Male endocrinology Flashcards
What is the structure and function of Sertoli cells?
Lie of the basement membrane of the seminiferous tubules and form tight junctions around the developing sperm, forming the blood testis barrier.
What is the structure and function of Leydig cells?
Found between the seminiferous tubules and produce testosterone, which is passed to the developing spermatocytes and the bloodstream.
Summarise the process of spermatogenesis
This occurs from the basal to the luminal compartment of the seminiferous tubules
- Spermatocytes undergo meiosis I and II to form spermatids
- Spermatids lose their cytoplasm and gain a flagellum to become mature spermatazoa
Describe the hormonal regulation of spermatogenesis
- GnRH from the hypothalamus stimulates LH and FSH secretion by the AP
- LH stimulates the Legdig cells to produce testosterone
- Testosterone and FSH drives spermatogenesis
- LH is regulated by negative feedback of testosterone
- Inhibin from Sertoli cells halts FSH production
How would one differentiate between primary and secondary hypogonadism?
Primary (testicular cause) - High LH/FSH
Secondary (hypothalamus/pituitary cause) - Low LH/FSH
Describe the pathophysiology of Kallmans syndrome
Failure of the hypothalamus to release GnRH, causing hypogonadatrophic hypogonadism (low FSH, LH and testosterone)
What investigations would indicate a diagnosis of Kallmanns syndrome?
- Anosmia (lack of smell)
- Low LH, FSH and testosterone
- Normal pituitary MRI/rest of function
What is the pathophysiology of Klinefelters syndrome?
Most common genetic cause of male hypogonadism - karyotype 47XXY. Causes low testosterone and high FSH/LH due to lack of negative feedback.
What is the clinical manifestation of Klinefelters?
Delayed/incomplete puberty
- Small penis/testicles
- Gynocomastia
- Feminine physique
- Poor hair growth
What are the treatment options for hypogonadism?
- IM or topical androgen replacement therapy
- GnRH, LH and FSH fertility treatment
