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FSH (Follicle Stimulating Hormone) in Serum/Plasma

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

This test measures the amount of follicle-stimulating hormone in your blood. FSH plays a key role in regulating the menstrual cycle in women and sperm production in men.

Quick summary

["FSH helps balance reproductive hormones and supports fertility."]

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

Key facts at a glance

LOINC
12666-4
Short code
FSH sp4 p chal SerPl-sCnc
Synonyms
FSH sp4 p chal SerPl-sCnc
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

Why Is This Test Done?

Doctors may order an FSH test to evaluate fertility issues, check for hormonal imbalances, diagnose conditions like early menopause or polycystic ovary syndrome (PCOS), or assess hormone levels in men with low testosterone or unexplained infertility.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it’s drawn early in the morning. Avoid strenuous activity or excessive stress on the day of the test. If you’re on hormonal medications, let your healthcare provider know.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but it’s usually over quickly. The blood sample is sent to a lab for analysis.

What Are the Results Mean?

Results are interpreted based on your age, sex, and medical history. High or low FSH levels can indicate underlying health conditions. Your doctor will discuss the results with you in the context of your overall health.

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.

◆Associated findings1

Short name

FSH Level

Frequently asked questions

### What Does an FSH Test Measure?
An FSH test measures the concentration of follicle-stimulating hormone in your blood. This hormone helps control the production of eggs in women and sperm in men.
### Why Might My Doctor Order This Test?
Your doctor may order an FSH test to investigate fertility problems, check for hormonal imbalances, diagnose conditions like early menopause, or evaluate reproductive health in both men and women.
### What Are Common Causes of Abnormal FSH Levels?
Abnormal FSH levels can result from conditions like polycystic ovary syndrome (PCOS), premature ovarian insufficiency, pituitary tumors, or genetic disorders affecting hormone regulation. Always discuss symptoms and test results with your healthcare provider.
  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