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FSH (Follicle Stimulating Hormone) in Serum

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

This blood test measures the levels of follicle-stimulating hormone, a key hormone involved in regulating reproductive function in both men and women.

Quick summary

["FSH helps track fertility and hormone balance."]

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

Key facts at a glance

LOINC
25640-4
Short code
FSH 1.5h p 100 ug LRH IV SerPl-aCnc
Synonyms
FSH 1.5h p 100 ug LRH IV 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 Is This Test Done?

Your doctor may order an FSH test to evaluate fertility issues, assess hormone imbalances, diagnose conditions like polycystic ovary syndrome (PCOS), or monitor hormone therapy. It can also help determine if you’re approaching menopause or perimenopause.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the draw if your lab requires it. Wear a comfortable shirt for easy access to your arm.

How the Test Works

A small sample of blood is taken 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 doctors compare your hormone levels to typical ranges for your age and sex. High or low FSH can signal underlying health concerns, but interpretation depends on your medical history and symptoms.

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 plays a central role in reproductive health. In women, elevated FSH often signals early menopause or ovarian dysfunction, while low levels may indicate hormonal deficiencies. In men, it helps assess sperm production and testosterone function.

Short name

FSH Serum

Frequently asked questions

What causes abnormal FSH levels?
Abnormal FSH can result from conditions like pituitary disorders, ovarian cysts, premature ovarian failure, or genetic factors. Lifestyle factors (e.g., obesity, smoking) may also influence hormone balance.
How often should I get this test?
Your doctor will determine the frequency based on your symptoms, medical history, or treatment plan. Follow-up tests may be scheduled every 3–12 months if monitoring reproductive health or hormone therapy.
Can lifestyle changes affect FSH levels?
Yes—diet, exercise, stress, and weight can impact hormone production. Maintaining a balanced diet, managing stress, and avoiding smoking may help support healthy hormone function.
  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