Male endocrinology

Question 1

Explain the male HPA axis?

Answer 1

GnRH is released from the hypothalamus > LH & FSH release from the AP > act on the testes.

Question 2

What cell does LH act on?

Answer 2

Leydig cells > release of testosterone.

Question 3

What cell does FSH act on?

Answer 3

Sertoli cells > release of ABG & inhibin.

Question 4

What is the function of ABG?

Answer 4

Keeps testosterone in the seminiferous tubules.

Question 5

What is the function of inhibin?

Answer 5

Supports spermatogenesis & negative feedback.

Question 6

What is male hypogonadism?

Answer 6

Dysfunctioning gonads > low serum testosterone.

Question 7

What is primary hypogonadism?

Answer 7

Dysfunction within the gonads (i.e. failure of leydig cells).

Question 8

What would primary hypogonadism show on blood investigations?

Answer 8

Low testosterone.

Elevated FSH & LH.

Question 9

What causes primary hypogonadism?

Answer 9

Klinefelters syndrome.
Surgical castration.
Trauma.
Infections.
Chronic liver & kidney disease.
Drugs & alcohol.
Radiotherapy & chemotherapy.

Question 10

What is the treatment for primary hypogonadism?

Answer 10

Decanoate (synthetic testosterone).

PDE inhibitor - for erectile dysfunction.

Question 11

What is secondary hypogonadism?

Answer 11

Low testosterone due to failure to secrete or insufficient GnRH.

Question 12

What would secondary hypogonadism show on blood investigations?

Answer 12

Low testosterone.

Low FSH & LH.

Question 13

What are the causes of secondary hypogonadism?

Answer 13

Kallmanns syndrome.
Cushing syndrome.
Diabetes.
Hypopituitarism - low FSH & LH secretion.

Question 14

What is the treatment for secondary hypogonadism?

Answer 14

GnRH infusion.
HCG & FSH.
PDE inhibitor.

Question 15

What is Kallmanns syndrome?

Answer 15

Genetic disorder > failure of GnRH neurones to migrate to the hypothalamus > absent/low GnRH release.

Question 16

What is Klinefelters syndrome?

Answer 16

47 XXY.

Question 17

What are the symptoms of adult hypogonadism?

Answer 17

Small or absent testes.
Small prostate.
Gynaecomastia.
Infertility & sexual dysfunction.
Reduced hair growth.
Osteoporosis.

Question 18

What are the symptoms of pubertal hypogonadism?

Answer 18

Eunuchoid:
> lack secondary sexual characteristics.
> infantile genitalia.
>Gynaecomastia.
> infertility.

Question 19

What are the symptoms of foetal hypogonadism?

Answer 19

Development of a female.

Question 20

What is male infertility?

Answer 20

Inability to fertilise a fertile woman.

Question 21

What are the causes of male infertility?

Answer 21

Idiopathic.
Varicocele.
Mumps.
Hypogonadism.
Testicular cancer.
Drugs & alcohol.

Question 22

What are the signs of male infertility?

Answer 22

Oligospermia.
Azospermia.
Small testes.

Question 23

What is the treatment for male infertility?

Answer 23

Intracytoplasmic sperm injections.
Vasectomy reversal.
GnRH therapy - if infertility is due to secondary hypogonadism.

Question 24

What is androgen insensitivity syndrome?

Answer 24

X-linked autosomal recessive disorder.

Question 25

What are the main causes of AIS?

Answer 25

Mutations in the androgen receptor. | Mutations in the 5a reductase gene.

Question 26

What does 5a reductase do?

Answer 26

Converts testosterone in DHT which is required for masculinsation of the foetus.

Question 27

What are the signs of AIS?

Answer 27

``` Males born with ambigious genitalia: > blind ended vaginas. > small clitoris. > small testes present. > Bilateral inguinal hernias. ```

Question 28

What is the treatment for AIS?

Answer 28

Pre-pubertal orchidectomy. | Oestrogen replacement therapy.

Question 29

What is precocious puberty?

Answer 29

Puberty occurring at an unusually early age: > puberty before 7-8 years in females. > puberty before 9-10 years in males.

Question 30

What are the types of precocious puberty?

Answer 30

Central: > Gonadotropin dependant (i.e. increased release of gonadotropins from the HPG axis). Precocious pseudopuberty: > Gonadotropin independent (not due to increased release of gonadotropins from the HPG axis).

Question 31

What are the causes of central precocious puberty?

Answer 31

``` Idiopathic. Hypothalamic hamartoma - benign tumour that produces GnRH. Pineal gland tumour. Hypothyroidisim. CNS injury. ```

Question 32

What are the causes of precocious pseudopuberty?

Answer 32

Congenital adrenal hyperplasia. Adrenal or gonadal tumours. HCG secreting tumours - HCG is a analog of LH.

Question 33

What are the signs of precocious puberty?

Answer 33

Short stature. | Sexual precocity.

Question 34

What is the treatment for central precocious puberty?

Answer 34

GnRH agonist.

Question 35

What is the treatment for precocious pseudopuberty?

Answer 35

17a hydroxylase inhibitor (i.e. steroid synthesis inhibitor).