Endocrine Aspects of Male Hypogonadism

Question 1

Describe features of primary hypogonadism?

Answer 1

High LH/FSH and Low testosterone

Question 2

Describe features of secondary hypogonadism?

Answer 2

Low LH/FSH and testosterone

Question 3

What hormones are synthesized in the Seminiferous tubules?

Answer 3

inhibin B and anti-Müllerian hormone

Question 4

What cells produce androgens?

Answer 4

Leydig cells

Question 5

What does LH contribute to the release of?

Answer 5

Testosterone

Question 6

What is FSH involved in?

Answer 6

spermatogenesis and Inhibin B secretion

Question 7

Describe the Mechanism of action of testosterone

Answer 7

T penetrates the cell
converted to 5a reductase
converted to DHT
binds androgen receptor

Question 8

Screening for hypogonadism

Answer 8

Initial screen = morning total testosterone
highest in the morning
Confirmation = repeat morning total testosterone

Question 9

What happens to SHBG in hypothyroidism?

Answer 9

decreases

Question 10

What happens to SHBG in hyperthyroidism?

Answer 10

increases

Question 11

Describe the synthesis of testosterone

Answer 11

Derived from cholesterol
-LH required to convert into pregnenolone

Pregnenolone into

• Progesterone
• DHEA

Both progesterone and DHEA can be converted to testosterone

Testosterone- converted into DHT and Estradiol (requires LH)

Question 12

Normal testosterone in a male

Answer 12

Produce about 7mg/day

-5% from adrenals

Question 13

How is testosterone transported around the body?

Answer 13

50% bound to albumin

44% bound to SHBG

2% free