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HelpTest Code LAB8341 Carnitine, Free and Total
Aliases
L-Carnitine
Carnitine, S
Specimen Type
Serum or Plasma:
Green Top -Lithium Heparin (Preferred)
Dark Green Top – Sodium Heparin
Red Top -Plain
Gold Top -SST
Processing Instructions
Green or Gold top-CENTRIFUGE per procedure / Red Top – Clot 60 minutes in upright position
Pipette off plasma or serum into pour off tube
Attach original tube to pour off tube with rubber band
Store and ship sample Frozen on dry ice.
Specimen Volume
Preferred: 3.0 mL (1.0 mL serum/plasma)
Minimum: 0.6 mL (0.2 mL serum/plasma)
Temperature
Frozen (dry ice)
Test/Batch Schedule
Tue and Fri
TAT
5 days
Test Components
Carnitine, Total
Carnitine, Free
Acylcarnitine
AC/FC Ratio
Carnitine
Reference Range
Carnitine, Total15-136 nmol/mL
Carnitine, Free
12-87 nmol/mL
Acylcarnitine
3.0-53.0 nmol/mL
AC/FC Ratio
0.1-1.8
Carnitine
Normal
CPT
82379
Performing Section
Biochemical Genetics
Purpose/Principle
Carnitine is measured by stable isotope dilution/liquid chromatography/tandem mass spectrometry. The carnitine measurement is made in a plasma sample before and after hydrolysis of carnitine esters with sodium hydroxide. The former measurement represents “free” carnitine and the latter represents “total” carnitine. Esters (or “acylcarnitines”) are calculated as the difference between the “total” and “free” levels.