Newcastle Laboratories

Intermediary metabolites, blood and CSF

Clinical Background:

The concurrent measurement of the major body fuels (glucose, lactate, pyruvate, alanine, 3-hydroxybutyrate, glycerol and non-estifried fatty acids [NEFA]) is an effective way to investigate metabol...

The concurrent measurement of the major body fuels (glucose, lactate, pyruvate, alanine, 3-hydroxybutyrate, glycerol and non-estifried fatty acids [NEFA]) is an effective way to investigate metabolic disturbances such as hypoglycaemia. For example, the causes of non-ketotic hypoglycaemia in childhood (B-oxidation disorders and hyperinsulinism) can be differentiated. Thus in the case of a B-oxidation failed ketogenesis occurs in the presence of high NEFA whereas hyperinsulinism results in attenuated lipolysis and thus both 3-hydroxybutyrate and NEFA are low.

Hypoglycaemia resulting from impaired gluconeogensis is usually characterised by an appropriate ketogenic response but increased concentrations of gluconeogenic precursors (lactate, pyruvate and alanine). It is recommended that investigations include measurement of insulin, c-peptide and the counter-regulatory hormones.

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Test Details

  • Discipline:

    Biochemistry

    Biochemistry

  • Minimum Volume Adult:

    0.5 – 1 ml blood or CSF

    0.5 – 1 ml blood or CSF

  • Minimum Volume Paediatric:

    0.5 – 1 ml blood or CSF

    0.5 – 1 ml blood or CSF

  • Special Requirement:

    Samples must be collected in tubes containing perchloric acid (PCA).

    NUTH users - obtain PCA tubes from Paediatric Biochemistry section or ward fridge.

    Send on ice (tube in plastic bag to keep dry)...

    Samples must be collected in tubes containing perchloric acid (PCA).

    NUTH users - obtain PCA tubes from Paediatric Biochemistry section or ward fridge.

    Send on ice (tube in plastic bag to keep dry).

    Collect in early a.m. after at least 12h fast.  For hypoglycaemia investigation collect during an episode or a controlled fast.  Please collect sample prior to administration of glucose.

    Referral laboratories – please contact the lab for information on sample collection.

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  • Transport Requirements:

    Frozen (preferably on solid CO2)

    Frozen (preferably on solid CO2)

  • Interpretation:

    Reports are issued with a full interpretation and suggestions for follow-up investigation.

    Reports are issued with a full interpretation and suggestions for follow-up investigation.

  • Reference Ranges:

    Intermediary metabolites profile includes lactate, pyruvate, glucose, glycerol, alanine, beta-hydroxy butyrate and NEFA

    Reported with an interpretative comment.

    Intermediary metabolites profile includes lactate, pyruvate, glucose, glycerol, alanine, beta-hydroxy butyrate and NEFA

    Reported with an interpretative comment.

  • Other Info:

    Hypoglycaemia is usually defined as a blood glucose of less than 2.6 mmol/l but the blood glucose of some healthy children will fall below this if they are fasted for more than 20 hours, so the res...

    Hypoglycaemia is usually defined as a blood glucose of less than 2.6 mmol/l but the blood glucose of some healthy children will fall below this if they are fasted for more than 20 hours, so the response to fasting requires careful assessment.
    Any child who becomes symptomatic or whose blood glucose falls below 2.6 mmol/l by 16 hours is abnormal until proved otherwise. The blood lactate should remain less than 2 mmol/l throughout the fast, but if the child is struggling the concentrations are likely to be falsely elevated. Raised lactate levels at the time of hypoglycaemia suggest a defect of gluconeogenesis. Acetoacetate and 3-hydroxybutyrate concentrations rise during the fast and are related to the free fatty acid concentration. Low ketone body levels relative to the NEFA concentration suggest a fatty acid oxidation disorder. Hyperinsulinism should be suspected if the plasma insulin level exceeds 5 IU/l at the time of hypoglycaemia with low circulating levels of non-esterified fatty acids (NEFA) and ketones.
    If the plasma cortisol level is less than 400 mmol/l at the time of hypoglycaemia, adrenocortical insufficiency should be considered.
    Glucagon stimulation tests are needed if hypopituitarism is suspected: in normal children, growth hormone levels are not always elevated at the time of fasting hypoglycaemia.

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  • Routine Contact Name:

    Duty Biochemist

  • Routine Telephone:

    Freeman: 0191 282 9719

    RVI: 0191 282 9719

    Freeman: 0191 282 9719

    RVI: 0191 282 9719

  • Routine Email:

  • Specialist Test:

    Yes

    Yes

  • Specialist Contact Name:

    Metabolic Clinical Scientist

    Metabolic Clinical Scientist

  • Specialist Telephone:

    0191 282 9685 (Consultant Clinical Scientist)

    0191 282 0334 (Metabolic Laboratory)

    0191 282 9685 (Consultant Clinical Scientist)

    0191 282 0334 (Metabolic Laboratory)

  • Specialist Email:

Availability:

Available during full access hours
Assayed weekly
Site of analysis: RVI

Turn Around:

Within 1 week

Send To:

Department of Blood Sciences

Level 3
Leazes Wing
Royal Victoria Infirmary
Queen Victoria Road
Newcastle upon Tyne
NE1 4LP

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