Carnitine blood test
Quick answer: A carnitine test measures carnitine, a substance that helps the body turn fat into energy. Doctors order it to look for carnitine deficiency, for example in some metabolic disorders, muscle weakness, dialysis or certain medicines.
- SampleBlood
- TakesAbout 5 minutes
- Before the testYour doctor may ask you to fast; follow the instructions given.
How the test is done
- 1You may be asked to fast before the test
- 2The skin over a vein is cleaned
- 3A needle draws blood into a tube
- 4The lab measures free and total carnitine
What your results can mean
Reading your report
Normal ranges differ between labs and by age and sex, so discuss your result with your doctor.
If the result is outside the usual range
A low level can be seen with some inherited metabolic disorders, long-term dialysis, poor nutrition or certain seizure medicines such as valproate. Low carnitine can cause muscle weakness and low energy.
Who usually has this test
Babies and children with suspected metabolic disorders, people on dialysis, and people on long-term valproate with weakness or tiredness.
Risks and aftercare
You can go about your day after the test; the needle site may bruise slightly.
Names and options
Also called: serum carnitine, L-carnitine
Listed by the hospital as
- CARNITINE, SERUM
Questions about this test
What is the difference between free and total carnitine?
Free carnitine is not attached to other molecules, while total includes both free and bound forms. The balance between them helps doctors spot certain disorders.
Can medicines lower carnitine?
Yes. Valproate, a seizure medicine, is a well-known cause. Do not stop it without your doctor's advice.
Should I take carnitine supplements if my level is low?
Only if your doctor recommends them. The right treatment depends on the cause of the low level.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.