Follicle Stimulating Hormone
What is FSH?
Follicle Stimulating Hormone (FSH) is a hormone associated with reproductive functions such as development of eggs in women and sperms in men. The FSH test is ordered in case of a variety of problems such as difficulty getting pregnant, menstrual irregularities, low sex drive, and early or delayed puberty.
The low levels of FSH may indicate decreased ovulation in women, reduced sperm count in men, problems at the level of the hypothalamus or pituitary gland. High levels of FSH, on the other hand can be indicative of loss of ovarian function and menopause. FSH works closely with another hormone called luteinizing hormone (LH) to control sexual functions. Hence, the LH test is frequently ordered along with the FSH test.
Why is FSH done?
FSH test is done for the following indications:
To evaluate infertility issues in females
To evaluate the function of reproductive organs (ovaries or testicles)
To assess irregular menstrual cycle in women
To diagnose disorders of the pituitary gland or diseases involving the ovaries in women
To evaluate early or delayed sexual maturation (puberty) in children
To evaluate low sperm count in men
To assess hypogonadism or gonadal failure in men
To assess testicular dysfunction in men
What does FSH Measure?
Follicle-stimulating hormone (FSH) is a hormone which is associated with reproduction and the development of eggs in women and sperm in men. This test measures FSH in the blood.
FSH is produced by the pituitary gland, and its production is controlled by a feedback system involving the hypothalamus in the brain, the pituitary gland, and the hormones produced by the ovaries or testicles. The Gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates the pituitary gland to release FSH and luteinizing hormone (LH; another closely-related hormone also involved in reproduction). FSH affects the growth and maturation of egg follicles in the ovaries during the follicular phase of the menstrual cycle. The menstrual cycle is divided into follicular and luteal phases, each phase lasting for 14 days. During the follicular phase, FSH initiates the production of estradiol by the follicle, and the two hormones work together in the further development of the egg follicle. Near the end of the follicular phase, the production of FSH and luteinizing hormone increases. The release of the egg from the ovary (ovulation) occurs shortly after this increased production of hormones. The hormone inhibin as well as estradiol and progesterone help control the amount of FSH released by the pituitary gland. FSH also facilitates the ability of the ovary to respond to LH. At menopause, ovarian function decreases and eventually ceases which results in increased levels of FSH and LH.
In males, the role of FSH is to stimulate the testicles to produce mature sperms and also promotes the production of androgen binding proteins. FSH levels are relatively constant in men after puberty than in women.
In infants and children, FSH levels rise shortly after birth and then fall to very low levels by 6 months in boys and 1-2 years in girls. Concentrations begin to rise again before the beginning of puberty and the development of secondary sexual characteristics.
Disorders affecting the hypothalamus, pituitary, and/or the ovaries or testicles can cause the production of too much or too little FSH, resulting in a variety of conditions such as infertility, abnormal menstrual cycles, or early (precocious) or delayed sexual maturation (puberty).
Interpreting FSH results
Reference range of FSH is age- and gender-specific. As for women, the reference range is menstrual cycle phase-specific.
The reference range for follicle-stimulating hormone (FSH) is as follows (3rd generation immunochemiluminescence assay):
Females reference range:
· Age 0-7 years: <6.7 mIU/mL
· Age 8 years to adult:
· Follicular phase: 3.1-7.9 mIU/mL
· Ovulation peak: 2.3-18.5 mIU/mL
· Luteal phase: 1.4-5.5 mIU/mL
· Postmenopausal: 30.6-106.3 mIU/mL
· Age 0-7 years: <6.7 mIU/mL
· Age 8 years-adult:1.3-19.3 mIU/mL
The reference range may vary from lab to lab*