Newcastle Laboratories

Aspartate aminotransferase, serum

Clinical Background:

AST is an intracellular enzyme present in both cytoplasm and mitochondria. It is widely distributed throughout the body’s tissues, with the greatest amounts in cardiac muscle, liver, skeletal muscl...

AST is an intracellular enzyme present in both cytoplasm and mitochondria. It is widely distributed throughout the body’s tissues, with the greatest amounts in cardiac muscle, liver, skeletal muscle and the kidneys. It is a key enzyme in gluconeogenesis. AST is used to identify tissue damage e.g. arising from damage to cardiac muscle (typically ischaemic in origin), damage to skeletal muscle (e.g. rhabdomyolysis) and liver cell inflammation or necrosis. The major disadvantage of AST as an indicator of tissue damage is its lack of specificity to any one tissue. Alanine aminotransferase (ALT) is to be preferred as an indicator of liver cell damage. AST present in the plasma is presumed to be derived from the normal turnover of tissue cells; increased quantities are found in tissue damage (particularly hepatic and cardiac and skeletal muscle damage)

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Test Details

  • Discipline:

    Biochemistry

    Biochemistry

  • Specimen Container Adult:

    Serum

    Serum

  • Specimen Container Paediatric:

    Serum

    Serum

  • Minimum Volume Adult:

    1 mL blood

    1 mL blood

  • Minimum Volume Paediatric:

    0.5 mL blood

    0.5 mL blood

  • Sample Stability:

    Unseparated sample: 3 days

    Separated sample:

    - 4 days at 15-25C

    - 7 days at 4ºC

    - 3 months at -20C

    Unseparated sample: 3 days

    Separated sample:

    - 4 days at 15-25C

    - 7 days at 4ºC

    - 3 months at -20C

  • Add On Test:

    Add-on available up to 7 days

    All urgent add ons via telephone on 0191 282 4766, and must be confirmed via email to the appropriate email address

    RVIadditions.Laboratory@nuth.nhs.uk (internal)

    tnu-...

    Add-on available up to 7 days

    All urgent add ons via telephone on 0191 282 4766, and must be confirmed via email to the appropriate email address

    RVIadditions.Laboratory@nuth.nhs.uk (internal)

    tnu-tr.bloodsciencesadditions@nhs.net (external)

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  • Interpretation:

    The most common cause of an isolated increase in AST activity
    is alcohol‐related or non‐alcoholic fatty liver disease. For any value, a high
    alcohol intake, diabetes and hypertriglyceridaemia (al...

    The most common cause of an isolated increase in AST activity
    is alcohol‐related or non‐alcoholic fatty liver disease. For any value, a high
    alcohol intake, diabetes and hypertriglyceridaemia (all of which can cause
    fatty liver) should be excluded; if present, these should be managed
    appropriately before repeating the test.
    For increases ≤2x ULN, and other LFTs normal, repeat in 1–2 months
    If repeat value ≤3x ULN, further investigation is required
    Values >3x ULN further investigation is appropriate without repeat
    testing irrespective of results of other LFTs.

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  • Reference Ranges:

    All ages: 0 - 40 U/L

    All ages: 0 - 40 U/L

  • Factors Affecting Result:

    Haemolysis.
    In very rare cases gammopathy, in particular type IgM (Waldenström’s macroglobulinemia), may cause unreliable results.
    Isoniazid can cause artificially low AST results at therapeutic co...

    Haemolysis.
    In very rare cases gammopathy, in particular type IgM (Waldenström’s macroglobulinemia), may cause unreliable results.
    Isoniazid can cause artificially low AST results at therapeutic concentrations.
    Cyanokit (hydroxocobalamin) at therapeutic levels causes significantly lower results.

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  • Other Info:

    Plasma- Lithium Heparin also acceptable

    Plasma- Lithium Heparin also acceptable

  • Routine Contact Name:

    Duty Biochemist

  • Routine Telephone:

    Freeman: 0191 244 8889
    RVI: 0191 282 9719

    Freeman: 0191 244 8889
    RVI: 0191 282 9719

  • Routine Email:

    - For external users: TNU-Tr.duty.biochemist@nhs.net

    - For Trust users: DutyBiochemist@nuth.nhs.uk

Availability:

All times
All sites

Turn Around:

Urgent: within 1 hour

Non-urgent: within 4 hours

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