Endocrine and Metabolic

Question 1

Addison’s disease and potassium

Answer 1

primary adrenal insufficiency- less aldosterone- HYPERkalemia (decreased K+ secretion)

Question 2

Conn’s syndrome and potassium

Answer 2

primary hyperaldosteronism- more aldosterone- increased K+ secretion- HYPOkalemia

Question 3

what is the most common cause of hypernatremia in the elderly?

Answer 3

dehydration- reduced intake and increased GI loss (diarrhoea, vomiting)

Question 4

how do you calculate anion gap

Answer 4

(Na+ + K+) - (Cl- + HCO-3)

Question 5

what is normal anion gap also known as?

Answer 5

hyperchloraemic metabolic acidosis
loss of bicarbonate (HCO₃⁻) is compensated by an equivalent increase in chloride (Cl⁻), maintaining a normal anion gap

Question 6

what are causes of normal anion gap metabolic acidosis

Answer 6

gastrointestinal - bicarbonate loss:
- prolonged diarrhoea (may also result in hypokalaemia)
-ureterosigmoidostomy
-fistula
renal tubular acidosis
drugs: e.g. acetazolamide
ammonium chloride injection
Addison’s disease

Question 7

in hyponatremia, how much should Na+ levels be raised when corrected?

Answer 7

4-6 mmol in 24 hours

Question 8

what is the investigation for phaeochromocytoma?

Answer 8

24h urinary metanephrines

Question 9

what conditions is pheochromocytoma ass with?

Answer 9

MEN type II, neurofibromatosis type 1, von Hippel-Lindau syndrome, 10% familial

Question 10

what is the management of pheochromocytoma?

Answer 10

surgery definitive, but pt must be first stabilised with medical: alpha blocker (phenoxybenzamine) before beta blocker (propranolol)

Question 11

what are the side effects of thyroxine therapy?

Answer 11

hyperthyroidism: due to over treatment
reduced bone mineral density (osteoporosis)
worsening of angina
atrial fibrillation

Question 12

what are the causes of raised prolactin (6 causes)

Answer 12

the p’s
pregnancy
prolactinoma
physiological
polycystic ovarian syndrome
primary hypothyroidism
phenothiazines, metoclopramide, domperidone

Question 13

what is the treatment for thyrotoxic storm?

Answer 13

beta blockers, propylthiouracil and hydrocortisone

Question 14

what is the definitive investigation for addison’s disease?

Answer 14

ACTH stimulation test (short synacthen test)- synthetic ACTH analogue stimulates cortisol secretion from adrenal glands. Plasma cortisol is measured before and 30 minutes after giving Synacthen 250ug IM. Adrenal autoantibodies such as anti-21-hydroxylase may also be demonstrated.

Question 15

what is an investigation that can be used for addison’s disease in primary care?

Answer 15

9 am serum cortisol can be useful:
> 500 nmol/l makes Addison’s very unlikely
< 100 nmol/l is definitely abnormal
100-500 nmol/l should prompt a ACTH stimulation test to be performed

Question 16

what type of metabolic disturbance is found in cushing syndrome?

Answer 16

hypokalemic metabolic alkalosis (increased cortisol activity - increased aldosterone)

excess cortisol activates mineralocorticoid receptors in kidneys

Question 17

what is the mechanism of action of empagliflozin?

Answer 17

SGLT2 inhibitor- reversibly inhibits sodium glucose transporter 2 in the renal PCT (reduce glucose absorption and increase urinary glucose excretion)

Question 18

what are the main side effects of SGLT2 inhibitors?

Answer 18

increased urine output, weight loss, urinary infections

Question 19

what are important adverse effects of SGLT2i?

Answer 19

Urinary and genital infection (secondary to glycosuria).
Normoglycaemic ketoacidosis
Increased risk of lower-limb amputation: feet should be closely monitored

Question 20

mechanism of action of gliclazide

Answer 20

Sulfonylureas- increase insulin release from beta-cells in the pancreas.

Question 21

exenatide MOA

Answer 21

GLP-1 mimetic- mimic incretin which is usually released in the gastrointestinal tract, and has the effect of increasing insulin production.

Question 22

sitagliptin MOA

Answer 22

DPP-4 inhibitors- block the action of DPP-4, an enzyme which breaks down incretin

Question 23

metformin MOA

Answer 23

Biguanides- act to decrease gluconeogenesis in the liver and increase insulin sensitivity.

Question 24

what are the TFTs in sick euthyroid syndrome?

Answer 24

low T3/T4 and normal TSH with acute illness

Question 25

what is sheehan’s syndrome

Answer 25

occurs when the anterior pituitary gland is damaged due to significant blood loss (PPH)

pituitary gland undergoes ischaemic necrosis which can manifest as hypopituitarism. The most common physical sign of Sheehan’s syndrome is a lack of postpartum milk production and amenorrhoea following delivery.

Question 26

what is the first-line diagnostic investigation of cushing’s syndrome?

Answer 26

low dose dex test- then high dose dex for localisation of excess cortisol

Question 27

what is the effect of PTH on calcium?

Answer 27

increases calcium levels

Question 28

what can PTH level be in primary hyperparathyroidism

Answer 28

normal or raised (if adenoma- can sustain normal or raised PTH, usually calcium should suppress it with -ve feedback)