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Endocrine > Diagnosis of adrenal disorders > Flashcards

Diagnosis of adrenal disorders Flashcards

1
Q

Describe the function of the adrenal cortex and the adrenal medulla?

A

Cortex: steroid hormone synthesis and function (glucocorticoids and mineralocorticoids)

Medulla: catecholamine synthesis and function (adrenaline and noradrenaline)

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2
Q

Describe the disease states associated with the adrenal cortex and the adrenal medulla?

A

Cortex: Cushing’s and Addison’s

Medulla: Pheochromocytomas

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3
Q

Describe the structure of the adrenal cortex?

What is secreted form each layer?

A

Zona glomerulosa: mineralocorticoids (aldosterone)

Zona fasiculata: glucocorticoids (cortisol)

Zona reticularis: sex steroid, androgens

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4
Q

Describe the difference between cortisol, hyrdrocortisone and cortisone?

A

Cortisol = hydrocortisone

Cortisone is an inactive metabolite of cortisol (can be metabolised back to cortisol in liver), very weak glucocorticoid

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5
Q

What are steroid hormones synthesised from?

A

Cholesterol

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6
Q

Describe the three basic pathways from cholesterol to steroid hormone synthesis?

A

Mineralocorticoid pathway (aldosterone)

Glucocorticoid pathway (cortisol)

Sex hormone pathway (oestrogen and testosterone)

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7
Q

Describe the actions of glucocorticoids?

A

Stimulation of gluconeogenesis in liver

Mobilisation of amino acids in muscle

Stimulation of lipolysis in adipose tissues

Immunosuppresion

(maintain homeostasis in face of physiological challenge)

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8
Q

Describe the effects of excess cortisol?

A

Weight gain

Wasting of muscle, skin and bone

Hyperglycaemia

Hypertension

Inhibiiton of linear growth

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9
Q

Describe why hyperglycaemia and hypertension occur in the presence of excess cortisol?

A

Hyperglycaemia: muscle amino acid > glucose

Hypertension: salt retention

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10
Q

Describe the two types of hypercortisolism and their causes?

A

ACTH-dependent: Cushing’s disease

Due to pituitary adenoma or ectopic ACTH syndrome

ACTH-indepedent: Cushing’s syndrome

Due to adrenal adenoma or carcinoma, ACTH-independent nodular hyperplasia or administration of glucocorticoids

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11
Q

Describe the features of Cushing’s disease?

A

Hypertension

Apparent obesity

Muscle wasting, thin skin

Metabolic derangements (diabetes)

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12
Q

Describe the rationale behind the dexamethasone suppression test?

What is it used to test for?

A

Used to test for suspected Cushing’s

Dexamethasone feeds back to piuitary and switches off cortisol production

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13
Q

Describe how suspected Cushing’s disease can be investigated?

A

24 hour urine free cortisol

Check diurnal variation: serum cortisol and plasma at 8am and midnight

Dexamethasone suppression test (check negative feedback is working)

Imaging as indicated

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14
Q

Describe the effects of cortisol deficiency?

A

GI symptoms: anorexia, nausea, vomiting, diarrheoa, weight loss

Hypotension

Darkening of skin

Muscle weakness

Increased susceptibility to infection

Death

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15
Q

Why does darkening of the skin occur with cortisol deficiency?

A

ACTH stimulated > MSH stimulated > melanocytes produce melanin

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16
Q

Describe the causes of adrenocortical insufficiency?

A

Enzyme defect in cortisol biosynthesis

Metabolic defect

Autoimmune adrenal destruction (most common)

Infectious disease > adrenal destruction

17
Q

What is the most common cause of adrenocortical insufficiency?

A

Autoimmune destruction : Addison’s disease

18
Q

What is Addison’s disease?

A

Adrenal insufficiency due to destruction of adrenals, usually autoimmune destruction

19
Q

Describe the electrolyte imbalance that occurs in Addison’s disease?

A

Salt-wasting state > low Na, high K

20
Q

Describe the treatment for Addison’s disease?

A

Cortisol and fludrocortisone (aldosterone analogue)

21
Q

Describe the common sites of Addisonian pigmentation?

A

Knuckles

Knees

Gums and oral mucosa

22
Q

Describe the effects of excess androgens?

A

Premature pubic hair

Hirutism

Acne

Enlargement of penis or clitoris

Behavioural changes

Linear growth spurt

Rapid epiphyseal fusion

Muscular body type

Deepening of voice

23
Q

Describe the cause of congenital adrenal hyperplasia?

A

21-hydroxylase deficiency in 90% > no cortisol secreted > increased ACTH >adrenal hyperplasia > increased sex hormone production

24
Q

Describe the presentation of congenital adrenal hyperplasia?

A

Females: infantile ambiguous genitalia, premature pubic hair and enlarged clitoris or adolescent hirsutism and acne

Males: adrenal crisis in newborn or premature sexual development at 2-3yo

25
Q

Describe the treatment for congenital adrenal hyperplasia?

A

Replace cortisol and aldosterone as early as possible

26
Q

Describe the clinical uses of glucocorticoids?

A

Replacement therapy if inadequately produced

Anti-inflammatory and immunosuppressive effects

27
Q

What regulates mineralocorticoid (aldosterone) secretion?

A

Increased K in ECF

Ang II

(salt and water deficit)

28
Q

Describe the actions of mineralocorticoids?

A

Increased resorption of Na

Increased resorption of water

Increased excretion of K from kidney DT

29
Q

Describe the effects of aldosterone excess and insufficiency?

A

Excess: hypertension, weakness

Deficiency: dehydration, salt depletion, postural hypotension, cardiac arrhythmias

30
Q

Why does weakness occur in aldosterone excess?

A

Hypokalaemia

31
Q

Why do cardiac arrhythmias occur in aldosterone deficiency?

A

Hyperkalaemia

32
Q

Why does death ensue within a few days of removal of the adrenal glands?

A

Aldosterone deficiency

33
Q

What is Conn’s syndrome?

A

Adrenocortical tumour secreting aldosterone

34
Q

Describe the presentation of Conn’s syndrome?

A

Hypertension

Weakness

High Na, low K, low renin

35
Q

Which disease state is asociated with the adrenal medulla and catecholamine production?

A

Pheochromocytoma

36
Q
A

Endocrine (17 decks)

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