Biochemistry transition

Question 1

normal potassium range

Answer 1

3.5-5.3mmol/l

Question 2

2 most important factors determining potassium excretion

Answer 2

GFR and plasma potassium concentration

Question 3

severe hyperkalaemia

Answer 3

> 7mmol/l

Question 4

ECG findings of hyperkalaemia

Answer 4

tall tented T waves

widening of QRS complex (reflects altered myocardial contractility)

Question 5

categorisation of hyperkalaemia

Answer 5

decreased excretion
redistribution out of cells
increased intake

Question 6

causes of decreased excretion hyperkalaemia

Answer 6

renal failure

hypoaldosteronism (often occurs with ACEi/ARBs)

Question 7

causes of redistribution hyperkalaemia

Answer 7

potassium release from damaged cells (rhabdomyolysis, trauma, tumour lysis)
metabolic acidosis
insulin deficiency 
pseudohyperkalaemia 
hyperkalaemic periodic paralysis

Question 8

causes of increased intake hyperkalaemia

Answer 8

oral drugs administered as potassium salts
IV potassium - should not be given faster than 20mmol/hr except in extreme cases
blood products

Question 9

treatment of hyperkalaemia

Answer 9

Calcium gluconate/calcium chloride
insulin and glucose
dialysis

Question 10

what is pseudohyperkalaemia

Answer 10

increase in concentration of potassium due to its movement out of cells during or after venesection

Question 11

most common causes of pseudohyperkalaemia

Answer 11

delay in centrifuging separating plasma/serum from the cells/clot
In-vitro haemolysis
Increase in platelet and/or white cell count

Question 12

where is most potassium in the body found

Answer 12

intracellularly

Question 13

most common cause of hyperkalaemia

Answer 13

renal impairment

Question 14

symptoms of hypercalcaemia

Answer 14

neuro and psych features - lethargy, confusion, irritability, depression
GI - anorexia, abdominal pain, nausea, vomiting, constipation
Renal - thirst, polyuria, renal calculi
cardiac arrhythmias

Question 15

most common causes of hypercalcaemia `

Answer 15

primary hyperparathyroidism

hypercalcaemia of malignancy

Question 16

rarer causes of hypercalcaemia

Answer 16

inappropriate dosage of Vit D or metabolites 
granulomatous disease 
thyrotoxicosis 
thiazides 
immobilisation
renal disease 
calcium therapy 
diuretic phase of acute renal failure 
milk alkali syndrome

Question 17

treatment of hypercalcaemia

Answer 17

urgent if calcium >3.5mmol/l
IV saline
bisphosphonates (pamidronate - inhibits bone resorption)
surgical removal of parathyroid adenoma

Question 18

features of familial hypocalciuric hypercalcaemia

Answer 18

high calcium with detectable PTH

often misdiagnosed as primary hyperparathyroidism leading to unnecessary surgery

Question 19

what tests will give a correct assessment of hypercalcaemia severity

Answer 19

serum calcium
albumin concentration
these make up adjusted calcium

Question 20

clinical features of adrenal hypofunction

Answer 20

lethargy, anorexia, pigmentation of hands/mouth, abdo pain, weight loss, postural hypotension, vomiting, nausea, dehydration

Question 21

biochemical features of adrenal hypofunction

Answer 21

hyponatraemia, hyperkalaemia, elevated serum urea

Question 22

diagnostic test for adrenal hypofunction

Answer 22

short synacthen test

Question 23

causes of isolated aldosterone deficiency

Answer 23

adrenal lesion - 18hydroxylase defect

primary renin deficiency - anephric patients