What does it mean to have high homocysteine levels?

Homocysteine is an amino acid produced when proteins are broken down. A high homocysteine level, also called hyperhomocysteinemia, can contribute to arterial damage and blood clots in your blood vessels.

High homocysteine levels usually indicate a deficiency in vitamin B-12 or folate.

A normal level of homocysteine in the blood is less than 15 micromoles per liter (mcmol/L) of blood. Higher levels of homocysteine are split into three main categories:

  • Moderate: 15-30 mcmol/L
  • Intermediate: 30-100 mcmol/L
  • Severe: greater than 100 mcmol/L

Elevated homocysteine symptoms

Hyperhomocysteinemia itself usually does not cause any symptoms in adults, though it can in children. Symptoms can also vary from one person to the next and be subtle.

Doctors may order a homocysteine test if they suspect you have a vitamin deficiency, and if you begin exhibiting symptoms of a vitamin deficiency.

Symptoms of a vitamin B-12 deficiency include:

  • pale skin
  • weakness
  • fatigue
  • tingling sensations (like pins and needles) in the hands, arms, legs, or feet
  • dizziness
  • mouth sores
  • mood changes

Symptoms of a folate deficiency are often subtle and are similar to those of a B-12 deficiency. These include:

  • fatigue
  • mouth sores
  • tongue swelling
  • growth problems

Symptoms of vitamin deficiency anemia overlap with those of B-12 and folate deficiencies, also causing additional symptoms:

  • fatigue
  • muscle weakness and unsteady movements
  • pale or yellowish skin
  • personality changes
  • shortness of breath or dizziness
  • irregular heartbeat
  • numbness or tingling in hands and feet
  • mental confusion or forgetfulness
  • weight loss

Causes of high homocysteine levels

Many factors contribute to high homocysteine levels. If you have a folate or B vitamin deficiency, you may develop hyperhomocysteinemia.

Other risk factors include:


If you test positive for elevated homocysteine levels, you could be at an increased risk of developing a number of health issues. Some common conditions associated with high homocysteine are:


Your doctor can perform a simple blood test to measure how much is in your bloodstream. This can also detect if you’ve developed a vitamin deficiency or identify the cause of unexplained blood clots.

Your doctor may require you to fast a few hours before the test. Certain medications or vitamin supplements can affect your results. Talk to your doctor about any medications you’ve been taking prior to this test.

Results are usually available within 24 hours.

Treating hyperhomocysteinemia

Once diagnosed, you may have to change your diet to lower your homocysteine levels. If you have a vitamin deficiency, you can increase your vitamin B intake and folic acid by eating folate-rich foods such as green vegetables, orange juice, and beans.

In some cases, doctors may prescribe daily vitamin supplements.

Once you begin treatment, you should have your homocysteine levels rechecked within two months. If your homocysteine levels are still high after taking these supplements, your doctor may prescribe medications with higher levels of folic acid and vitamin B.

If you have developed hyperhomocysteinemia as a symptom from other health conditions, treatment will focus on the underlying condition.


While it’s possible to lower high homocysteine levels, there’s not enough research to determine whether treatment can prevent associated diseases.

If diagnosed with hyperhomocysteinemia, discuss your treatment options with your doctor. Proper treatment and some lifestyle changes can help to ensure a higher quality of life.