venous thrombosis
- Hypertension
- Dementia may also be related
VI. Labs: Protocol for Blood Total Homocysteine concentrations
- Step 1: Collect
- Draw in tube with Anticoagulant
- EDTA, Heparin, or Sodium Citrate
- Step 2: Process
- Spin sample within 30 minutes of collection
- Otherwise risk of false elevation from RBCs
- Step 3: Storage
- Refrigerate up to 2-3 weeks OR
- Frozen for 2-3 months
VII. Labs: Homocysteine Level Interpretation
- Optimal Homocysteine: <12 umol/L
- Borderline Homocysteine: 12-15 umol/L
- Hyperhomocysteinemia: >15 umol/L
VIII. Management
- Homocysteine lowering therapy lowers CAD risk
- Measures to lower Homocysteine levels
- Folic Acid supplementation
- Vitamin B12 Supplementation
- Vitamin B6 supplementation
- References
IX. Management: Folate Dosing Protocol
- High risk patient with Homocysteine >12 umol/L
- Multivitamin (with 400 ug Folate) qd AND
- Folic Acid 800 ug qd
- Recheck Homocysteine Level in 8 weeks: Normal
- Continue Multivitamin
- Discontinue Folic Acid
- Recheck Homocysteine again in 8 weeks
- Recheck Homocysteine Level in 8 weeks: >12 umol/L
- Continue Multivitamin
- Increase Folic Acid to 2 mg qd for 8 weeks
- Folic Acid is Safe <5mg/day
- Recheck Homocysteine again in 8 weeks
- If normal
- Continue Multivitamin
- Discontinue Folate
- If still increased
- Check Vitamin B6 Level
- Increase Folate to 5 mg/day
- Assess patient compliance
- Test for other causes
- If normal
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Related Studies
| Definition (MSH) | Condition in which the plasma levels of homocysteine and related metabolites are elevated (>13.9 μmol/l). Hyperhomocysteinemia can be familial or acquired. Development of the acquired hyperhomocysteinemia is mostly associated with vitamins B and/or folate deficiency (e.g., PERNICIOUS ANEMIA, vitamin malabsorption). Familial hyperhomocysteinemia often results in a more severe elevation of total homocysteine and excretion into the urine, resulting in HOMOCYSTINURIA. Hyperhomocysteinemia is a risk factor for cardiovascular and neurodegenerative diseases, osteoporotic fractures and complications during pregnancy. |
| Definition (NCI) | A serious metabolic condition caused by mutations in the MTHFR gene, medications, or nutritional deficiency. It results in increased levels of homocysteine in the blood. Patients with this condition are at an increased risk for recurrent blood clots formation and cardiovascular accidents. |
| Concepts | Disease or Syndrome (T047) |
| MSH | D020138 |
| SnomedCT | 419503008 |
| Spanish | hiperhomocisteinemia (trastorno), hiperhomocisteinemia, Hiperhomocistienemia, Hiperhomocisteinemia |
| Japanese | 高ホモシステイン血症, ｺｳﾎﾓｼｽﾃｲﾝｹｯｼｮｳ, ｺｳﾎﾓｼｽﾃｲﾝｹﾂｼｮｳ |
| Swedish | Hyperhomocysteinemi |
| Czech | hyperhomocysteinémie, Hyperhomocysteinemie |
| Finnish | Hyperhomokysteinemia |
| Russian | GIPERGOMOTSISTEINEMIIA, ГИПЕРГОМОЦИСТЕИНЕМИЯ |
| English | Hyperhomocysteinemias, Hyperhomocysteinemia [Disease/Finding], hyperhomocysteinaemia, hyperhomocysteinemia, Hyperhomocysteinaemia, Hyperhomocysteinemia, Hyperhomocysteinemia (disorder) |
| Croatian | HIPERHOMOCISTEINEMIJA |
| Portuguese | Hiper-Homocisteinemia, Hiperhomocisteinemia, Hiper-homocisteinemia |
| Polish | Hiperhomocysteinemia |
| Hungarian | Hyperhomocysteinaemia |
| Norwegian | Hyperhomocysteinemi |
| Dutch | hyperhomocysteïnemie, Homocysteïnemie, hyper-, Hyperhomocysteïnemie |
| German | Hyperhomocysteinaemie, Hyperhomozystinämie |
| French | Hyperhomocystéinémie |
| Italian | Iperomocisteinemia |
Ontology: Homocysteine cysteine disulfide:SCnc:Pt:Ser/Plas:Qn (C1315089)
| Concepts | Clinical Attribute (T201) |
| LNC | 32615-7 |
| English | Homocysteine cysteine disulfide [Moles/volume] in Serum or Plasma, Hycs-Cys diS SerPl-sCnc, Homocysteine cysteine disulfide:SCnc:Pt:Ser/Plas:Qn, Homocysteine cysteine disulfide:Substance Concentration:Point in time:Serum/Plasma:Quantitative |
