Reproductive: Male hypogonadism Flashcards
Male hypogonadism
Clinical syndrome comprising of signs, symptoms and biochemical evidence of testosterone deficiency
Male: HPG axis (4)
Hypothalamus is stimulated by kisspeptin to release pulses of GnRH
Anterior pituitary is stimulated by GnRH to release LH and FSH
Gonad (testes) are stimulated by LH and FSH to produce testosterone
Testosterone provides negative feedback to hypothalamus and pituitary
Testosterone Production (3)
Produced by Lydia Cells under control of LH
Majority is bound by SHBG and albumin
Converted to dihydrotestosterone (highly active form) and oestradiol
primary male hypogonadism
Testes
Secondary male hypogonadism
Hypothalamus or anterior pituitary
Primary Hypogonadism Mechanism
Testes primarily affected
Decreased testosterone results in decreased negative feedback
Anterior pituitary secretes higher amounts of LH and FSH
Hypergonadotrophic hypogonadism
Spermatogenesis affected more than testosterone production
Primary Hypogonadism Aetiology
Congenital
- Klinefelter’s Syndrome
- Crytorchidism
- Y-chromosome micro deletions
Acquired
- testicular torsion/ trauma
- chemotherapy/ radiation
- Varicocele
- Orchitis (mumps infection)
- Infiltrative diseases
- Medications (glucocorticoids, ketoconazole)
Klinefelters Syndrome
Most common genetic cause of hypogonadism
Caused by nondisjunction (normally 47 XXY)
Presentation variable
Klinefelters diagnosis
Diagnosed by karyotyping
Klinefelters Clinical Features
Affected men are infertile (due to tubular damage)
Small, firm testes
Increased incidence of cryptorchidism, learning disability and psychosocial issues
increased risk of breast cancer and non-Hodgkins lymphoma
Secondary hypogonadism
Hypothalamus/ pituitary affected
Testes capable of normal function
LH/FSH low despite low testosterone
Hypogonadotrophic hypogonadism
Spermatogenesis and testosterone production equally affected
Secondary hypogonadism aetiology
Congenital
- Kallmanns Syndrome
- Prader-Willi syndrome
Acquired
- Pituitary damage (tumours, infiltrative disease, infection, apoplexy, trauma)
- Hyperprolactinaemia
- obesity, diabetes
- medications (steroids, opiates)
- acute systemic illness
- eating disorders, excessive exercise
Kallmann Syndrome
Genetic disorder characterised by isolated GnRH deficiency and hyposmia or anosmia
Kallmann Syndrome associated abnormalities
Unilateral renal agenesis
Red-green colour blindness
Cleft lip/palate
Bimanual sykinesis
Hypogonadism Features: Pre-pubertal onset
Small male sex organs Decreased body hair High pitched voice Low libido Gynaecomastia Decrease bone and muscle mass
