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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 is a hormone produced by the pituitary gland that plays a key role in reproductive health, including egg development in women and sperm production in men.

Quick summary

["FSH helps regulate your menstrual cycle and fertility, and its levels can indicate reproductive health status."]

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

Key facts at a glance

LOINC
110650-9
Short code
FSH Msmt SerPl
Synonyms
FSH Msmt SerPl
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 Follicle-Stimulating Hormone (FSH)?

FSH is a hormone essential for reproductive function. In women, it stimulates the growth of follicles in the ovaries, which eventually release an egg. In men, FSH supports sperm production in the testes. Your body produces FSH in the pituitary gland, a small organ at the base of your brain.

Why Might You Need This Test?

Doctors may order an FSH test to evaluate fertility issues, assess hormonal imbalances, diagnose conditions like polycystic ovary syndrome (PCOS), or check for hormonal disorders in both men and women. It can also help monitor conditions like premature ovarian insufficiency or hypogonadism.

Who Typically Needs an FSH Test?

Common reasons include unexplained infertility, irregular menstrual cycles in women, low sperm counts in men, or symptoms of hormonal imbalances such as missed periods, early menopause, or low libido. Your doctor may also recommend it during pregnancy planning or to monitor certain chronic conditions.

What to Expect Before the Test

No special preparation is usually needed, but your doctor may advise fasting for 8–12 hours before the blood draw if the test is part of a larger panel. On the day of the test, avoid strenuous activity or excessive stress, as these can sometimes affect hormone levels temporarily.

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 Does FSH Level Affect My Health?
Elevated FSH levels can signal early menopause, ovarian dysfunction, or conditions like PCOS. In men, high FSH may indicate low testosterone or reduced sperm production. Low FSH levels might suggest pituitary gland issues or other hormonal deficiencies. Your doctor will interpret results in the context of your symptoms and medical history.
What Are Common Causes of Abnormal FSH Levels?
Abnormal FSH levels can result from genetic conditions, tumors affecting the pituitary gland, thyroid disorders, or chronic illnesses like kidney disease. In women, conditions like premature ovarian failure or autoimmune disorders can also alter FSH levels.
What If My FSH Test Results Are Out of Range?
If your results are outside the expected range, your doctor will discuss potential next steps, such as additional tests (e.g., LH, estradiol, or testosterone) or further evaluation of your reproductive or hormonal health. Follow-up may include lifestyle adjustments, medical treatments, or monitoring over time.
  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