Male infertility – Wikipedia, the free encyclopedia

Posted: May 4, 2015 at 12:12 pm

Male infertility refers to a male's inability to cause pregnancy in a fertile female. In humans it accounts for 40-50% of infertility.[1][2][3] It affects approximately 7% of all men.[4] Male infertility is commonly due to deficiencies in the semen, and semen quality is used as a surrogate measure of male fecundity.[5]

Factors relating to male infertility include:[6]

Pre-testicular factors refer to conditions that impede adequate support of the testes and include situations of poor hormonal support and poor general health including:

Male smokers also have approximately 30% higher odds of infertility.[9][not in citation given] There is increasing evidence that the harmful products of tobacco smoking kill sperm cells.[10][11] Therefore, some governments require manufacturers to put warnings on packets. Smoking tobacco increases intake of cadmium, because the tobacco plant absorbs the metal. Cadmium, being chemically similar to zinc, may replace zinc in the DNA polymerase, which plays a critical role in sperm production. Zinc replaced by cadmium in DNA polymerase can be particularly damaging to the testes.[12]

Common inherited variants in genes that encode enzymes employed in DNA mismatch repair are associated with increased risk of sperm DNA damage and male infertility.[13] As men age there is a consistent decline in semen quality, and this decline appears to be due to DNA damage.[14] (Silva et al., 2012). These findings suggest that DNA damage is an important factor in male infertility.

Testicular factors refer to conditions where the testes produce semen of low quantity and/or poor quality despite adequate hormonal support and include:

Radiation therapy to a testis decreases its function, but infertility can efficiently be avoided by avoiding radiation to both testes.[20]

Post-testicular factors decrease male fertility due to conditions that affect the male genital system after testicular sperm production and include defects of the genital tract as well as problems in ejaculation:

The diagnosis of infertility begins with a medical history and physical exam by a physician or nurse practitioner. Typically two separate semen analyses will be required. The provider may order blood tests to look for hormone imbalances, medical conditions, or genetic issues.

The history should include prior testicular or penile insults (torsion, cryptorchidism, trauma), infections (mumps orchitis, epididymitis), environmental factors, excessive heat, radiation, medications, and drug use (anabolic steroids, alcohol, smoking).

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Male infertility - Wikipedia, the free encyclopedia

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