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FSH (Follicle Stimulating Hormone) – Serum/plasma concentration

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 hormone production and reproductive function in both men and women.

Quick summary

["FSH helps guide fertility and hormone balance, often checked when evaluating reproductive health."]

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

Key facts at a glance

LOINC
21277-9
Short code
FSH 2h p GnRH SerPl-aCnc
Synonyms
FSH 2h p GnRH 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

Why This Test Might Be Ordered

Your healthcare provider may recommend an FSH test to assess fertility, diagnose hormonal imbalances, or evaluate conditions like polycystic ovary syndrome (PCOS), early menopause, or low sperm production in men.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before drawing blood. If you’re taking medications that affect hormones, let your provider know.

How the Test Works

A small sample of blood is drawn from a vein in your arm. The sample is sent to a lab where it’s analyzed to measure FSH levels using an immunoassay method.

What the Results Mean

Results help determine whether hormone levels are too high or too low, which can influence fertility, menstrual cycles, or other reproductive health concerns.

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

How long does it take to get my FSH test results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your provider will contact you once they’re ready.
Can lifestyle changes affect my FSH test results?
Stress, extreme weight loss, or certain medications may temporarily influence hormone levels. Avoiding alcohol and smoking before testing can help ensure accurate results.
Is fasting required for this test?
No fasting is required, but some labs may recommend it for consistency. Always follow your provider’s specific instructions.
  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