Endocrinology in ART

Question 1

Does FSH have a long or short half life?

Answer 1

Long - 30 hours

Question 2

What are the clinical implications of the long half life of FSH?

Answer 2

• A plateau of FSH is reached after around 5 days.

- FSH accumulation is still observed for a few days following cessation of FSH administration

Question 3

On what cells does LH act during the follicular phase and what does it do?

Answer 3

Acts directly on theca cells where LH receptors are present and causes a tonic production of androgens.

Question 4

Does Lh have a long or short half life?

Answer 4

Short

Question 5

What drugs, used in IVF stop the premature LH surge?

Answer 5

GnRH agonists

Question 6

Describe steroid hormone receptors

Answer 6

• Intracellular (cytoplasm or nucleus)
• Nuclear receptor family include oestrogen and androgen receptors
• The steroid/receptor complex binds to DNA response elements and result in gene transcription

Question 7

What is the target cells of LH in the male and female?

Answer 7

Male: Leydig cells
Female: Theca cells

Question 8

Describe what LH actually does in its target cells?

Answer 8

Increases the expression of steriodogenic acute regulatory proteins (StAR) which promotes the transfer of cholesterol to the inner mitochondrial membrane.
At the inner mitochondrial membrane cholesterol is converted to pregnenolone by the action of p450scc.
Mutations in StAR will result in defective transport of cholesterol to the inner mitochondrial membrane and result in reduced or no steroid hormone production.

Question 9

Describe how testosterone is produced

Answer 9

1. LH initiates the production of pregenolone
2. Pregenenolone is then converted to DHEA in a two step process mediated by 17, 20 alpha hydroxylase.
3. DHEA is then rapidly converted to testosterone via the intermediates androstenediol and androstenedione..

Question 10

Describe how Dihydrotestosterone is produced

Answer 10

Testosterone is converted to dihydrotestosterone by the action of 5 alpha reductase in target tissues.

Question 11

Which is more potent; testosterone or dihydrotestosterone?

Answer 11

Dihydrotestosterone

Question 12

Describe the synthesis of oestrogens in the female?

Answer 12

1. Granulosa cells are stimulated by LH to produce pregnenolone.
2. Pregnenolone diffuses out of these cells and into theca cells.
3. Theca cells express 17, 20 lyase and 3 beta HSD which mediates the conversion of pregnenolone to androstenedione via DHEA.
4. Most androstenedione returns to the granulosa cells and is converted to oestrone by aromatase.
5. Oestrone is then converted to oestradiol by 17beta HSD

Question 13

What does aromatase do?

Answer 13

Converts androstenedione to oestrone

Question 14

Whereabouts is androstenedione converted to oestrone?

Answer 14

Granulosa cells

Question 15

Describe the synthesis of progesterone

Answer 15

1. Progesterone is synthesised from pregnenolone by the action of 3 beta HSD in the corpus luteum, the placenta and the adrenals

Question 16

What is primary amennorhea?

Answer 16

Never had a period

Question 17

What is secondary amennorhea?

Answer 17

Had a period before but they have ceased.

Question 18

What hormone tests should be done on all patients presenting with oligo or amenorrhea?

Answer 18

LH
FSH
Oestradiol
Thyroid tests
Prolactin

Question 19

What defines female hypogonadism?

Answer 19

Low oestrogen levels

Question 20

What is primary hypogonadism?

Answer 20

Problems with the ovaries

Question 21

What is secondary hypogonadism?

Answer 21

Problem with the hypothalamus or pituitary gland

Question 22

What will FSH and LH levels be like in primary hypogonadism?

Answer 22

High

Question 23

What will FSH and LH levels be like in secondary hypogonadism?

Answer 23

Low

Question 24

What are the FSH readings required to make a diagnosis of premature ovarian failure?

Answer 24

Over 30 on 2 separate occasions at least one month apart.

Question 25

What age is classed as premature ovarian failure?

Answer 25

Below 40

Question 26

What are the LH levels like in PCOS?

Answer 26

LH hypersectretion (high)