Understanding Your Medical Test: What It Is, Why It's Done, and What the Results Mean
This test measures the level of 3-hydroxyhexanoate, a fatty acid metabolite, in your blood to help diagnose certain metabolic disorders.
{"Measures 3-hydroxyhexanoate, a byproduct of fatty acid breakdown","Used to screen for metabolic disorders like MCAD deficiency","Sample is collected from a blood draw (serum or plasma)","Abnormal results may indicate problems with fat metabolism","Follow your doctor's instructions regarding fasting before the test"}
Key facts at a glance
- LOINC
- 48758-7
- Short code
- 3-OH-C6:0
- Synonyms
- 3OH-hexanoate.free SerPl-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or EDTA plasma tube
- Units
- N/A
- Ref low
- 0.05
- Ref high
- 1.5
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
- CPT
- 82017
- SNOMED
- 122449009
- Specimen volume
- 0.5-1.0 mL serum or plasma minimum
- Stability
- Room temperature: 24-72 hours; Refrigerated (2-8°C): 5-7 days; Frozen (-20°C or below): several weeks to months. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 24–72 hours
- Order
- routine
What exactly is this test, what does it measure or look for in my body, and why do doctors commonly use it?
The 3-hydroxyhexanoate test measures the amount of 3-hydroxyhexanoate (also written as 3-OH-C6:0) in your blood serum or plasma. 3-Hydroxyhexanoate is a type of organic acid that is produced when your body breaks down fatty acids for energy. This test is part of a group of tests called organic acid analysis or acylcarnitine profile testing.
Why might my health care provider recommend this test for me, and what medical conditions or concerns can it help identify?
This test is primarily used to screen for and help diagnose inherited metabolic disorders, particularly medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. In this condition, the body cannot properly break down certain medium-chain fatty acids, leading to a buildup of 3-hydroxyhexanoate and other similar compounds in the blood. The test may also be used to monitor patients already diagnosed with a fatty acid oxidation disorder.
How is this test performed during my visit, what can I expect step by step, and will the procedure cause any discomfort?
A healthcare professional will draw a small sample of blood from a vein in your arm using a needle. The blood will be collected in a special tube and sent to a laboratory for analysis. In some cases, the test may be done as part of newborn screening or during an episode of illness to help identify metabolic problems.
Do I need to do anything special to prepare for this test, such as fasting, adjusting my medications, or avoiding certain foods or drinks?
Your doctor may ask you to fast (not eat or drink anything except water) for a certain period before the blood draw, typically 8-12 hours. This is because eating can temporarily change the levels of fatty acid metabolites in your blood. Follow all instructions provided by your healthcare provider carefully.
What do my test results mean, how will my doctor explain whether they are normal or abnormal, and what happens after I receive them?
Normal results vary by laboratory, but generally, low levels of 3-hydroxyhexanoate are expected in healthy individuals. Elevated levels may indicate a problem with fatty acid metabolism, such as MCAD deficiency or other similar disorders. Your doctor will interpret your results in combination with other test results and your clinical symptoms.
Reference range
Reference range varies by laboratory and methodology. Typically: Newborns 0.1-1.5 umol/L; Children 0.05-0.5 umol/L; Adults <0.3 umol/L. Interpretation should be done in context of clinical presentation and other acylcarnitine profiles.N/A
No special preparation required. For newborn screening, samples are typically collected as heel stick dried blood spots. For plasma/serum testing, random sample collection is acceptable.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The primary clinical significance of the 3-hydroxyhexanoate test is the diagnosis and monitoring of medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, an inherited metabolic disorder. In MCAD deficiency, the body cannot properly convert certain medium-chain fatty acids into energy, leading to accumulation of 3-hydroxyhexanoate and other acylcarnitines in the blood. Without proper diagnosis and treatment, episodes of metabolic crisis can occur, particularly during fasting or illness, which can be life-threatening. Early detection through newborn screening allows for early intervention, including dietary management and avoidance of fasting, which can prevent serious complications.
Frequently asked questions
Is this test painful?
How long does it take to get results?
What happens if my results are abnormal?
Can this test be done on newborns?
Do I need to fast before this test?
Sources
- 1
- 2
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 15, 2026. · Read our editorial policy