Tryptophan

An essential amino acid and precursor to serotonin.

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

Tryptophan is an essential amino acid that comes from food. As well as building proteins, it is the starting material for serotonin, a brain chemical linked to mood and sleep, and for niacin (vitamin B3) and melatonin.

Comprehensive Health Check

Reviewed against DGKL reference practice.

Why test this?

Plasma tryptophan is part of a full amino acid profile and reflects protein intake and how your body routes this amino acid. Low levels can reflect poor intake or increased breakdown. It is read in the context of the whole profile.

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	29 to 77 µmol/L

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 tryptophan sits in the usual adult fasting range.
Context for the pathways that make serotonin and niacin.
A piece of the picture of how your body handles dietary protein.

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
StatPearls: Biochemistry, Essential Amino Acids

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.