What is the role of lab testing in the diagnosis of homocysteinemia?

Updated: Jul 27, 2018
  • Author: Pitchaiah Mandava, MD, PhD; Chief Editor: Helmi L Lutsep, MD  more...
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Laboratory studies may be considered in patients who present with symptoms of acute stroke in the absence of traditional risk factors such as hypertension, smoking, and diabetes. Nutritional factors, environmental toxins, or medical conditions may worsen an inherent homocysteinemia. No consensus exists on the timing of the test with respect to an acute event.

Whether a methionine challenge should be used for testing is not clear at this juncture. The methionine challenge test may be more appropriate if a deficiency is suspected in the transsulfuration pathway.

Specimens for total and free homocystine measurement must be handled and processed in a specific way; they must be put on ice and spun within 1 hour. Whether the specifications are always followed by all laboratories or medical offices is unclear.

The risk for vascular disease is graded with respect to the level of homocysteine; however, no threshold abnormal value is accepted widely. If homocysteinemia is determined by a test, then tests for deficiency in folic acid, vitamin B-12, and pyridoxine also may be performed.

Genetic abnormalities are reported on chromosome 1 pertaining to methylene tetrahydrofolate reductase (MTHFR); however, the mere presence of this abnormality may not confer a risk for vascular disease.

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