Endocrine evaluation includes measurement of serum Testosterone(T), follicle-stimulating hormone (FSH), luteinizing hormone (LH) and prolactin.(P)
Testosterone is good measure of Leydig cells function. In normal males 2% of testosterone is unbound to protein (free), 54% is bound to albumin and other proteins, and 44% is bound to sex hormone-binding globulin. Serum testosterone is a good indicator of overall androgen production. If serum testosterone does not correlate with clinical history and physical examination, free testosterone should be measured together with sex hormone binding globulin, which may affect free testosterone level
LH and FSH are glycoprotein gonadotropic hormones secreted by pituitary gland. LH stimulates the Leydig cells to produce testosterone. LH is also important for the initiation and maintenance of spermatogenesis. FSH acts on the Sertoli cells and is important for the initiation of the spermatogenesis although this hypothesis now is being questioned. Rich line of studies demonstrated a considerable association between the destruction of germinal epithelium and elevated concentration of FSH. Among men presenting with azoospermia, serum FSH level that is greater than twice the upper limit of normal is suggestive of intrinsic testicular failure. However, normal FSH value does not exclude severe derangement of spermatogenesis and elevated FSH concentration is insufficient to indicate a damaged germinal epithelium. These data are especially important in azoospermic patient when sperm retrieval is planned. Patients with 2-3 times elevated FSH were found to have testicular sperm (areas of local spermatogenesis).
Prolactin level should be obtained in patients with a history of galactorrhea, visual changes and /or low levels of testosterone, FSH, LH levels. Hyperprolactinemia is a rare cause of subfertility in otherwise healthy men. Elevated Prolactin level may be associated with pituitary micro-or macroadenoma, therefore MRI of the brain is indicated. Prolactin is produced by the cells of the anterior pituitary. Elevated serum prolactin represents a pathological state that may indicate a significant underlying pituitary abnormality contributing to male reproductive failure. The majority of men with elevated serum prolactin levels will also manifest decreased serum testosterone. Significant elevation of prolactin may result from prolactin secreting pituitary macroadenoma and which requires head CT or MRI for the diagnosis.
Estradiol (E2) directly interferes with Leydig cell and Sertoli cell function . Estradiol level should be obtained in patients with gynecomastia, feminization, or patient treating with antiestrogens since the ratio E2/T is important for dose titration. If Estradiol/Testosterone ratio significantly increases during hormonal treatment, aromatase inhibitor testolactone may be added to decrease conversion T-----E2 and, therefore, decreaseestradiol level.
Thyroid hormones (T3/T4) evaluation is rarely indicated. Thyroid diseases may occasionally result in infertility (0.5% of infertile men), but this is usually associated with uncontrolled hypo-or hyperthyroidism.
|Hormones||Adult Plasma Level|
Each laboratory performing hormonal tests should indicate the particular reference range for adult hormonal plasma level. .
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