T1 L19 Endocrine aspects of male hypogonadism

Question 1

What is testosterone?

Answer 1

Steroid hormone secreted by testes, ovaries and adrenals

Question 2

How much testosterone do young men produce per day?

Answer 2

7mg

<5% is from adrenal secretion

Question 3

Describe the distribution of testosterone in the blood

Answer 3

2% is present as free hormone
≥50% is bound to albumin
44% is bound to sex-hormone-binding globulin

Question 4

What are the 2 parts of the testes?

Answer 4

Seminiferous tubules

Interstitium

Question 5

Describe the seminiferous tubules in the testes?

Answer 5

Sertoli cells synthesis inhibin B and anti-mullerian hormones
Sperm are produced here

Question 6

Describe the interstitium of the testes

Answer 6

Contains Leydig cells which produce androgens

Contain peritubular myoid cells

Question 7

What is the role of LH in males?

Answer 7

Release of testosterone

Question 8

What is the role of FSH in males?

Answer 8

Involved in spermatogenesis and inhibin B secretion

Question 9

What is the mechanism of action of testosterone?

Answer 9

Penetrates target cells to stimulate growth and function of the cells
Androgen target cells convert testosterone to 5-a-dihydrotestosterone before it binds to androgen receptor
Testosterones can be aromatised to oestrogens

Question 10

What is the role of testosterone?

Answer 10

Regulation of gonadotrophin secretion by hypothalamic-pituitary system
Initiation & maintenance of spermatogenesis
Formation of male phenotype during embryogenesis

Question 11

What is male hypogonadism?

Answer 11

Decrease in one or both of the 2 main functions of the testes

• sperm production
• testosterone production

Question 12

Describe primary hypogonadism

Answer 12

Disease of the testes
Testosterone below normal
Serum LH and/or FSH above normal

Question 13

Describe secondary hypogonadism

Answer 13

Disease of hypothalamus or pituitary
Testosterone below normal
Serum LH and/or FSH normal or low

Question 14

What are the causes of primary hypogonadism?

Answer 14

Klinefelter syndrome
Cryptorchidism
Infection
Radiation
Trauma
Torsion
Idiopathic

Question 15

What are the causes of secondary hypogonadism?

Answer 15

Congenital GnRH deficiency
Hyperprolactinaemia
GnRH analogue
Androgen
Opioids
Illness
Anorexia nervosa
Pituitary disorder

Question 16

What are the symptoms and signs of male hypogonadism?

Answer 16

Incomplete sexual development
Decreased sexual desire, activity and spontaneous erections
Decreased body hair
Decreased muscle bulk and strength
Decreased mood, energy, motivation, aggression
Breast discomfort, gynaecomastia
Very small or shrinking testes
Low sperm counts
Hot flushes / sweats
Sleep disturbance
Mild anaemia

Question 17

What conditions have a high prevalence of hypogonadism?

Answer 17

Sellar mass, radiation to sella or other sellar diseases
Medications affecting testosterone production or metabolism e.g. glucocorticoids, ketoclonazole, opioids
HIV-associated weight loss
ESRD and maintenance haemodialysis
Moderate to severe COPD
Osteoporosis or low trauma frature
Type 2 diabetes mellitus
Infertility

Question 18

What medical history is relevant in hypogonadism?

Answer 18

Puberty and sexual development
Past / present major illness
Past / present nutritional deficiency
Drug history
Relationship problems
Sexual problems
Major life events
Related family history
Recent changes in body
Testicle problems

Question 19

What should be examined in male hypogonadism?

Answer 19

Amount of body hair
Breast exam for enlargement and tenderness
Size and consistency of testicles
Size of penis
Signs of severe and prolonged hypogonadism 
-loss of body hair
-reduced muscle bulk and strength
-osteoporosis
-smaller testicles
Arm span

Question 20

What investigations should be done in male hypogonadism?

Answer 20

Serum testosterone
LH / FSH
SHBG
LFT
Semen analysis
Karyotyping
Pituitary function testing
MRI
DEXA scan

Question 21

What can decrease SHBG?

Answer 21

Moderate obesity
Nephrotic syndrome
Hypothyroidism
Use of glucocorticoids, progestins and androgenic steroids

Question 22

What can increase SHBG?

Answer 22

Ageing
Hepatic cirrhosis
Hyperthyroidism
Anticonvulsants
Oestrogens
HIV infection

Question 23

What is the treatment for male hypogonadism?

Answer 23

Testosterone in form of gel, injection, buccal, patch or pellet

Question 24

What monitoring should be done during testosterone treatment for hypogonadism?

Answer 24

Testosterone
PSA
FBC
DRE
DEXA

Question 25

What contraindications are there to testosterone therapy?

Answer 25

Breast or prostate cancer
Lump / hardness on prostate exam by DRE
PSA >3ng/ml that hasn't been evaluated for prostate cancer
Severe untreated BPH
Erythrocytosis
Hyperviscosity
Untreated obstructed sleep apnoea
Severe heart failure (class III or IV)

Question 26

What is gynaecomastia?

Answer 26

Benign proliferation of glandular tissue of male breast

Diagnosed on exam as palpable mass of tissue above 5cm diameter

Question 27

What are the causes of gynaecomastia?

Answer 27

Persistent pubertal gynaecomastia
Drugs
Idiopathic
Cirrhosis or malnutrition
Hypogonadism
Testicular tumour
Hyperthyroidism
Chronic renal insufficiency

Question 28

What information is needed in a history for gynaecomastia?

Answer 28

Duration
Breast pain / tenderness
Systemic disease
Weight gain or loss
Use of medication / recreational drugs
Exposure to chemicals
Fertility
Sexual function
Family history

Question 29

What examination should be done for gynaecomastia?

Answer 29

Virilisation
Testicular size
Penis
Sign of CLD or CRF
Thyroid
Breast

Question 30

What investigations should be done for gynaecomastia?

Answer 30

Testosterone
LH / FSH
Prolactin
LFT / U&E
B-hCG
TFT
Oestrogen
U/S

Question 31

What is the treatment for gynaecomastia?

Answer 31

Conservative - reassurance
Treatment of cause
Tamoxifen
Surgery