--- Query Results ---

Program:Genetics and Genomics
Test Name:Homocysteine - Total, urine (G&G South ACH)
Test Code:THCYS-U
Performing Site: Alberta Children's Hospital
Performing Dept:Biochemical Genetics
Availability:Test is performed on a monthly basis.
TAT:30 days
Preferred Tube/Container:Random specimen: plain urine container
Specimen Requirements:Collect 5-10 mL random urine sample.
Min. Sample Required:1.0 mL urine
Specimen Processing:1.  If specimen is transferred to secondary aliquot tube or container, write "urine" on label.
2.  Freeze.
Specimen Handling:Transport frozen samples on ice. Samples must not thaw during transport.
Additional Information:Samples will be rejected if:
  • Aliquot tube received thawed
  • Sample type not written on aliquot tube label
    Requisition/Form:Submit request using Biochemical Genetics Laboratory Requisition.
    Please ensure all required information, including patient's clinical history/indication, is provided on the requisition.
    Order Restrictions:This test is considered specialty testing; this test will be cancelled if sufficient clinical justification is not provided.
    Indications:This test is for the investigation of a primary disorder associated with methionine or cobalamin metabolism based on clinical presentation, or when an initial cystinuria/homocystinuria (a.k.a., nitroprusside) screen was found to be abnormal and there was insufficient sample for reflexive testing.
    This test should not be ordered for the investigation of nutritional vitamin B12 deficiency, nor for assessing carrier status of the common methylene tetrahydrofolate reductase (MTHFR) polymorphisms.
    Method:Total homocysteine is detected following reduction using liquid chromatography, electrospray-ionization tandem mass spectrometry (LS-MS/MS) with a deuterium-labelled internal standard.
    Method Details:Total homocysteine can be elevated in the following enzyme deficiencies:

    Disorders Detectable by Elevated Plasma Total Homocysteine:
  • cystathionine beta-synthase deficiency (classical homocystinuria)
  • methylenetetrahydrofolate reductase deficiency (MTHFR)
  • methionine synthase deficiency
  • Cobalamin (Cbl) C, D, E, F, G, J and X deficiencies
  • transcobalamin II deficiency
  • S-adenosylhomocysteine hydrolase (SAHH) deficiency
  • glycine N-methyltransferase (GNMT) deficiency
  • methionine adenosyltransferase (MAT) I/III deficiency
  • adenosine kinase (ADK) deficiency

    Other causes of Elevated Plasma Total Homocysteine:
  • nutritional vitamin B12 deficiency
  • folate deficiency
  • nutritional B6 deficiency
    Reference Interval:
    Urine Total Homocysteine (<1 year)0.8 - 5.0 mmol/mol Cr
    Urine Total Homocysteine (>1 year)0.1 - 3.6 mmol/mol Cr
    Comments:Contact ACH Biochemical Genetics Laboratory (403-955-7379) for priority turn-around.
    Last Updated On:Thursday, August 31, 2017
    Date of Last Review:Jan 2 2018 12:00AM