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
What does normal AM testosterone show?
Hypogonadism is unlikely
What should be done if LH/FSH levels are elevated?
Suspect hypergonadotrophic hypogonadism (Primary) which requires karyotyping and iron studies to fully diagnose
What should be done if LH/FSH levels are low?
Suspect hypogonadotrophic hypogonadism (Secondary), which requires prolactin and hormone studies, MRI and iron studies
When should AM testosterone be measured?
Between 8am and 11am
What are some conditions that can decrease testosterone levels?
Obesity
Insulin reisstance
Hypothyroidism
What treatment is given in hypogonadism, if fertility is important?
GnRH or gonadotrophin therapy
Sperm retrieval is used to take soerm samples
What are the aims of treatment in hypogonadism, if fertility is not important?
- Establish secondary sexual characteristics
- Maintain sexual function
- Improve body composition
- Improve quality of life
What is the main management option in hypogonadism, if fertility is not important?
Testosterone replacement therapy under the guidance of endocrinology
What are some formulations of testosterone?
- Transdermal gel
- Oral capsules
- IM injection
What are some contraindications for testosterone therapy?
Hormone responsive cancer (E.g. prostate, breast)
Severe sleep apnoea
Heart failure
How often is monitoring performed in testosterone therapy?
3-6 monthly whilst starting treatment and annually thereafter, testing for DRE and PSA, haematrocit and symptoms of sleep apnoea
