Hyponatraemia

Question 1

what does hyponatraemia depend on when trying to find the cause

Answer 1

volume status- hypovolaemic, euvolaemic, and hypervolaemic

Question 2

what happens in hypovolaemia

Answer 2

sodium loss

Question 3

what are the causes of hypovolaemiac hyponatraemia

Answer 3

extra renal- GI, skin(burns), ileus; primary renal (AKI, post obstruction); secondary renal (diuretics, hypoaldosteronism); cerebral salt wasting

Question 4

what happens in euvolaemia

Answer 4

dilutional- water is retained which dilutes Na+ in the plasma

Question 5

what are the causes of euvolaemic hyponatraemia

Answer 5

acute- primary polydipsia, iatrogenic (IV fluids). chronic- SIADH, hypothyroidism, hyperglycaemia

Question 6

what are the causes of hypervolaemic hyponatraemia

Answer 6

oedematous states- CCF, liver failure, cirrhosis, nephrotic syndrome, renal failure

Question 7

further investigations for hyponatraemia

Answer 7

plasma and urine osmolality (do at the same time- paired samples); urine sodium (how much urine is being excreted); other osmotically active substances in the plasma- do glucose, urea, calculate osmolar gap