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Paediatric Biochemistry

The laboratory is faced with a number of considerations when dealing with paediatric samples.  These include:

  • Small sample volumes
  • Poor plasma yield
  • Poor quality samples (haemolysed, icteric, tissue fluid dilution)
  • Difficult patient preparation
  • Rapid turnaround time needed
  • Lack of medical history
  • Complex metabolic presentations

In most cases, routine paediatric tests can be requested in a similar manner to adult tests, and do not require particular patient preparation.  Where available, paediatric test results are reported with an age/gender-appropriate reference range.

The laboratory appreciates that collecting specimens from paediatric patients is a challenging task, and will always attempt to utilise samples efficiently.  In cases where sample volume is limited, then it is useful for the clinical team to indicate which tests are most important for patient management.

Repeat requesting must be kept to a minimum.  If repeated requests are required for a specific clinical reason, then this should either be indicated in the clinical details, or the Duty Biochemist should be informed.  This allows repeat requests to be authorised with minimum delay.

Please see the relevant test pages for details on testing:

Metabolic investigations involve complex and extended procedures.  The referral laboratory has extensive experience in analysis and interpretation of results, and may add further investigations based on initial results.  Please ensure that all requests are supplied with sufficient clinical details. This will help the specialist hospital undertaking the analysis to provide a thorough interpretation.

The most common requests for metabolic investigations are listed below.  For any queries regarding sampling requirements for tests not detailed below please contact the Duty Biochemist or the Paediatric Liaison via the Helpdesk.

Please note that the turnaround times for these tests are usually between 14 and 21 days. Some of the enzyme assays can take at least 6 weeks.

Test Comments
Amino Acids (urine) Preferably fasting. Please provide details of drug therapy
Amino Acids (blood)
Acylcarnitines and free carnitine Please send whole blood and blood spots
Organic acids  
Very long chain fatty acids  

For information on more specialised metabolic investigations, please contact the Duty Biochemist for discussion, or see individual test profiles as appropriate.

Samples for CSF neurotransmitter analysis must be frozen in dry ice at the patient’s bedside.  It is vital that the laboratory is given sufficient notice (> 48 hours) to order dry ice and arrange for a Clinical Scientist to attend the procedure.  Samples must be collected in special cryovials, which are available from the Neurometabolic Unit, Queen’s Square, London.  These must be stored at 4 °C prior to use.

The usual request form must be accompanied by an additional Neurotransmitter Request form, which is supplied with the cryovials.

The order of CSF draw is important.  Samples for neurotransmitter analysis should be taken last.  The Clinical Scientist will freeze these samples at the bedside, and transport them to the laboratory.  The remaining samples should be transported via the porters as usual.  Do not send CSF samples in the pneumatic tube system.

Please contact the Duty Biochemist, or see the CSF Neurotransmitters test profile for further information.

The laboratory is happy to facilitate skin and muscle biopsy sampling on a case-by-case basis. It is recommended that both local and referral laboratories (Birmingham Children’s Hospital) are contacted prior to sampling to discuss specific sample requirements for each individual case.

For neonates with ?congenital adrenal hyperplasia, the laboratory will facilitate urgent sample transport and analysis of 17-hydroxyprogesterone at University Hospitals Birmingham. 

Please contact the Duty Biochemist to discuss transport and sampling arrangements.

Please see the relevant test page for SUDI/C investigations