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Excessive FSH and LH are found in hypogonadism, anorchia, gonadal failure,1 complete testicular feminization syndrome, menopause, Klinefelter syndrome, alcoholism, and 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.
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- to 30-minute intervals and equal volumes of serum be pooled to decrease the effect of pulsatile secretion.
As with all tests containing monoclonal mouse antibodies, erroneous findings may be obtained from samples taken from patients who have been treated with monoclonal mouse antibodies or who have received them for diagnostic purposes.2 In rare cases, interference due to extremely high titers of antibodies to streptavidin and ruthenium can occur.2 The test contains additives, which minimize these effects.
FSH is a glycoprotein consisting of two subunits (α- and β-chains). Its molecular weight is approximately 32,000 daltons. FSH together with LH (luteinizing hormone), belongs to the gonadotropin family. FSH and LH regulate and stimulate the growth and function of the gonads (ovaries and testes) synergistically.3
FSH and LH are released in pulses from the gonadotropic cells of the anterior pituitary. The levels of the circulating hormones are controlled by steroid hormones via negative feedback to the hypothalamus. In the ovaries, FSH, together with LH, stimulates the growth and maturation of the follicle and hence also the biosynthesis of estrogens in the follicles.
In women, the gonadotropins act within the hypothalamus-pituitary-ovary regulating circuit to control the menstrual cycle.1,4 The FSH level shows a peak at midcycle, although this is less marked than with LH. Due to changes in ovarian function and reduced estrogen secretion, high FSH concentrations occur during menopause.1 The determination of FSH in conjunction with LH is utilized for the following indications: congenital diseases with chromosome aberrations, polycystic ovaries (PCO), amenorrhea (causes), and menopausal syndrome.
In men, FSH serves to induce spermatogonium development. Determination of the FSH concentration is used in the elucidation of dysfunctions within the hypothalamus-pituitary-gonads system. Depressed gonadotropin levels in men occur in azoospermia.1,3,5,6
1. Runnebaum B, Rabe T. Gynäkologische Endokrinologie und Fortpflanzungsmedizin. Berlin, Germany: Springer Verlag;1994. Band 1:17, 253-255; Band 2: 152-154, 360, 348. ISBN 3-540-57345-3, ISBN 3-540-57347-X.
2. FSH on Elecsys 1010/2010 and Modular Analytics E170, package insert 2007-10, V 14, Indianapolis, Ind: Roche Diagnostics; 2007.
3. Johnson MR, Carter G, Grint C, Lightman SL. Relationship between ovarian steroids, gonadotropins and relaxin during the menstrual cycle. Acta Endocrinol (Copenh). 1993 Aug; 129(2):121-125. PubMed 8372595
4. Beastall GH, Ferguson KM, O'Reilly DS, Seth J, Sheridan B. Assays for follicle stimulating hormone and luteinizing hormone: Guidelines for the provision of a clinical biochemistry service. Ann Clin Biochem. 1987 May; 24(Pt 3):246-262. PubMed 3111341
5. Schmidt-Mathiesen H. Gynäkologie und Geburtshilfe. Schattauer Verlag; 1992.
6. Scott MG, Ladenson JH, Green ED, Gast MJ. Hormonal evaluation of female infertility and reproductive disorders. Clin Chem. 1989 Apr; 35(4):620-630. PubMed 2522836
Jaakkola T, Ding YQ, Kellokumpu-Lehtinen P, et al. The ratios of serum bioactive/immunoreactive luteinizing hormone and follicle-stimulating hormone in various clinical conditions with increased and decreased gonadotropin secretion: Re-evaluation by a highly sensitive immunometric assay. J Clin Endocrinol Metab. 1990 Jun; 70(6):1496-1505. PubMed 2140831
Layman LC, Wilson JT, Huey LO, Lanclos KD, Plouffe L Jr, McDonough PG. Gonadotropin-releasing hormone, follicle-stimulating hormone beta, luteinizing hormone beta gene structure in idiopathic hypogonadotropic hypogonadism. Fertil Steril. 1992 Jan; 57(1):42-49. PubMed 1730329
