Homocysteinemia, Indications and Interpretation

What sample is needed for Homocysteine (Homocysteinemia)?

1. This test can be done on the patient’s serum.
2. Separate serum immediately and freeze within one hour.
3. This can be detected in the urine.

What are the precautions for Homocysteine (Homocysteinemia)?

1. 10 to 12 hours of fasting before the test is required.
2. Patients with renal diseases will have an increased level of homocysteine. This is due to the poor excretion of the protein.
3. The patient with a low intake of Vit. B has increased the level of homocysteine.
4. Men have a higher level than women.
5. Smoking will lead to a higher level of homocysteine.
6. Drugs increase Homocysteine levels like methotrexate, nitrous oxide, phenytoin, and carbamazepine.
7. Oral contraceptives influence the level.

What are the indications to measure  Homocysteine (Homocysteinemia)?

1. To diagnose homocystinuria.
   1. This is done to measure the plasma level of homocysteine (homocysteinemia).
   2. It is done to find genetic or acquired homocysteine excess.
2. The patients are at risk of developing folate deficiency and cobalamin.
3. In patients with unexplained anemia.
4. Recurrent spontaneous abortion.
5. Delayed development or failure to survive in infants.
6. In cases of peripheral neuropathy and myelopathy.
7. For the evaluation of cardiovascular disease.
8. Where will you advise homocysteine to be estimated?
   1. This can be used for the surveillance of malnutrition.
   2. In vegetarians who are not taking a supplement of B12.
   3. In patients above the age of 75 years.
   4. The patient is on the treatment of antiepileptic drugs and methotrexate.
   5. Increased risk for pregnancy complications and neural tube defect.
9. What will happen in a patient with coronary disease?
   1. Patients <40 years of age with a history of cardiovascular disease exclude homocysteinemia.
   2. Patients at high risk for cardiovascular disease should be tested every 3 to 5 years.
10. How often should homocysteine be tested?
    1. This may be measured every 3 to 5 years.
    2. In newborns at the age of 3 to 5 days.

 How will you define Homocteinemia?

1. Homocteinemia/Homocystinuria is caused by the genetic deficiency of methionine synthase, which is present on chromosome 1q43.
2. Homocysteine is the reduced (sulfhydryl) form, while homocystine is the oxidized (disulfide) form of homologous cysteine and cystine.
3. This may also be caused by inherited disorders in folate or cobalamine metabolism.
4. The above terms refer to the combined pool of homocystine and homocysteine and their mixed disulfides.

How will you describe the pathophysiology of  Homocysteinemia?

1. Homocysteine is a sulfur-containing amino acid.
   1. It is formed during the metabolism of methionine.
   2. It requires folic acid as a cofactor.
   3. It may be catabolized to cysteine in the presence of Vitamin B as a cofactor.

Homocysteine (Homocysteinemia): Methionine and Homocysteine metabolism (Homocystenemia)

2. Homocysteinemia is the elevation of homocysteine in the blood.
3. Vitamins are the cofactor involved in the metabolism of Methionine to homocysteine.
   1.  Folic acid acts as a cofactor.
   2. The common non-genetic elevated level of homocysteine is caused by a deficiency of B6, B12, or folate.
   3. Homocysteine does not accumulate in the blood because it is unstable in an aqueous solution; when it is in excess, it will undergo oxidation and give rise to homocystine.

Homocysteine (Homocysteinemia): Homocysteine conversion to Homocystine (Homocystenemia)

What are the causes of Homocysteinemia?

1. Genetic predisposition.
2. Nutritional and environmental factors.
3. Specific medications.
4. Amino acids are naturally made products, which are the building blocks of all the proteins in the body.
5. Homocysteine is an intermediate amino acid formed during the metabolism of methionine.
6. So, homocysteine blood level is helpful in diagnosing deficiency of these vitamins.
7. Homocysteine levels may be increased in megaloblastic anemia patients before other abnormal tests are found.
8. Homocysteine may be used as an early indicator of these patients, and treatment can be started early.

Homocysteine (Homocysteinemia): Homocysteine metabolism (Homocystenemia)

What are the complications of Homocysteinemia?

1. Increased atherosclerosis by causing damage to the endothelial lining.
   1. Increased LDL deposition.
   2. Increase vascular smooth muscle growth.
2. Increased risk for vascular diseases.
3. Increased risk of venous thrombosis.
4. Increased risk for pregnancy complications and neural tube defects.
5. The patient with increased homocysteine has 5 times more risk of stroke, dementia, and Alzheimer’s disease.
6. Increased homocysteine level is also a risk factor for osteoporotic fractures in older men and women.
7. Increasing the homocysteine level will increase the risk of coronary artery disease and thrombosis risk.
8. Homocysteinemia >15 µmol/L leads to:
   1. Increased atherosclerosis.
      1. Although lipoproteins are normal.
      2. In the absence of other risk factors.
9. Some researchers believe these patients may be treated with vitamins B6, B12, and folate.
10. Affected children suffer from homocystinuria and have very premature increased atherosclerosis at an early age.

What are the clinical Presentations of  Homocysteinemia?

1. Increased Homocysteine is associated with the following:
   1. Various vascular and cardiovascular diseases.
   2. The birth defects.
   3. Complications in the pregnancy.
   4. Psychiatric disorders.
   5. Mental impairment in older adults.

What is the Normal Homocysteine?

Homocysteine

Source 2

• Fasting level = 4 to 17 µmol/L  (0.54 to 2.3 mg/L).

Source 4

•  4 to 17 µmol/L

Another source

•  Serum = 13 to 18  µmol/L
• Plasma = 10 to 15 = µmol/L
• Children = 3.7 to 10.3 µmol/L

Urine 

• Negative

How will you interpret Homocysteinemia?

• Normal less than 15 µmol/L
  1. Moderate increase = 5 to 30 µmol/L.
  2. Intermediate increase = 30 to 100 µmol/L.
  3. Severe disease = >100 µmol/L.
• There is an unexplained thromboembolic phenomenon.
  1. Homocysteinemia is a risk factor for premature arteriosclerosis of the coronary, cerebral, and peripheral vessels.
  2. Homocysteinemia is a risk factor for thromboembolic disease.
  3. Gradient response to the risk of thrombosis = Risk for thrombosis = <7 µmol/L.
     1. No risk = 9.0 µmol/L.
     2. Low risk = 14.0 µmol/L.
     3. Moderate risk = >14.0 µmol/L.

Where will you see Homocysteine?

1. Folic acid deficiency.
2. Vit.B12 deficiency.
3. Cardiovascular diseases.
4. Cerebrovascular diseases.
5. Peripheral vascular diseases.
6. Malnutrition.
7. Homocystinuria.

What are the recommendations for the raised homocysteine?

1. To exclude homocystinuria, total homocysteine is recommended in patients with cardiovascular disease <40 years.
2. To know the prognosis and mortality, total homocysteine is measured in patients with cardiovascular disease.
3. Cardiovascular disease patients with >15 µmol/L are in high-risk groups. These patients need all kinds of precautions to prevent cardiovascular attacks. Such patients need a healthy life.
4. Risk for thrombosis = <7 µmol/L.
5. Keep a low level of methionine, around 20 to 150 µmol/L, with a low methionine diet and pyridoxine therapy.
6. >30 µmol/L is a prognostic factor for mortality and cardiovascular disease attack.

What are the conditions under which Homocysteine is raised?

1. Few drugs like methotrexate, phenytoin, and theophylline.
2. Hypothyroidism.
3. In pregnancy, to screen for folate deficiency.

What are the differences between homocysteinemia and homocystinuria?

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