C16:1OH 3-hydroxyhexadecenoylcarnitine

This test measures the level of C16:1OH, also called 3-hydroxyhexadecenoylcarnitine, in your blood. C16:1OH is one of the long-chain acylcarnitines formed when the body breaks down fats for energy. Laboratories detect it using tandem mass spectrometry as part of an acylcarnitine profile.

C16:1OH is especially useful in evaluating how your cells handle long-chain fatty acids. It is commonly included in newborn screening and in follow-up testing when a fatty acid oxidation condition is suspected.

Abnormal levels of C16:1OH can point to problems using long-chain fats for energy, such as long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency or mitochondrial trifunctional protein deficiency. These conditions can lead to low blood sugar, muscle symptoms, heart involvement, or liver stress, especially during fasting or illness.

Clinicians use this result together with other acylcarnitines, clinical history, and additional laboratory tests to decide on next steps. Finding a pattern that suggests a fatty acid oxidation disorder can guide urgent dietary changes and confirmatory testing, which may reduce the risk of metabolic crises.

Your result is interpreted using age-appropriate reference intervals and by looking at patterns across related acylcarnitines. A single out-of-range result does not confirm a diagnosis. If your level is higher than expected, your clinician may order a repeat sample, a full acylcarnitine profile, organic acids, urine acylglycines, and genetic testing to clarify the cause.

If you or your child has symptoms such as poor feeding, lethargy, vomiting, muscle pain, dark urine, or episodes during illness, share this information with your care team, since it helps interpret the result. Even if the value is within the expected range, your clinician may continue evaluation if there is strong clinical concern, because some conditions show changes only during stress or fasting.