Explore 5-Minute Clinical Consult - view these FREE monographs:
-- The first section of this topic is shown below --
- FDA definition: Testosterone <300 ng/dL (in men)
- Testosterone is essential for normal sexual development and function.
- Testosterone levels may decline with aging and in certain disease states.
- Low androgen levels increase the risk of low-trauma fractures and are associated with a decline in sexual function, sense of well-being, muscle mass, and strength.
- System(s) affected: Body composition and strength; Bone; Cardiovascular; Reproductive; Mood; Central Nervous System; Hematologic
- Synonym(s): Hypogonadism; Hypoandrogenism; androgen deficiency in the aging male syndrome
- 12.3/1,000 person-years in the US
- Late-onset hypogonadism: 481,000 new cases in the US men 40–69 years old
- 2–4 million men in US; because of problems of definition, the prevalence in women is undetermined.
- 12% of men in their 50s; 28% between 70 and 79; 49% in men ≥80
- Obesity, type 2 diabetes, COPD
- Medications that affect testosterone production or metabolism
- Undescended testicles
- Trauma; infection; radiation or tumors of testis, pituitary, hypothalamus; chemotherapy
- Exposure to environmental endocrine modulators
- Chronic infections or inflammatory disease
Some chromosomal disorders are inherited:
- Klinefelter: XXY karyotype (small testis, eunuchoid body habitus, gynecomastia)
- Kallmann: Abnormal gonadotropin-releasing hormone (GnRH) secretion due to abnormal hypothalamus development (micropenis, anosmia)
General health maintenance, such as prevention and treatment of obesity
- Normal hypothalamic–pituitary–testis axis:
- Hypothalamus produces GnRH, which stimulates pituitary to produce follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
- LH stimulates the testis to produce testosterone.
- Testosterone inhibits production of LH through negative feedback.
- Primary testosterone deficiency: Testes produces insufficient amount of testosterone; FSH/LH levels are elevated.
- Secondary testosterone deficiency (also known as hypogonadotropic hypogonadism): Low testosterone from inadequate production of LH
- Congenital syndromes: Undescended testicles
- Orchiectomy; testicular trauma
- Infectious: Mumps orchitis, HIV/AIDS, tuberculosis
- Cushing syndrome
- Severe illness (e.g., renal disease, cirrhosis)
- Sickle-cell disease
- Obesity; obstructive sleep apnea
- Drugs that decrease production: Corticosteroids, ethanol, ketoconazole, spironolactone, marijuana, opioids, cimetidine
- Elevated prolactin:
- Dopamine antagonists block inhibitory dopamine effects on prolactin secretion: Neuroleptics, metoclopramide, etc.
- Idiopathic hypogonadotropic hypogonadism
- Radiation to the testis