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FSH (Follicle Stimulating Hormone) in Serum or Plasma

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

This test measures the amount of follicle-stimulating hormone (FSH) in your blood. FSH plays a key role in regulating reproductive hormones in both men and women.

Quick summary

["FSH helps balance hormone production and supports fertility."]

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

Key facts at a glance

LOINC
32317-0
Short code
FSH BS SerPl-aCnc
Synonyms
FSH BS SerPl-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
3.5
Ref high
12.5
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
83001
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 FSH Used For?

FSH testing is often part of evaluations for infertility, hormone imbalances, or conditions affecting reproductive health. In women, it may help assess ovarian function, especially during perimenopause or menopause. In men, it can check for issues like low testosterone or problems with sperm production.

Who Might Need This Test?

Your doctor may recommend an FSH test if you have symptoms like irregular periods (in women), low libido, or trouble getting pregnant. It’s also used in monitoring conditions like polycystic ovary syndrome (PCOS) or after certain treatments for fertility.

How Is the Test Done?

A blood sample is taken from a vein in your arm. You’ll need to fast for 8–12 hours before the test, unless your doctor instructs otherwise. The sample is sent to a lab for analysis using an immunoassay method to measure FSH levels accurately.

What Do My Results Mean?

Results aren’t interpreted alone—they’re compared to your age, sex, and symptoms. High FSH levels may signal early menopause or ovarian dysfunction, while low levels could indicate hormonal imbalances or other health concerns. Your doctor will discuss findings with you.

Reference range

Follicular: 3.5-12.5 mIU/mLN/A

Specimen: serum

For females: inform if menstrual cycle status. For certain tests, timing within menstrual cycle may matter.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: FSH Levels and Reproductive Health

Short name

FSH Level

Frequently asked questions

Why might my FSH levels be checked during my annual exam?
Your doctor may check FSH levels if they suspect hormonal imbalances, fertility issues, or conditions like early perimenopause. It’s also used to monitor treatments for hormone-related disorders, such as those affecting ovarian or testicular function.
What if my FSH levels are too high or too low?
High FSH levels may indicate declining ovarian reserve (in women) or other reproductive health concerns. Low FSH could suggest pituitary issues, thyroid problems, or other hormonal disturbances. Your doctor will work with you to determine the next steps based on your symptoms and test results.
How often should I get this test?
The frequency depends on your health status and symptoms. If you’re undergoing fertility treatment or managing a chronic condition, your doctor may recommend regular monitoring. Otherwise, it’s often part of routine evaluations for reproductive health.
  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