Diagnosis of adrenal disorders Flashcards Preview

Endocrine > Diagnosis of adrenal disorders > Flashcards

Flashcards in Diagnosis of adrenal disorders Deck (36)
Loading flashcards...
1

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

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

Medulla: catecholamine synthesis and function (adrenaline and noradrenaline)

 

2

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

Cortex: Cushing's and Addison's

Medulla: Pheochromocytomas

3

Describe the structure of the adrenal cortex?

What is secreted form each layer?

Zona glomerulosa: mineralocorticoids (aldosterone)

Zona fasiculata: glucocorticoids (cortisol)

Zona reticularis: sex steroid, androgens 

4

Describe the difference between cortisol, hyrdrocortisone and cortisone?

Cortisol = hydrocortisone

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

5

What are steroid hormones synthesised from?

Cholesterol

6

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

Mineralocorticoid pathway (aldosterone)

Glucocorticoid pathway (cortisol)

Sex hormone pathway (oestrogen and testosterone)

7

Describe the actions of glucocorticoids?

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)

 

8

Describe the effects of excess cortisol?

Weight gain

Wasting of muscle, skin and bone

Hyperglycaemia

Hypertension

Inhibiiton of linear growth

9

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

Hyperglycaemia: muscle amino acid > glucose

Hypertension: salt retention 

10

Describe the two types of hypercortisolism and their causes?

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 

11

Describe the features of Cushing's disease?

Hypertension 

Apparent obesity

Muscle wasting, thin skin

Metabolic derangements (diabetes)

12

Describe the rationale behind the dexamethasone suppression test?

What is it used to test for?

Used to test for suspected Cushing's 

Dexamethasone feeds back to piuitary and switches off cortisol production 

13

Describe how suspected Cushing's disease can be investigated?

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 

14

Describe the effects of cortisol deficiency?

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

Hypotension

Darkening of skin

Muscle weakness

Increased susceptibility to infection

Death

 

15

Why does darkening of the skin occur with cortisol deficiency?

ACTH stimulated > MSH stimulated > melanocytes produce melanin

16

Describe the causes of adrenocortical insufficiency?

Enzyme defect in cortisol biosynthesis

Metabolic defect

Autoimmune adrenal destruction (most common)

Infectious disease > adrenal destruction

17

What is the most common cause of adrenocortical insufficiency?

Autoimmune destruction : Addison's disease

18

What is Addison's disease?

Adrenal insufficiency due to destruction of adrenals, usually autoimmune destruction 

19

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

Salt-wasting state > low Na, high K

20

Describe the treatment for Addison's disease?

Cortisol and fludrocortisone (aldosterone analogue)

21

Describe the common sites of Addisonian pigmentation?

Knuckles

Knees

Gums and oral mucosa

22

Describe the effects of excess androgens?

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

Describe the cause of congenital adrenal hyperplasia?

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

 

 

24

Describe the presentation of congenital adrenal hyperplasia?

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

Describe the treatment for congenital adrenal hyperplasia?

Replace cortisol and aldosterone as early as possible 

26

Describe the clinical uses of glucocorticoids?

Replacement therapy if inadequately produced 

Anti-inflammatory and immunosuppressive effects

27

What regulates mineralocorticoid (aldosterone) secretion?

Increased K in ECF

Ang II

(salt and water deficit)

28

Describe the actions of mineralocorticoids?

Increased resorption of Na

Increased resorption of water

Increased excretion of K from kidney DT

29

Describe the effects of aldosterone excess and insufficiency?

Excess: hypertension, weakness

 

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

30

Why does weakness occur in aldosterone excess?

Hypokalaemia