|Test Code||FATAC / POX-M|
|Test||FATTY ACID PROFILE, PEROXISOMAL (C22-C26), SERUM|
|Methodology||Gas Chromatography / Mass Spectrometry (GC-MS), Stable Isotope Dilution Analysis|
|Description||Plasma very long chain fatty acids represent the most important biochemical markers of peroxisomal disorders, particularly to diagnose X-linked adrenoleukodystrophy (X-ALD).
A profile of elevated phytanic acid, low normal pristanic acid, and normal VLCFA is consistent with a diagnosis of Refsum's disease, phytanic acid oxidase deficiency. Serum phytanic acid concentration may also be increased in disorders of peroxisomal biogenesis and should be considered in the differential diagnosis of peroxisomal disorders.
|Specimen||Draw blood in a plain, red-top tube or serum gel tube following an overnight (12 - 24 hour) fast. Patient must not consume any alcohol for 24 hours before the specimen is drawn. Spin down and send 0.5 mL (minimum: 0.2 mL) of serum FROZEN in plastic vial on dry ice.
|Reference Values||Age-dependent reference values for pristanic acid and phytanic acid are listed in "Fatty Acid Reference Values.'
C24:0 / C22:0 RATIO
C26:0 / C22:0 RATIO
|Analytic Time||3 Days|
|Day(s) Test Set Up||Monday through Friday|