LH Reagent- Jaj International

The gonadotrophins LH and FSH glycoproteins with a molecular weight of approx. 30,000 Dalton are secreted by the basophilic cells of the pituitary gland. Their pulsatile secretion is regulated by the hypothalamic gonadotrophin releasing hormone (GnRH, LHRH). In the female, the gonadotrophins stimulate the growth of ovarian follicles during the follicular phase. During the luteal phase, their secretion is inhibited by the influence of progesterone and estradiol. In menopausal women, there is a striking rise in FSH serum concentrations, while LH does not exceed the usual level of the mid-cycle peak. High postmenopausal LH and FSH levels are due to the absence of the progesterone/ estradiol response.

In the male, LH stimulates the testosterone production of the Leydig cells. In combination with FSH and testosterone, it also stimulates spermatogenesis. The secretion of LH is regulated by a negative feedback mechanism of testosterone; the regulation of FSH is subject to the influence of inhibin. During childhood, LH and FSH levels are normally too low to be detectable. With the beginning of puberty, FSH is the first gonadotrophin to reach detectable values.

The determination of LH and FSH plays an important role in the detection of dysfunctions of the pituitary-ovarian axis, clinically manifested by amenorrhea, oligomenorrhoea, anovulatory cycles and menorrhagia. For differential diagnosis between hypothalamic and pituitary disturbances, the GnRH and the clomiphene tests are widely used.

Determination of LH serum concentrations is also used as an indicator of ovulation in in-vitro fertilizations. In men, determination of gonadotrophins is mainly used for the differentiation between primary and secondary hypogonadism. In children and juveniles, LH and FSH determinations are indicated in case of either precocious or delayed puberty.

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