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L-Dopa Plasma Concentration (24-Hour Urine Collection)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of L-DOPA, a chemical produced in the body that helps regulate movement and mood, over a 24-hour period in your urine.

Quick summary

["L-DOPA levels can help diagnose or monitor conditions affecting movement and dopamine production."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
73309-7
Short code
L-Dopa ind plt IgG SerPl Ql FC
Synonyms
L-Dopa ind plt IgG SerPl Ql FC
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
82784
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you have symptoms like movement problems (such as tremors or stiffness), mood changes, or if you’re being treated for conditions like Parkinson’s disease or dopamine-related disorders. It helps track how well your body is processing L-DOPA.

What to Expect Before the Test

You’ll need to collect all urine for 24 hours in a special container. Drink plenty of fluids but avoid foods or supplements that might interfere with the test. Your doctor will provide clear instructions.

What Happens During the Test

No blood draw is needed—this is a urine test. Your sample is sent to a lab for analysis, and results are compared to reference ranges for your condition.

What the Results Mean

Results may show how much L-DOPA your body absorbs or converts. Abnormal levels could indicate issues with dopamine production, metabolism, or how your body responds to treatment.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

What does a normal result mean?
A normal result doesn’t mean your body is functioning perfectly—it simply indicates that your L-DOPA levels fall within expected ranges for your condition. Your doctor will interpret results in the context of your symptoms and treatment.
Can diet or medications affect this test?
Yes, certain foods, supplements, or medications (like dopamine agonists) can influence L-DOPA levels. Your doctor will guide you on avoiding or adjusting these to get accurate results.
How often should I get this test?
Your doctor will determine the frequency based on your condition and treatment plan. Regular monitoring helps track progress and adjust care as needed.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy