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HelpTest Code LAB3544 Very Long Chain Fatty Acid
Clinical System Name
Very Long Chain Fatty Acid
Synonyms
Peroxisomal Biogenesis Defects
Peroxisomal Disorders
VLCFA
Sample Requirements
Specimen: Whole Blood
Container(s): Lavender/EDTA
Preferred Vol: 2.0 mL
Minimum Vol: 1.0 mL (0.5 mL for infants)
Note: Fasting sample preferred. Serum and heparnized plasma are also acceptable but not preferred.
Processing Instructions
Reject due to: gross lipemia, gross hemolysis
Spin:Y
Aliquot:Y
Temp:-20 C
Storage location: CPA Freezer, BCG Box
Off-site collection: Spin and freeze aliquoted plasma. Ship frozen.
Stability
| Temperature | Time |
|---|---|
| Room temp | ≤ 2 hr |
| Refrigerated | 24 hrs |
| Frozen (Preferred) | 3 months |
Availability
| STAT | Performed | TAT |
|---|---|---|
| N | Weekly | 1 week |
Contact the Biochemical Genetics Lab for requests outside of stated availability (206)987-2216.
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Biochemical Genetics
Phone Number: 206-987-2216
CPT Codes
82726
Methodology
Method: GC/MS with stable isotope internal standards
Analytical Volume: 0.2 mL
Limitations:
Additional Information: Includes C26, C22, C24, phytanic acid, pristanic acid, C26/C24 and C24/C22
Non-fasting, hemolyzed samples, or samples from patients on a ketogenic diet can cause false elevations in VLCFA and phytanic acid. Ketogenic diets high in milk fat rather than vegetable fat cause higher phytanic acid levels. Consumption of peanuts (particularly peanut butter) may cause elevations of very long chain fatty acids. Recommend avoiding peanut consumption for 12 hours before sample collection.
Reference Range
| C26 | 0.05 - 0.41 mcg/mL |
| C22 | 9 - 33 mcg/mL |
| C24 | 7 - 28 mcg/mL |
| Phytanic | < 3.0 mcg/mL |
| Pristanic | < 0.3 mcg/mL |
| C26/C22 |
< 0.02 |
| C24/C22 | 0.6 - 1.1 |
Description
A comprehensive profile that includes C26, C22, C24, C26/C22, C24/C22, phytanic, and pristanic acid analysis, performed by GC/MS.
Requisition
Biochemical Genetics Requisition
On the requisition include clinical information needed for appropriate interpretation. (Age, gender, diet (e.g. TPN therapy), drug therapy and family history)
Clinical Utility
For evaluation of disorders of peroxisomal biogenesis or peroxisomal metabolism.
|
|
Zellweger |
infantile Refsum |
RCDP |
nALD |
X- ALD |
Refsum Classic Adult |
Single enzyme; D-Bifunctinal protein |
Single enzyme; Acyl-CoA Oxidase |
|---|---|---|---|---|---|---|---|---|
|
Inheritance |
Aut. Rec. |
Aut. Rec. |
Aut. Rec. |
Aut. Rec. |
X-linked |
Aut. Rec. |
||
|
C26/C22 |
Elevated |
Elevated |
Normal |
Elevated |
Elevated |
Normal |
Elevated |
Elevated |
|
Phytanic |
Elevated* |
Elevated |
Normal/Elevated (type I ) |
Elevated |
Normal |
N/ Elevated |
N to increased |
Normal |
|
Plasmalogens |
Decreased |
Decreased |
Decreased (all forms) |
Decreased |
Normal |
Normal |
Normal |
|
|
Pipecolic Acid |
Elevated |
Elevated |
Elevated |
Normal |
Normal |
|||
|
Pristanic Acid |
Elevated* |
Elevated |
Normal/Dec |
Elevated |
Normal |
Normal |
N to elevated |
Normal |
*Phytanic and pristanic can be normal in a neonate with a peroxisomal biogenesis disorder (PBD) since accumulation of branched chain fatty acids occurs through dietary intake. Newborns with PBD may also not have reduced plasmalogens.