Follicle-Stimulating Hormone (FSH), Serum
      
Synonyms
  FSH; FSH, Serum; Pituitary Gonadotropin
Specimen
  Serum
Volume
  1 mL
Minimum Volume
  0.3 mL (Note: This volume does not allow for repeat testing.)
Container
  Red-stopper tube or serum gel separator tube
Collection
  If a red-stopper tube is used, transfer separated serum to a plastic transport tube. Avoid hemolysis.
Storage Instructions
  Refrigerate
Causes for Rejection
  Plasma specimen
Reference Interval
  See table.1,2
Age  Male
(mIU/mL) 
Female
(mIU/mL) 
5th d  <0.2-4.6  <0.2-4.6 
2 mo - 3 y  0.2-2.7  1.4-9.2 
4-6 y  0.2-2.7  0.4-6.6 
7-9 y  0.2-2.7  0.4-5.0 
10-11 y  0.4-5.0  Not established 
12-13 y  0.4-6.6  Not established 
14-15 y  0.7-13.2  Not established 
>15 y  1.4-18.1  Follicular: 2.5-10.2 
    Midcycle: 3.4-33.4 
    Luteal: 1.5-9.1 
    Pregnant: <0.2 
    Postmenopausal: 23.0-116.3 
Tanner Stage 
I & II  0.3-4.6  0.7-6.7 
III & IV  1.2-15.4  1.0-7.4 
1.5-6.8  1.0-9.2 
Use
  Excessive FSH and LH are found in hypogonadism, anorchia, gonadal failure,3 complete testicular feminization syndrome, menopause, Klinefelter syndrome, alcoholism, castration. FSH and LH are pituitary products, useful to distinguish primary gonadal failure from secondary (hypothalamic/pituitary) causes of gonadal failure, menstrual disturbances and amenorrhea. Useful in defining menstrual cycle phases in infertility evaluation of women and testicular dysfunction in men. FSH is commonly used with LH, which also is a gonadotropin. Both are low in pituitary or hypothalamic failure. FSH and LH levels are high following menopause.
Limitations
  Secretion of both LH and FSH are pulsatile, in response to the normal intermittent release of gonadotropin releasing hormone (GnRH). In addition, in females both FSH and LH vary over the course of the menstrual cycle, with peaks at time of ovulation. Thus, interpretation of a single determination may be difficult. It has been suggested that samples be obtained at 15-30 minute intervals and equal volumes of serum be pooled to decrease the effect of pulsatile secretion.
Methodology
  Immunochemiluminometric assay (ICMA)
Additional Information
  FSH and LH are glycoprotein pituitary hormones which have unique B-subunits, and a-subunits in common with TSH and hCG. They are under complex regulation by hypothalamic GnRH and by gonadal sex hormones, estrogen and progesterone in females, and testosterone. On the simplest level, FSH and LH are high in conditions in which sex hormones cannot be elaborated, and low in conditions of primary pituitary dysfunction. FSH acts on granulosa cells of the ovary and the Sertoli cells of testis. LH acts on Leydig (interstitial) cells of the gonads. Normally FSH increase occurs at an early stage of puberty, 2-4 years before LH reaches the same levels.

FSH is elevated in Klinefelter syndrome and in some subjects with precocious puberty. It is decreased with precocious puberty related to adrenal tumors or congenital adrenal hyperplasia. Normal FSH in an adult nonovulating female, represents dysfunction at the central nervous system hypothalamic/pituitary level, and a "normal" value should in such a setting be considered pseudonormal.

High LH:FSH ratio (over 1.5) is found in the polycystic ovary syndrome.4