Transtornos Hormonales En Infertilidad Masculina

TRANSTORNOS HORMONALES EN INFERTILIDAD MASCULINA

Med Clin N Am 88 (2004) 367–385
Male factor infertility
Evaluation and management
Victor M. Brugh, III, MDa, Larry I. Lipshultz, MD

Endocrine disorders have been identified in up to 20% of infertile men. Serum testosterone and follicle-stimulating hormone (FSH) identify 99% of all endocrine abnormalities in men with soft testes and lessthan 1 million sperm per milliliter. Other potentially useful hormone parameters include luteinizing hormone (LH), prolactin, and estradiol, which should be assayed contingent on findings during history, physical examination, and initial hormone evaluation.

Endocrinopathies
The hypothalamic–pituitary–gonadal (HPG) axis is a complex integrated system that is necessary for normal reproduction. Thehypothalamus is the center of the reproductive hormonal axis because it receives input from many regions within the brain and feedback in the form of steroid and protein hormones from both the gonads and adrenal glands. The hypothalamus releases gonadotropin-releasing hormone (Gn-RH) from the preoptic and arcuate nuclei as the end result of its integrative function. Gn-RH, in turn, is secreted ina pulsatile fashion into the portal hypophyseal venous, which feeds the anterior pituitary. Gn-RH stimulates the release of LH and FSH from the anterior pituitary gland. LH release is modulated by feedback of androgens at both the pituitary and hypothalamic levels. The release ofFSH seems to be regulated further by negative feedback of both inhibin and activin from Sertoli’s cells of the testis.In the testis, LH stimulates testosterone production by Leydig’s cells, whereas FSH is crucial to the initiation and maintenance of spermatogenesis. Both LH and FSH are necessary for quantitatively normal spermatogenesis. Feedback within this axis is essential for normal function and it occurs at multiple levels, allowing for precise regulation of hormonal activity. Abnormalities anywhere in theHPG axis have the potential for a negative impact on fertility in the male. In general, endocrine defects leading to male infertility can be evaluated initially by assaying testosterone, LH, FSH, prolactin, and estradiol.

Se dividen en 4:
1. hipogonadismo hipogonadotropico
Hipogonadismo hipogonadotrópico: viene definido por una disminución de las cifras de FSH, LH y testosterona.

Origenhipotalamico,genético, Sd kallman, tumores o tx hipofisiarios, uso de esteroides anabólicos

Genetic endocrinopathies
Genetic abnormalities can cause hormone, growth factor, and receptor dysfunction affecting the HPG axis [8]. The following disorders are uncommon, but may severely impair male fertility. These disorders usually are caused by mutations, small deletions, or polymorphic expansionswithin specific genes involved in the endocrine or humoral regulation of sexual development and function

Disorders of production or secretion of gonadotropin-releasing hormone

Disorders resulting in abnormal synthesis and release of Gn-RH and subsequent low levels of FSH and LH without an anatomic cause are termed ‘‘idiopathic hypogonadotropic hypogonadism’’ [8]. Without adequate levels ofgonadotropins, androgen production and spermatogenesis fail.

Kallmann’s syndrome is the most common X-linked disorder in male infertility and occurs in approximately 1 in 10,000 to 1 in 60,000 live births [9]. A mutation in the Ka1 gene (Xp22.3) results in a deficiency in Gn-RH secretion from the hypothalamus [10]. Many patients with Kallmann’s syndrome are tall, anosmic, and present secondary tofailure of pubertal initiation. Because of the lack of FSH and LH stimulation of the testis, spermatogenesis is absent, as is testosterone production, and these men have firm prepubertal-sized testes and a small penis. Patients may also have congenital deafness, asymmetry of the cranium and face, cleft palate, cerebellar dysfunction, cryptorchidism, or renal abnormalities. Fertility can be...