Pathology Handbook

Very long chain fatty acids (VLCFA)


VLCFA, peroxisomal function tests

Clinical Indications

Plasma very long chain fatty acids (especially C26:0) are elevated in peroxisomal disorders such as Adrenoleukodystrophy, Refsum disease and Zellweger Syndrome. They may present with profound neurological and metabolic problems in infancy or neurological and adrenal problems in childhood and adult life.

Phytanic acid may also be raised in Refsum's disease.

Test Includes

C22, C24, C26, C24/C22 and C26/C22 ratios, phytanate and pristanate

Request Form 

Request on ICE


On request. 

Specific Criteria

Requested by Consultants in paediatrics or if agreed with Consultant Biochemist

Patient Preparation

It is important fasting samples are collected in children over 18 months old

Turnaround Time

Approximately 3 weeks


Plasma collected into lithium heparin tube


Minimum volume 0.2 mL


Vacutainer green top


Samples should be transported to laboratory immediately.

Causes for Rejection

Unlabelled sample
Not meeting specific criteria for analysis. 
Delay in sample reaching laboratory
Patient not fasting. 

Reference Range

Reference ranges are age-related

See laboratory report