Ornithine

An amino acid in the urea cycle that helps clear ammonia.

Last reviewedJune 16, 2026

Plasma

sample type

~5 mL

blood needed

~7 days

results in app

Morning, fasting

best timing

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On this page

Why test Reference ranges What you'll learn What affects it How testing works Sources FAQ

In short

Ornithine is a non-protein amino acid that sits at the centre of the urea cycle, the pathway your body uses to clear ammonia as urea. It is also a precursor of polyamines and proline, which support cell growth and tissue repair.

Comprehensive Health Check

Reviewed against DGKL reference practice.

Why test this?

Plasma ornithine is part of a full amino acid profile and helps show how well the urea cycle is working. High or low levels can point toward specific inherited urea cycle disorders, so it is read together with ammonia, citrulline, arginine and the other amino acids.

What is a normal result?

Aniva reads your result against research-backed ranges, not just the lab's wide normal. The reference shown below is specific to this biomarker.

Adult reference values as used by Aniva. Ranges are guidance and can vary by laboratory and method.

Group	Normal range
Adults	30 to 110 µmol/L

Sources: 2015 Orphanet HHH Syndrome Review

Your Aniva report reads your result against these values together with your age, sex and the rest of your panel.

Ranges are guidance and vary by lab and assay, aligned with DGKL practice. Always read your result against your own lab's reference interval.

What insights will this test give you?

Whether ornithine sits in the usual adult fasting range.
Context for how your body clears nitrogen through the urea cycle.
In some cases, a clue that supports a closer look at a urea cycle pattern.

What can affect this result?

What can skew the result

Results are affected by recent diet, recent protein intake, fasting state and the time of day the sample is taken.

Best interpreted with

Read as part of the full plasma amino acid profile.

How is this tested?

Sample

Plasma

Blood needed

~5 mL

Method

Ion-exchange chromatography or LC-MS/MS

Best timing

Morning, fasting

Sources. The evidence behind this

Mayo Clinic Laboratories: Amino Acids, Quantitative, Plasma

Common questions

Which Aniva panels include this marker?

Amino Acids

These tests assess essential, non-essential, and branched-chain amino acids, plus related metabolites and functional ratios.