Skip to content

Soy Isoflavone Concentration (Serum/Plasma)

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

This test measures the levels of naturally occurring plant compounds called isoflavones found in soy products, which may influence hormone activity in the body.

Quick summary

["Isoflavones in soy may affect hormone balance, but results vary by diet and individual metabolism."]

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

Key facts at a glance

LOINC
64650-5
Short code
Herbal natural soy ERT type PhenX
Synonyms
Herbal natural soy ERT type PhenX
Category
chemistry
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

What Is Soy Isoflavone Testing For?

Isoflavones are phytoestrogens—plant compounds that can mimic estrogen in the body. This test helps assess exposure to soy isoflavones, which may be relevant for research on hormone-related health effects, dietary compliance, or soy product efficacy. Levels can vary widely based on diet, digestion, and metabolism.

How Is This Test Performed?

A blood sample (serum or plasma) is collected and analyzed using a specialized laboratory method, likely high-performance liquid chromatography (HPLC) or a similar technique, to measure isoflavone concentrations. Results are expressed in mass concentration units.

Why Might You Need This Test?

This test may be ordered as part of a study on soy supplementation, hormone balance, or to evaluate exposure to phytoestrogens. It’s not routinely recommended for general health monitoring unless directed by a healthcare provider for specific reasons.

What Do Results Mean?

Higher levels may indicate recent soy consumption, while lower levels could suggest limited exposure. Interpretation depends on clinical context, such as dietary history or research objectives. Reference ranges are not universally standardized for this test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Soy Isoflavones

Frequently asked questions

How often do I need this test?
This test is typically not part of standard health checkups. It may be recommended periodically if you’re participating in a soy-related study, taking soy supplements, or evaluating hormone-related symptoms. Follow your healthcare provider’s guidance for timing and frequency.
What should I do if my results are high or low?
High isoflavone levels may reflect recent soy intake, but they don’t necessarily indicate health risks unless part of a specific study. Low levels could mean reduced soy exposure, but this alone doesn’t diagnose a condition. Discuss results with your provider for personalized advice.
Can diet affect these results?
Yes, soy isoflavone levels are strongly influenced by diet. Soy-containing foods (tofu, tempeh, edamame) and supplements can increase levels. Avoiding soy for a few days before testing may help clarify baseline exposure, but this depends on clinical goals.
  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