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Flashcards in Clinical aspects of adrenal function Deck (37)
1

What types of hormones are secreted by the adrenal cortex?

Steroid hormones

2

What are steroid hormones derived from?

Cholesterol

3

What are the hormones released by the adrenal cortex?

Glucocorticoids
Mineralocorticoids
Androgens

4

What can happen when glucocorticoids are found in excess?

Can mineralocorticoid properties

5

How do steroids affect target cells?

Enter the nucleus and affect gene transcription

6

What is the function of mineralocorticoids?

Salt and water retention

7

What effects do mineralocorticoids have when found in excess?

Glucocorticoid effects

8

What controls androgen release from the adrenal cortex?

Puberty and pituitary gland

9

Why do androgens released from the adrenal cortex have little effect?

The androgens have weak effects until they are metabolised peripherally into testosterone

10

What types of hormones does the adrenal medulla release?

Catecholamines - amines

11

What receptors to catecholamines bind to on target cells?

G-protein coupled receptors

12

Why does a dysfunction in the adrenal medulla no affect the release of catecholamines to a large extent?

They are predominantly synthesized by the sympathetic nerve endings

13

What area of the adrenal cortex is affected by Cushing's?

Zona fasciculata

14

What hormone is elevated in the blood in Cushing's syndrome?

Cortisol

15

What is the source of high cortisol in Cushing's syndrome?

Three main causes:

1. Increase in production of ACTH from the pituitary gland = this is called Cushing's disease and is caused by pituitary adenoma

2. Ectopic tissues producing ACTH - cancers (small cell lung cancer)

3. Steroid drugs for clinical use

16

How do you diagnose Cushing's syndrome?

1. Look for increased levels of glucocorticoids

2. Measure urinary metabolites of cortisol

3. Measure ACTH - distinguishes adrenal from pituitary source

4. Suppression test - Dexamethasone. Synthetic steroid with glucocorticoid excess - when injected in high quantities should suppress release of ACTH

5. Imaging - localise the source of ACTH via imaging or nuclear medicine scan -> label molecule that binds to ACTH receptor

17

Treatment of Cushing's syndrome

Surgery
Drugs

18

What are possible side effects from Cushing's disease treatment?

Removal of adrenal glands = Nelson's disease

Pituitary gland loses its negative feedback

Grows in size = blindness

Increased production of ACTH = pigmentation. MSH (melanocortin stimulating hormone) is a precursor for ACTH

19

What area of the adrenal medulla does Addison's disease affect?

Zona fasciculate and glomerulosa

20

What is characterised in Addison's disease?

Inadequate secretion of hormones from the adrenal cortex

21

What are the causes of Addison's disease

1. Autoantibodies that attack the adrenal gland

2. Bad infection - rapid adrenal failure

3. Steroid drugs - if suddenly stops using. Since they have caused atrophy of the adrenal glands

22

What diagnostic test can be performed to diagnose Addison's

Inject ACTH. If the adrenal glands fail to respond - intrinsic adrenal disease/ atrophy

23

Why does the use of steroid drugs cause the adrenal gland to atrophy?

Activates the negative feedback loop so there is a decrease in ACTH production

ACTH stimulates survival and growth of adrenal cortical cells

Suppression of ACTH therefore, leads to adrenal cortex atrophy

24

What are the symptoms of Addison's?

Salt and water wasting - low blood pressure
Low blood glucose
Fatigue
Weight loss

25

What is congential adrenal hyperplasia?

A rare group of autosomal recessive conditions characterized by the mutation in production of steroid hormones


The most common = mutation in 21 hydroxylase enzyme - turns precursors into mineralocorticoids and glucocorticoids

26

What is characterised in congenital adrenal hyperplasia?

Increase in the production of sex hormones

Low level of glucocorticoids and mineralocorticoids in the blood

27

Why is there elevated sex hormone levels in the blood of congenital adrenal hyperplasia patients?

All the precursors that should become glucocorticoids and mineralocorticoids become sex hormones instead

Sex hormones and glucocorticoids/mineralocorticoids share the same precursors

28

What factors determine the symptomology of the patients?

Age and the level of blockage of metabolic pathways

29

What are the symptoms of congenital adrenal hyperplasia?

In females

If severe - birth, ambiguous genetalia
If milder - childhood/ adolescence, accelerated growth and hair growth
If mild - adulthood, infertility or menstrual problems

In males

If severe - problems producing glucocorticoids = salt and water retention, accelerated puberty and exaggerated growth

30

What tests can be done to check if baby has congentil adrenal hyperplasia?

In the US - babies screened for 17 hydroxyprogesterone intermediate

Elevated in congenital adrenal hyperplasia patients

31

What is Pheochromocytoma?

Benign neuroendocrine tumours in the adrenal medulla

32

What does Pheochromocytoma cause?

Excess secretion of catecholamines from the adrenal medulla

33

How do you diagnose Pheochromocytoma?

1. Suspicious if patient does not respond to hypertensive drugs
2. Measure the metabolites of adrenaline in the urine
3. Nuclear medicine scans - look for areas secreting an excess of catecholamines

34

What symptoms does Pheochromocytoma cause?

There is excess sympathetic activation

This leads to excess noradrenaline and adrenaline metabolites in the urine

Palpilations, weight loss, abdonminal pain, hypertension and anxiety

35

How can you treat Pheochromocytoma?

Surgery
Drugs - alpha blockers to counteract hypertension problems

36

What causes infertility?

Many problems

1. Local - sperm generation, pathology of uterine tubules

2. Adrenal related - Cushings in females leads to excess androgens/ congenital adrenal hyperplasia -> ambiguous genitalia

3. Conditions of the ovary - polycystic ovarian syndrome

37

What does Aromatase do?

P450 enzyme

In the ovary, converts androgens -> oestrogen