Biochem Flashcards
What are potassium and sodium required for
membrane potential for muscle and nerve function
What is the normal range for potassium
3.5-5.5
What are the three types of causes for hyperkalaemia
- pseudohyperkalaemia
- renal causes
- transcellular potassium shift
What might cause transcellular potassium shift
- insulin deficiency
* acidosis/alkalosis
What is the main concern in hyperkalaemia?
myocardial hyperexcitability which can cause v-fib and cardiac arrest
What is the treatment for emergency hyperkalaemia
- calcium gluconate
* actrapid (insulin)
Why do you give calcium gluconate for hyperkalaemia
To protect the heart
Why do you give actrapid
insulin forces K+ intracellularly
What would cause you to give hyperkalaemia treatment?
- K+ >6.5
* ECG changes
metabolic (acidosis/alkalosis) may cause hyperkalaemia
metabolic acidosis may cause hyperkalaemia
which system regulates potassium levels
renin-angiotensin-aldosterone
What ECG changes might be seen in hyperkalaemia
- tall tented T waves
* short QT interval
When can you give potassium as a stat bolus
never
What are symptoms of hypokalaemia
- weakness and malaise
- muscle dysfunction
- paralysis
- arrhythmias
What treatment should be given for hypokalaemia
- oral K+ (sando-K)
* IV potassium infusion
What is the max speed of IV potassium
15-20mmol/h
What are the three classifications of hyponatraemia
- hypovolaemic
- normonvolaemic
- hypervolaemic
What is hypovolaemic hyponatraemia
large Na+ losses and slightly less water losses
usually diarrhoea or burns etc
What is normovolaemic hyponatraemia
increased water loss with normal sodium
What are causes of normovolaemic hyponatraemia
- adrenal insufficiency
- polydipsia/potomania
- SIADH
- hypothyroidism
What will urine be like in SIADH?
concentrated
What are is hypervolaemia hyponatraemia
increased fluid retention with small increase in sodium retention
oedema causes circular volume loss which causes ADH release and aldosterone release which both cause water reabsorption (and some Na+ reabsorption)
What are causes of hypervolaemia hyponatraemia
- congestive heart failure
- cirrhosis
- nephrotic syndrome
What are symptoms of hyponatraemia
- nausea and vomiting
- muscle cramps
- cerebral oedema
What are some causes of hypocalcaemia?
- pseudohypocalcaemia (eg hypoalbuminaemia)
- hypoparathyroidism
- CKD
- rhabdomyolysis
what hormones regulate calcium
- PTH
- calcitriol
- calcitonin
what does elevated urea indicate
dehydration
what are symptoms of hypercalcaemia
stones, bones, groans and psychic moans
What ECG changes are seen in hypercalcaemia
shortened QT interval
What treatment should be given for hypercalcaemia
- correct dehydration
- bisphosphonates
- treat underlying cause
What are some causes of hypercalcaemia
- hyperparathyroidism
- malignancy
- disorders that cause increased bone turnover
hypercalcaemia and hypophosphataemia indicates what?
hyperparathyroidism
what are symptoms of hypocalcaemia
- cramps
- spasms
- seizures
- Trousseau’s sign
- paraesthesia
What is Trousseau’s sign
Applying a blood pressure cuff to the arm causes carpo-pedal spasm
What ECG changes are seen in hypocalcaemia
prolonged QT interval
What is treatment for hypocalcaemia
oral calcium (calcichew) or IV calcium gluconate
What are the most common causes of hypomagnaesemia
malnutrition/diarrhoea
