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Kidneys and Hormones > Clinical aspects of adrenal function > Flashcards

Clinical aspects of adrenal function Flashcards

1
Q

What types of hormones are secreted by the adrenal cortex?

A

Steroid hormones

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2
Q

What are steroid hormones derived from?

A

Cholesterol

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3
Q

What are the hormones released by the adrenal cortex?

A

Glucocorticoids
Mineralocorticoids
Androgens

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4
Q

What can happen when glucocorticoids are found in excess?

A

Can mineralocorticoid properties

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5
Q

How do steroids affect target cells?

A

Enter the nucleus and affect gene transcription

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6
Q

What is the function of mineralocorticoids?

A

Salt and water retention

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7
Q

What effects do mineralocorticoids have when found in excess?

A

Glucocorticoid effects

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8
Q

What controls androgen release from the adrenal cortex?

A

Puberty and pituitary gland

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9
Q

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

A

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

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10
Q

What types of hormones does the adrenal medulla release?

A

Catecholamines - amines

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11
Q

What receptors to catecholamines bind to on target cells?

A

G-protein coupled receptors

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12
Q

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

A

They are predominantly synthesized by the sympathetic nerve endings

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13
Q

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

A

Zona fasciculata

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14
Q

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

A

Cortisol

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15
Q

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

A

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
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16
Q

How do you diagnose Cushing’s syndrome?

A
  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
Q

Treatment of Cushing’s syndrome

A

Surgery

Drugs

18
Q

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

A

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
Q

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

A

Zona fasciculate and glomerulosa

20
Q

What is characterised in Addison’s disease?

A

Inadequate secretion of hormones from the adrenal cortex

21
Q

What are the causes of Addison’s disease

A
  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
Q

What diagnostic test can be performed to diagnose Addison’s

A

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

23
Q

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

A

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
Q

What are the symptoms of Addison’s?

A

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

25
Q

What is congential adrenal hyperplasia?

A

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
Q

What is characterised in congenital adrenal hyperplasia?

A

Increase in the production of sex hormones

Low level of glucocorticoids and mineralocorticoids in the blood

27
Q

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

A

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

Sex hormones and glucocorticoids/mineralocorticoids share the same precursors

28
Q

What factors determine the symptomology of the patients?

A

Age and the level of blockage of metabolic pathways

29
Q

What are the symptoms of congenital adrenal hyperplasia?

A

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
Q

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

A

In the US - babies screened for 17 hydroxyprogesterone intermediate

Elevated in congenital adrenal hyperplasia patients

31
Q

What is Pheochromocytoma?

A

Benign neuroendocrine tumours in the adrenal medulla

32
Q

What does Pheochromocytoma cause?

A

Excess secretion of catecholamines from the adrenal medulla

33
Q

How do you diagnose Pheochromocytoma?

A
  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
Q

What symptoms does Pheochromocytoma cause?

A

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
Q

How can you treat Pheochromocytoma?

A

Surgery

Drugs - alpha blockers to counteract hypertension problems

36
Q

What causes infertility?

A

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
Q

What does Aromatase do?

A

P450 enzyme

In the ovary, converts androgens -> oestrogen

Kidneys and Hormones (39 decks)

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