Male hypogonadism Flashcards
Synthesis of testosterone
Derived from cholesterol
- LH required to convert into pregenolone
Pregnenolone into
- Progesterone
- DHEA
Both progesterone and DHEA can be converted to testosterone
TESTO—> DHT and estradiol (requires LH)
Testosterone is secreted from the…
Testes
Ovaries
Adrenal glands
Normal testosterone levels in men
7mg/ day
- 5 % from adrenal glands
Testosterone transport
Mainly albumin
- >50%
SHBG
- 44%
Around 2 % free
Testosterone secretion from testes
Secreted by Leydig cells, adjacent to semniferous tubules.
Inhibin B
- Function
- Secretion
Hormone secreted by sertoli cells in seminiferous tubules
Negatively inhibits FSH, LH secretion.
Anti-mullerian hormone
- Function
- Secretion
Inhibits development of female genital tract in male embryo.
Regulates sex hormone product
Secreted and synthesised by sertoli cells
Control of testosterone secretion
GnRH from hypothalamus secreted in a pulsatile fashion
- Stimulates LH and FSH secretion
LH stimulates testosterone secretion from Leydig cells.
FSH stimulates spermatogenesis and inhibin B secretion
Testosterone mechanism of action
Steroid hormone–> Passes through plasma membrane
- Enters into cell and is converted into dihydrotestosterone [DHT]
- 5-alpha reductase
- DHT binds to androgen receptor in nucleus
OR - Directly binds to nuclear androgen receptor
Testosterone effects
Spermatogenesis
Male phenotype in embryogenesis
Male pattern sexual maturation in puberty and adulthood.
Increases lean body mass, decreases fat mass.
Sexual behaviour
Linear bone growth, prostate and larynx development.
Causes of primary hypogonadism
Klinefelter syndrome
Cryptorchidism
Infection: mumps
Radiation
Trauma
Torsion
Idiopathic
Causes of secondary hypogonadism
Congenital deficiencies of GnRH
Hyperprolactinoma
Head trauma
Pituitary disorder
GnRH analog
Opioids
Illness
Anorexia
Clinical features of male hypogonadism
- First trimester
- Third trimester
- Prepubertal
First trimester
- Female/ ambiguous genitalia
- Partial virilization
Third trimester
- Micropenis
Prepubertal
- Does not undergo or complete puberty
Clinical features of male hypogonadism
Incomplete sexual development
- Eunuchodisim
Decreased sexual desire
Decreased spontaenous erections
Breast discomfort/ gynaecomastia
Decreased body hair
Infertility/ low sperm count
Short height
Low trauma fracture/ bone mineral density
Decreased muscle bulk/ strength
Hot flushes/ sweats
Less specific signs/ symptoms of hypogonadism
Decrease in:
Energy, motivation, aggressiveness
Depression, dysthymia
Poor concentration/ memory
Mild anaemia- normocytic
Increased body fat/ BMI
Decreased physical performance
Conditions with high prevalence of hypogonadism
HIV with weight loss
Sellar disease
Infertility
Osteoporosis
T2 DM
End stage Kidney disease
Meds that affect T cells
- Glucos
- Ketoconazole
- Opioids
COPD
Examination [6]
Body hair
Breast
Testicular and penis size
Muscle bulk and strenght
BMD
Arm spna
Investigations [9]
Serum testosterone
LH/ FSH
SHBG
Liver function tests
Semen
Karyotyping
Pituitary function
MRI
DEXA
Screening guideline
Initial
- Morning testo [highest]
Confirmatory
- Repeat morning total testo
DO NOT SCREEN WHEN
- Acute or subacute illness
If testo is low
- Exluded illness, drugs, nutritional deficiency
If SHBG suspected to be altered
- Free Testso
Factors that lower SHBG
Moderate obesity
Nephrotic syndrome
Hypothyroidism
Drugs
- Glucocorticoids
- Progestins
- Androgenic steroids
Factors that raises SHBG
Ageing
Hepatic cirrhosis
Hyperthyroidis
Anticonvulsants
Estrogens
HIV
Investigations if testo is low
- Normal/ Low LH, FSH
Suggestive of secondary hypogonadism
Check
- Prolactin
- Iron
- Pituitary hormones
- Possible pituitary MRi
Investigations for primary hypogonadism
Testosterone
- Low
LH and FSH high
Karyotype [Klinefelter]
Testicular examination
Treatment
Testosterone
- Gel
- Injection
- Buccal/ patch, pellet
Contraindications of testosterone
Breast/ prostate cancer
DRE showing lump/ hard prostate
PSA> 3ng/ml
Severe, untreated BPH
Erythrocytosis
Hyper-viscosity
Untreated OSA
Severe heart failure
Gynaecomastia
- Description
- Epidemiology
Benign proliferation of glandular male breast tissue
- Unilateral or bilateral
- at least 0.5cm in diameter
Common
- 60% of boys in puberty
- 30-70% men
Causes of gynaecomastia
Persistent pubertal gynaecomastia
Drugs
Idiopathtic
Cirrhosis
Malnutrition
Hypogonadism
Testicular tumour
Chronic renal insufficiency
Hyperthyroidism
Evaluation of male breaststissue
Onset of enlargement
Associated pain/ tenderness?
Is the increase in size glandular or adipose?
Breast cancer?
Testicular tumour?
Gynaecomastia investigations
Testo
LH/FSH
Prolactin
LFT< U+Es
B-hCG
Thyroid
Oestrogen
Mamogram
Gynaecomastia treatment
Reassurance
Treat cause
Tamoxifen [breast cancer]
Surgery
