FSH

Alternative names 
Follicle stimulating hormone

Definition
An FSH test measures the amount of FSH (a hormone of the reproductive system) in the blood.

How the test is performed

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. A bandage may be applied to the puncture site if there is any continued bleeding.

How to prepare for the test
Adults:
If you are a female in the reproductive years, your health care provider may want you to obtain the blood test on certain days of your menstrual cycle.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:

     
  • Infant test or procedure preparation (birth to 1 year)  
  • Toddler test or procedure preparation (1 to 3 years)  
  • Preschooler test or procedure preparation (3 to 6 years)  
  • Schoolage test or procedure preparation (6 to 12 years)  
  • Adolescent test or procedure preparation (12 to 18 years)

How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed
This test may be performed when certain reproductive or pituitary disorders are suspected.

FSH is a hormone secreted from the anterior pituitary gland. In the woman, FSH stimulates production of ovarian follicles (eggs) and estradiol (another reproductive hormone) during the first half of the menstrual cycle. In the man, FSH stimulates production of sperm in the testicular tubules.

Normal Values

     
  • Male: 4 to 25 IU/L  
  • Female:       o Premenopausal: 5 to 30 IU/L       o Midcycle peak: 10 to 60 IU/L       o Pregnancy: low to undetectable       o Postmenopausal: Greater than 30 IU/L

Note: IU/L = international units per liter.

What abnormal results mean
Disorders that may be associated with abnormal FSH results include:

     
  • Hypopituitarism  
  • Klinefelter’s syndrome  
  • Polycystic ovary disease  
  • Turner’s syndrome  
  • Ovarian failure (ovarian hypofunction)

Additional conditions under which the test may be performed:

     
  • Anovulatory bleeding  
  • Multiple endocrine neoplasia (MEN) I  
  • Ovarian cysts

What the risks are

     
  • Excessive bleeding  
  • Fainting or feeling lightheaded  
  • Hematoma (blood accumulating under the skin)  
  • Infection (a slight risk any time the skin is broken)  
  • Multiple punctures to locate veins

Special considerations
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Johns Hopkins patient information

Last revised: December 8, 2012
by Brenda A. Kuper, M.D.

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