C5 Isobars

Description: 
The C5 isobar test is a second line screening test which is indicated when an increased C5 carnitine result is obtained by Newborn Screening Programme Centre. Four different isobars (isovalerylcarnitine, pivaloylcarnitine, valerylcarnitine and 2-methylbutyrylcarnitine) can contribute to C5 increase. The aim of the test is to identify which compound is present in the sample to aid interpretation of the screening result.
Reference range: 

Qualitative analysis only - results are reported as an interpretive comment.

Department: 
Biochemical Sciences Department
Location: 
St Thomas' Hospital
Sample type and Volume required: 
Capillary blood spotted onto a Newborn Screening blood spot card (Guthrie card). Minimum one spot of 7 mm diameter.
Call in advance: 
Yes
Turnaround time: 
Same day from SE Thames NBS lab, five working days for samples from external NBS laboratories.
Special sample instructions: 

Allow to dry at room temperature prior to packaging. 

Criteria for acceptance / rejections of sample
Storage and transport: 
Send via first class post. Samples should be received within the laboratory within 14 days of collection.
Contacts:
Inherited Metabolic Diseases Unit at St Thomas' Hospital
0207 188 9652
St Thomas' Hospital
North Wing - 4th Floor
London
SE1 7EH
For clinical advice or interpretation of results, please contact the laboratory in the first instance.
Laboratory: 
Inherited Metabolic Disease Laboratory at St Thomas'

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Last updated: 24/09/2021