Acylcarnitine Profile (Plasma): Results Explained

Tetradecanoylcarnitine (C14)

Other names: Tetradecanoylc., C14, TETRADECANOYLCARNITINE, C14

Optimal result: 0 – 0.03 umol/L

By Healthmatters Editorial Team

Peer-reviewed sources

Elevated Tetradecanoylcarnitine (C14) indicates a buildup of long-chain fatty acid intermediates, suggesting incomplete beta-oxidation or reduced mitochondrial capacity to process long-chain fats. High C14 can occur during metabolic stress, fasting, mitochondrial dysfunction, or impaired carnitine transport. Significant or persistent elevation may point to a block in long-chain fatty acid oxidation or, more rarely, an inherited metabolic disorder such as VLCAD or CPT-II deficiency. Assessing other long-chain acylcarnitines helps clarify where the metabolic bottleneck may be occurring.

Low Tetradecanoylcarnitine (C14) may reflect reduced long-chain fatty acid availability, low dietary fat intake, decreased carnitine levels, or reduced mitochondrial beta-oxidation activity. Low results can also occur with low metabolic demand or prolonged low-energy states.

Tetradecanoylcarnitine (C14) is a long-chain acylcarnitine formed during the transport and breakdown of 14-carbon fatty acids in the mitochondria. It reflects how efficiently long-chain fats are activated, transported, and oxidized for energy. C14 levels provide insight into mitochondrial beta-oxidation, metabolic flexibility, and the body’s capacity to use fat as a fuel source.

Tetradecanoylcarnitine (C14) is part of the acylcarnitine profile used to evaluate long-chain fatty acid metabolism. When long-chain fatty acids enter cells, they must be converted into acylcarnitines like C14 to move into the mitochondria for beta-oxidation. Because of this, C14 serves as a functional marker of mitochondrial fuel processing and the balance between fatty acid supply, activation, and oxidation.

C14 levels may shift in response to metabolic demand, fasting, exercise, diet composition, and mitochondrial efficiency. Elevated or decreased values can reflect how well the mitochondria are processing long-chain lipids, making C14 useful in assessing metabolic flexibility and possible disruptions in energy metabolism. In rare cases, abnormal C14 levels can also appear in inherited fatty acid oxidation disorders or carnitine transport defects.

Interpreting C14 alongside related markers—such as C12, C14:1, C16, and C18 acylcarnitines—provides a clearer picture of long-chain fatty acid oxidation and potential metabolic bottlenecks.

Organize and understand all your lab results

Start organizing — $15/mo →

For Health Professionals Healthmatters Pro Multiple clients’ results in one dashboard. See Pro plans →

Tetradecanoylcarnitine (C14)

Every lab result you’ve ever had, charted and explained.

Healthmatters is a tracker for your lab results. Upload a report from any lab, any country — every marker charted and explained.

Start with my report →

Clinical Sources & References

All our content is backed by peer-reviewed studies, academic research, and trusted medical sources. We’re committed to accuracy and transparency — see our editorial policy for details.

Article Review Log

Written by Healthmatters Editorial Team

Organize and understand all your lab results

Start organizing — $15/mo →

For Health Professionals Healthmatters Pro Multiple clients’ results in one dashboard. See Pro plans →

Healthmatters Lifetime Plan

Pay $250. Track your health forever

One payment. No renewals. Yours for life.

10,000+ biomarkers explained · trends over time

See other plans →

Secure checkout via Stripe · GDPR & HIPAA

We accept results from any lab

LabCorp Quest Diagnostics Genova Diagnostics DUTCH Test Doctor's Data Vibrant America ZRT Laboratory Cyrex Labs + any other lab

What members are saying

★★★★★ 10,000+ happy members

★★★★★

"Watching my numbers move over the years — instead of forgetting last time's results — completely changed how I manage my health."

Daniel

Member since 2022

★★★★★

"Living across several countries made keeping my lab results organized a real challenge. Healthmatters brought my results from the USA, Spain, and Germany together — 20 years of history, with long-term trends instead of scattered reports."

Ben

Member since 2021 · tracks across countries

★★★★★

"Standard lab ranges are too wide for how I practice — 'normal' isn't optimal. I set my own bands, so a client sees yellow before a marker goes officially out of range. That's the conversation I want to be having."

Dr. Alexandra

Functional medicine · 6 yrs on Pro