Follicle Stimulating Hormone (FSH)

Clinical Chemistry

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Description

Human follicle stimulating hormone ( FSH ) is a glycoprotein of approximately 30,000 daltons which, like luteinising hormone ( LH ), human chorionic gonadotrophin ( hCG ) and thyroid stimulating hormone ( TSH, thyrotrophin ), consists of two noncovalently associated subunits designated alpha and beta. The a subunit of FSH contains 92 amino acids and is identical to the a subunits of LH, hCG, and TSH. The b subunit of FSH is unique and confers its immunological and functional specificity. FSH and LH control growth and reproductive activities of the gonadal tissues. FSH promotes follicular development in the ovary and gametogenesis in the testis. The cells of the anterior pituitary secrete both FSH and LH in a pulsatile manner in response to gonadotrophin releasing hormone ( LHRH or GnRH ) from the hypothalamus. Release of both FSH and LH from the pituitary is under negative feedback control by the gonads ( or exogenous oestrogens as in oral contraceptive use ). In mature females, FSH stimulates development of the ovarian follicles. Circulating FSH levels vary throughout the menstrual cycle in response to oestradiol and progesterone. A small, but significant increase in circulating FSH accompanies the mid-cycle LH surge. Circulating levels of FSH decline in the luteal phase in response to oestradiol and progesterone production by the developing corpus luteum.

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Indications

Males and females: investigation of infertility and assessment of pituitary function. Females: menstrual irregularities and to diagnose menopause only in women aged 40-45 years with symptoms and in women under 40 years in whom menopause is suspected. Hormone tests ( including FSH ) should not routinely be used to diagnose menopause in women over 45 years ( NICE guidelines NG23, 2015 ). Males: investigation of gonadal failure ( low testosterone ).

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Sample Type

Serum, SST, Gel, minimum 2mL ( 1mL separated serum )

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Reference Range

Reference ranges are provided on the report. Alternatively, please contact the laboratory for current ranges.

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Turnaround Time

Within 3 days

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Testing Frequency

As required

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