Neurology & psychiatry

5-Hydroxytryptophan (CSF) unit converter

Serotonin precursor in CSF (AADC deficiency)

Also known as: 5-HTP CSF, CSF 5-HTP, 5-HTP im Liquor

Converter

Enter a value in any unit and all other units fill in.

ng/mL nmol/L µg/dL ng/dL ng/L pmol/L

Worked example

5 nmol/L (middle of the reference range) = 1.1 ng/mL

Conversion formulas

ng/mL	ng/mL = nmol/L × 0.2202	nmol/L = ng/mL × 4.541
µg/dL	µg/dL = nmol/L × 0.02202	nmol/L = µg/dL × 45.41
ng/dL	ng/dL = nmol/L × 22.02	nmol/L = ng/dL × 0.04541
ng/L	ng/L = nmol/L × 220.2	nmol/L = ng/L × 0.004541
pmol/L	pmol/L = nmol/L × 1000	nmol/L = pmol/L × 0.001

Good to know

5-Hydroxytryptophan (5-HTP) in cerebrospinal fluid is reported in nmol/L or in ng/mL.

ng/mL × 4.54 = nmol/L (exact factor 4.541).
Intake of 5-HTP supplements raises the CSF value.

Reference range

Unit	Adults
ng/mL	0 – 2.202
nmol/L	0 – 10
µg/dL	0 – 0.2202
ng/dL	0 – 220.2
ng/L	0 – 2202
pmol/L	0 – 10 000

Source: Cerebrospinal fluid neurotransmitters, pterins, folates and amino acids in paediatric-onset epilepsies, Children 2025 (age-related reference ranges of the authors' laboratory, PMC) · Last reviewed: 2026-10-19

Note from the source: 0-10 nmol/L at all ages (age-related ranges of the authors' laboratory); raised in aromatic L-amino acid decarboxylase deficiency and after 5-HTP intake. 1 ng/mL = 4.54 nmol/L

Frequently asked questions

How do I convert 5-Hydroxytryptophan (CSF) from nmol/L to ng/mL?

ng/mL = nmol/L × 0.2202. In the other direction: nmol/L = ng/mL × 4.541.

What is the reference range of 5-Hydroxytryptophan (CSF)?

For adults the range is 0 – 10 nmol/L (Cerebrospinal fluid neurotransmitters, pterins, folates and amino acids in paediatric-onset epilepsies, Children 2025 (age-related reference ranges of the authors' laboratory, PMC)). Reference ranges differ between laboratories and partly by sex and age; use the range printed on your lab report.

Which units are used for 5-Hydroxytryptophan (CSF)?

Common units are ng/mL, nmol/L, µg/dL, ng/dL, ng/L, pmol/L.