Małe hypogonadism Flashcards
How is testosterone circulated?
98 - 99.5% is bound to sex-hormone binding globulin (SHBG) and albumin
0.5-2% is free
What hormones is testosterone converted into?
Dihydrotestosterone (Highly active form) and oestradiol
What is male hypogonadism?
A clinical syndrome comprising of signs, symptoms and biochemical evidence of testosterone deficiency
What is meant by primary hypogonadism?
Condition affecting the testes
What is meant by secondary hypogonadism?
Condition affecting the hypothalamus or anterior pituitary
What are some features of pre-pubertal onset hypogonadism?
- Small male sexual organs (Testes, penis, prostate)
- Decreased body hair
- High pitched voice
- Low libido
- Gynaecomastia
- Eunuchoidal habitus (Tall, Slim, Long arms and legs)
- Decreased bone and muscle mass
What are some post-pubertal symptoms of male hypogonadism?
- Normal skeletal proportions, penis size and voice
- Decrease libido
- Decreased spontaneous erections
- Decreased pubic/axillary hair
- Reduced shaving frequency
- Decreased testicular volume
- Gynaecomastia
- Decreased muscle and bone mass
- Decreased energy and motivation
Describe the pathophysiology of primary hypogonadism
- Decreased testosterone
- Decreased negative feedback
- Increased LH/FSH production
- Hypergonadotrophic hypogonadism
- Spermatogenesis decreased moreso than testosterone
What are some congenital causes of primary hypogonadism?
- Klinefelter’s syndrome
- Cryptorchidism
- Y-chromosome microdeletions
What are some acquired causes of primary hypogonadism?
- Testicular trauma/torsion
- Chemotherapy/radiation
- Varicocele
- Orchitis (mumps)
- Infiltrative diseases e.g. haemochromatosis
- Medications e.g. glucocorticoids, ketoconazole
Describe the pathophysiology of secondary hypogonadism?
- Decreased LH/FSH production
- Decreased testosterone
- Spermatogenesis and testosterone production equally affected
What are some congenital causes of secondary hypogonadism?
- Kallmann’s syndrome
- Prader-Willi syndromeW
What are some acquired causes of secondary hypogonadism?
- Pituitary damage
- Hyperprolactinaemia
- Obesity, diabetes
- Medications (steriod, opiods)
- Acute systemic illness
- Eating disorders, excessive exercise
What are some causes of pituitary damage leading to secondary hypogonadism?
- Tumours
- Infiltrative disease
- Infection (TB)
- Apoplexy
- Head trauma
What is Kallmann’s syndrome?
Genetic disorder that causes that causes hypogonadotropic hypogonadism and an impaired sense of smell
How does Kallmann’s syndrome present?
- Hypogonadism
- Hyposmia/anosmia
- Isolated GnRh deficiency also associated with other abnormalities:
- Unilateral renal agenesis
- Red-green colour blindness
- Cleft lip/palate
- Bimanual synkinesis
What are some investigations required in Kallmann’s syndrome?
- Hormone testing
- Olfactory function testing
- Genetic testing
How is Kallmann’s syndrome managed?
Hormone replacement therapy (HRT)
What is the most common genetic cause of hypogonadism?
Kleinfelter syndrome
Describe the genetics of Kleinfelter syndrome
Usually genotype 47 XXY, can have 46 XY/47 XXY mosaicism
How does Kleinfelter syndrome present?
- Presentation variable and therefore diagnosis can be missed or late
- Affected men are typically infertile (due to tubular damage) and have small, firm testes
How is Kleinfelter syndrome investigated?
Karyotyping
What are some possible complications of Kleinfelter syndrome?
- Increased incidence of cryptorchidism, learning disability and psychosocial issues
- Increased risk of breast cancer and non-Hodgkin lymphoma
How is male hypogonadism diagnosed?
- AM testosterone
- LH/FSH levels
