FSH

Blood Sciences Test

Specimen

Serum

Units

iu/L

Reference Range

Female

Follicular phase 3.5 – 12.5 iu/L
Mid-cycle peak 4.7 – 22.0 iu/L
Menopausal 25.0 – 135.0 iu/L

Male

1.5 – 12.4 iu/L

Test Usage

Specimens are ideally collected during the Follicular phase except when timing ovulation.

Release of both hormones is episodic and can lead to biological variation throughout the day.

In the male, FSH stimulates spermatogenesis whereas LH, stimulates interstitial cells to release testosterone.

Applications

Identifying the menopause. The FSH rises from a base-line of less than 8 to above 28. FSH rises relatively more than LH.

Ovarian or testicular failure. Both FSH and LH rise to menopausal levels.

Gonadal failure can be primary as in agenesis, dysgenesis, Klinefelter’s or Turners syndromes. Or it can be secondary as in premature menopause, oophorectomy, or testicular damage.

Identifying day of ovulation in fertility control.

Hypopituitarism . LH and FSH are not usually undetectable in hypopituitarism but low or inappropriately normal values in patients with low oestradiol (women) or low testosterone (men) are suggestive. Mid-range or high values can help exclude hyopituitarism.

Polycystic ovary syndrome. LH is often raised relative to FSH with an LH/FSH ratio >2.5

These cyclical changes will not, of course, be found in women on oral contraceptives which suppress LH and FSH below the reference range.

Turn around Time:

1 day

Availability

Local test

Can be added on to an existing request up to 4 days following sample receipt

Specimen Labelling Procedure