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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 in your blood. FSH plays a key role in reproductive health, influencing egg development in women and sperm production in men.

Quick summary

["FSH helps regulate your body’s reproductive cycle and hormone balance."]

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

Key facts at a glance

LOINC
16873-2
Short code
FSH 105M p chal SerPl-sCnc
Synonyms
FSH 105M 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 This Test Might Be Ordered

Your healthcare provider may recommend an FSH test if you have symptoms like irregular periods, infertility, low libido, or concerns about hormonal imbalances. It may also be used to check for conditions like polycystic ovary syndrome (PCOS), early menopause, or hormonal disorders in both men and women.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a larger blood draw. Wear comfortable clothing and plan to stay near a testing facility for a short time.

How the Test Works

A small blood sample is taken from a vein in your arm. The sample is sent to a lab, where it is analyzed to measure FSH levels using an immunoassay method, which detects specific proteins in your blood.

What the Results Mean

Results are interpreted based on your age, sex, and medical history. High or low FSH levels can signal underlying health issues, such as hormonal imbalances, ovarian or testicular dysfunction, or conditions affecting fertility.

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 my FSH level indicate?
High FSH levels may suggest early menopause, ovarian reserve depletion, or conditions like PCOS. Low FSH could indicate hypothyroidism, pituitary disorders, or other hormonal imbalances. Always discuss results with your doctor, as they’ll consider your full medical picture.
Can lifestyle changes affect FSH results?
Yes, stress, poor sleep, extreme weight changes, or certain medications (like birth control or thyroid hormone replacements) can influence FSH levels. If you suspect lifestyle factors are at play, talk to your provider about adjustments.
How often should I get this test?
Your doctor will determine the frequency based on your symptoms, medical history, or treatment plan. Some patients may need retesting after changes in health or hormonal treatments, while others may only need it once for diagnosis.
  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