Endocrine Mix

Question 1

function of PTH in bone?

Answer 1

binds to osteoblasts which activates osteoclasts triggering bone resorption and release of calcium

Question 2

function of PTH in kidneys?

Answer 2

increases reabsorption of calcium and magnesium in the distal convoluted tubule
decreases reabsorption of phosphate

Question 3

function of PTH in gut?

Answer 3

increases gut absorption of calcium by activating Vitamin D

Question 4

what cells secrete PTH?

Answer 4

chief cell in parathyroid glands

Question 5

what drives growth in each stage of growth?

Answer 5

infancy (birth - 2yrs) = nutrition and insulin
childhood (2-11) = GH and thyroxine
puberty (12-18) = sex hormones and GH

Question 6

features of primary hyperaldosteronism?

Answer 6

hypertension
muscle weakness (due to low potassium)
hypokalaemia
alkalosis

Question 7

how is primary hyperaldosteronism investigated?

Answer 7

aldosterone : renin ratio = first line
- will be high
CT scan and adrenal vein sampling

Question 8

how is primary hyperaldosteronism managed?

Answer 8

adrenal adenoma = adrenalectomy

bilateral adrenocortical hyperplasia = aldosterone antagonist (spironolactone)

Question 9

what is cholesterol converted to in the formation of steroid hormones?

Answer 9

pregnenalone

Question 10

what is waterhouse freidrichson syndrome?

Answer 10

adrenal gland failure due to a previous bleed in the adrenal gland as a result of a bacterial infection
most common cause = Neisseria meningitides

Question 11

how can increased exercise affect blood sugar in diabetes?

Answer 11

causes early and late decrease in blood sugar due to uptake of glucose in muscles

Question 12

what is congenital adrenal hyperplasia?

Answer 12

group of autosomal recessive disorders causing defects in enzymes involved in conversion of cholesterol to mineralocorticoids, glucocorticoids and sex steroids

Question 13

how does hyperplasia occur in CAH?

Answer 13

low cortisol > increased ACTH > stimulation of steroid producing cells > hyperplasia to try and accommodate for loss of function

Question 14

what is the most common cause of CAH and how does it present?

Answer 14

21 hydroxylase deficiency

• virilisation of female genitalia
• precocious puberty in males
• most have a salt losing crisis at 1-3 weeks old

Question 15

name 2 other causes of CAH and how do they differ from 21 hydroxylase deficiency?

Answer 15

11-beta hydroxylase deficiency
- same apart from also has hypertension and hyperkalaemia
17 hydroxylase deficiency
- non-virilising in females
- intersex in males
- causes hypertension

Question 16

what is Conn’s syndrome and what are the 2 main causes?

Answer 16

primary hyperaldosteronism

• adrenal adenoma
• diffuse/nodular hyperplasia of both adrenals

Question 17

triad of features in conns syndrome?

Answer 17

hypertension
alkalosis
hypokalaemia

Question 18

how can conns syndrome be distinguished from renal artery stenosis?

Answer 18

conns = low renin
RAS = high renin

Question 19

name 2 causes of acute adrenocortical hypofunction

Answer 19

rapid withdrawal of steroid medication

massive adrenal haemorrhage

Question 20

what can cause chronic adrenocortical hypofunction?

Answer 20

autoimmune adrenalitis
infection
metastatic malignancy
anti-phospholipid syndrome
rare - sarcoidosis, amyloidosis, haemochromatosis

Question 21

symptoms of addisons disease only occur after what percentage of adrenal function is lost?

Answer 21

90%

Question 22

what are the symptoms of addisons disease?

Answer 22

weakness and fatigue
vomiting
weight loss
diarrhoea
pigmentation of skin/mucosal membranes (esp in creases)
hypotension (due to lack of aldosterone)

Question 23

what biochemistry is found in addisons disease?

Answer 23

hyponatraemia
hyperkalaemia
low aldosterone
hypoglycaemia (due to reduced glucocorticoids - cortisol induced gluconeogenesis)

Question 24

what is addisonian crisis and how does it present?

Answer 24

medical emergency of severe adrenal insufficiency
hypovolaemic shock
fever
abdominal pain
vomiting
convulsions
shock death

Question 25

most common presentation of MEN1?

Answer 25

hypercalcaemia

Question 26

mutation in MEN1?

Answer 26

autosomal dominant mutation of MEN1 tumour suppressor gene | loss of function mutation - reduced protein production

Question 27

what is carney complex?

Answer 27

hereditary mutation of protein kinase A leading to uncontrolled cell proliferation and adrenal hyperplasia

Question 28

features of carney complex?

Answer 28

spotty skin pigmentation myxomas benign or cancerous tumours can lead to development of cushings (adrenocortical hyperplasia leads to excess cortisol production)

Question 29

what is primary pigmented nodular adrenocortical hyperplasia associated with?

Answer 29

carney complex (causing cushings)

Question 30

6 features of mccune Albright syndrome?

Answer 30

``` café au lait polyostotic fibrous dysplasia (bones) precocious puberty in females thyroid nodules GH excess cushings syndrome ```

Question 31

what is a neuroblastoma?

Answer 31

tumour of primitive looking cells in the adrenal medulla which indicate differentiation towards ganglion cells

Question 32

neuroblastoma is usually discovered by what age?

Answer 32

18 months

Question 33

what cells is a phaeochromocytoma derived from and what do they do?

Answer 33

chromaffin cells of adrenal medulla | - chromaffin cells secrete catecholamines

Question 34

features of phaeochromocytoma?

Answer 34

``` hypertension (catecholamines activate sympathetic nervous system) cardiovascular complications - heart failure - infarction - arrhythmias - stroke ```

Question 35

how is phaeochromocytoma diagnosed?

Answer 35

presence of catecholamines and metabolites in the urine | CT

Question 36

how is phaeochromocytoma managed?

Answer 36

full alpha then beta blockade | laparoscopic adrenalectomy

Question 37

tumour cells in phaeochromocytoma create small nests known as what?

Answer 37

zellballen

Question 38

which tumour is known as the 10% tumour and why?

Answer 38

phaeochomocytoma 10% are bilateral 10% are extra-adrenal 10% are familial (associated with MEN1 and MEN2)

Question 39

phaeochromocytoma is likely to metastasise where?

Answer 39

bone | also lymph nodes, lung and liver