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Disorders of male reproduction 

Disorders of male reproduction

Chapter:
Disorders of male reproduction
Author(s):

U. Srinivas-Shankar

and F.C.W. Wu

DOI:
10.1093/med/9780199204854.003.130802
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date: 30 March 2017

Luteinizing hormone (LH) stimulates biosynthesis of androgenic steroids by binding to specific surface membrane receptors on the Leydig cells in the testis. Testosterone is essential for male sexual differentiation, growth and function of the male genital tract, secondary sexual characteristics, sexual potency, and production of spermatozoa.

Hypogonadism

Clinical features—male hypogonadism describes the clinical complex associated with testosterone deficiency due to pathological conditions affecting the hypothalamic–pituitary–testicular axis. Symptoms and signs depend on the age of onset of androgen deficiency. Prepubertal presentation is with sexual infantilism, delayed puberty, and eunuchoidal body proportions. Postpubertal presentation is with diminished sex drive and erection, loss of ejaculation, muscle atrophy, poor stamina, decreased secondary sexual hair, decreased shaving frequency, and regression of spermatogenesis (reduced testicular volume).

Diagnosis—hypogonadism is confirmed by low serum testosterone measured between 08.00 and 10.00 h. Measurement of LH, follicle-stimulating hormone (FSH), and prolactin is required to differentiate between primary (high gonadotrophins) and secondary (low gonadotrophins) hypogonadism. Patients with hypogonadotrophic hypogonadism without the stigmata of Kallmann’s syndrome (anosmia, red–green colour blindness, synkinesis, nerve deafness, cleft lip or palate, and renal malformations) require full pituitary assessment to exclude an underlying pituitary tumour. Suspected Klinefelter’s syndrome should be confirmed by chromosome karyotyping. Ultrasonography and MRI scan are useful in locating ectopic or intra-abdominal testes. DNA analysis can help confirm the diagnosis of androgen resistance syndromes and some other rare causes of hypogonadism.

Cryptorchidism—the absence of one or both testes from the scrotum and the commonest birth defect of the male genitals. It results from the failure of the testis to descend during fetal development from an abdominal position into the scrotum and is associated with increased risk of testicular cancer.

Klinefelter’s syndrome (47,XXY)—the most common congenital cause of male hypogonadism and occurs due to the presence of an extra X chromosome derived from the meiotic nondisjunction of germ cells. Typically present with infertility in adulthood.

Management—the aims of treatment are to: (1) relieve the symptoms of androgen deficiency; (2) prevent the long-term consequences of androgen deficiency such as osteopenia; (3) reproduce physiological circulating and tissue levels of testosterone, dihydrotestoerone, and oestradiol; (4) induce fertility, if required, in hypogonadotrophic patients; (5) treat any specific underlying diseases. Before starting testosterone, patients over the age of 45 years should be checked for pre-existing occult prostatic cancer by digital rectal examination and measurement of prostate specific antigen. There are several testosterone formulations, each with specific advantages and disadvantages, with the choice depending on availability and the patient’s age and preference.

Infertility

Male infertility is caused by a heterogeneous group of disorders and accounts for over one-third of a couple’s infertility. The commonest cause is idiopathic azoo/oligozoospermia, which probably represents the end result of many conditions that disrupt normal seminiferous tubular functions, although discrete gene defects associated with impaired spermatogenesis are increasingly recognized, e.g. Klinefelter’s syndrome, Y chromosome microdeletions, mutations in the ligand binding or DNA binding domains of the androgen receptor. Other causes include (1) male accessory gland infections, usually due to chlamydia, gonococcus, Gram-negative enterococci, and tubercle bacilli—a major cause of curable male infertility; (2) testicular tumours—the most common malignancy in young adult men; (3) obstructive azoospermia—usually due to vasectomy or previous genitourinary infections; may be amenable to surgical correction; (4) sperm autoimmunity.

Laboratory investigation—conventional parameters of the semen analysis such as sperm density, percentage of motile sperm, quality of sperm movements, and sperm morphology provide a semiquantitative index of fertility potential. Testosterone and LH measurements are indicated only when there is clinical suspicion of androgen deficiency, Klinefelter’s syndrome, or sex steroid abuse. Chromosome karyotyping and Y chromosome screening should be performed in all patients with nonobstructive azoospermia or severe oligozoospermia.

Management—(1) Intrauterine insemination (IUI) is first-line therapy for infertility due to the male factor, factors ascribed to the uterine cervix, minimal to mild endometriosis—and unexplained infertility. (2) In vitro fertilization (IVF) involves gonadotrophin stimulation of the female, suppression of spontaneous ovulation, and collection of multiple oocytes by laparoscopy or by ovarian puncture guided by transvaginal ultrasonography, with fertilization of eggs achieved by coincubation with prepared spermatozoa. (3) Microinjection of a single live spermatozoon directly into harvested oocytes (ICSI) is the treatment of choice for severe oligozoospermia in those who have failed IUI and IVF, but there is an increase in de novo chromosomal abnormalities, major congenital malformations, and imprinting disorders in children born as a result of such techniques, hence genetic counselling should be offered to all couples considering these treatments. (4) Cryopreservation of semen should be offered to all men of reproductive age before anticancer chemotherapy, orchidectomy, or testicular irradiation.

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