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HelpTest Code LAB2896 Carnitine Free and Total, blood
Clinical System Name
Carnitine Free and Total, Blood
Synonyms
CarnFreTo
Sample Requirements
Specimen: Whole Blood
Container(s): Dark Green/Sodium Heparin, Lt. Green/ Lithium Heparin, Gold SST, Red
Preferred Vol: 1.0 mL
Minimum Vol: 0.5 mL
Note: EDTA plasma or Serum is also acceptable. Test can be done on dried blood spots (3 full spots on a newborn screening card), however, plasma is the preferred sample type, especially for follow up testing of an abnormal newborn screen..
Processing Instructions
Reject due to: Gross Hemolysis
Spin: Y
Aliquot: Y
Temp: -20 C
Storage location: CPA -20C Freezer, Biochemical Genetics Box
Off-site collection: Freeze and ship heparinized plasma or serum (preferred sample type), EDTA plasma acceptable. Blood spotted on newborn screening filter card should be shipped at room temperature.
Stability
| Temperature | Time |
|---|---|
| Room temp | 5 days |
| Refrigerated | 5 days |
| Frozen (-20C) (serum/plasma) | 1 month |
Availability
| STAT | Performed | TAT |
|---|---|---|
| N | M, Th | 3-7 days |
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
82379
Methodology
Method: Tandem mass spectrometry
Analytical Volume: 0.2 mL
Limitations:
Description
Measurement of free, acylcarnitine and total carnitine by ESI-MS/MS using stable isotope internal standards
Free carnitine is included within the Acylcarnitine report (LAB429); if both are ordered, the carnitine will be cancelled as a duplicate and only the Acylcarnitine reported.
Requisition
Biochemical Genetics Requisition
On the requisition include clinical information needed for appropriate interpretation. (Age, gender, drug therapy, and family history)
Clinical Utility
Carnitine is quantitated for the purpose of follow-up in patients with organic acidurias or fatty acid oxidation disorders who may become carnitine deficient, those on valproate or other drugs that bind to and deplete carnitine, those on hyperalimentation or dialysis, and those on supplemental carnitine.
Reference Ranges
| mcmol/L | < 1 wk | 1 wk - 1 mo | > 1 mo |
| Total Carnitine | 17 - 41 | 20 - 59 | 29 - 84 |
| Free Carnitine | 10 - 33 | 16 - 57 | 18 - 65 |
| Acylcarnitine | 3 - 24 | 4 - 24 | 4 - 28 |
| Acyl/Free ratio | 0.2 - 1.4 | 0.2 - 0.5 | 0.1 - 0.8 |