Skip to content

Soy Isoflavone Concentration (24-Hour Urinary)

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

This test measures the amount of soy-derived isoflavones, naturally occurring plant compounds found in soy products, over a 24-hour period in your urine.

Quick summary

["Understanding your soy isoflavone exposure may help assess dietary intake or potential effects on hormone levels."]

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

Key facts at a glance

LOINC
64649-7
Short code
Herb natural soy ERT current PhenX
Synonyms
Herb natural soy ERT current PhenX
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
phenx
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 Might Be Ordered

Your healthcare provider may recommend this test if you consume soy products regularly (e.g., tofu, soy milk) and want to monitor your exposure. It could also be part of research studies evaluating soy’s effects on health, such as hormone balance or cardiovascular function.

What to Expect Before the Test

You’ll need to collect all urine for 24 hours in a special container. Drink plenty of water to help flush out isoflavones naturally. Avoid soy supplements or high-soy foods during this period if instructed.

How the Test Works

Your urine sample is analyzed using a sensitive method (likely liquid chromatography or immunoassay) to detect isoflavones, which are broken down into smaller forms (e.g., equol, daidzein, genistein) that appear in urine.

What the Results Mean

Results show the total amount of soy isoflavones excreted in urine. Higher values may indicate higher dietary intake, while lower values could suggest reduced consumption or metabolic differences (e.g., equol producers vs. non-producers).

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

24-Hour Soy Isoflavone Urine

Frequently asked questions

What causes soy isoflavone levels to vary?
Soy isoflavone levels depend on diet (e.g., soy-rich foods, supplements), metabolism (e.g., whether you produce equol), hydration, and whether you follow specific dietary restrictions during testing. Genetics and age may also play a role.
How long does it take to get results?
Results typically arrive within 1–2 weeks after lab processing, depending on your healthcare provider’s lab turnaround time.
Can I eat soy products during the test?
If instructed, avoid soy products (e.g., tofu, soy milk) or supplements for the 24-hour period to get an accurate measurement. Follow your provider’s guidance to ensure reliable results.
  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