Urea and Electrolytes Flashcards
(37 cards)
when is urea raised
dehydration, gi bleed, increased protein breakdown (surgery, trauma infection, malignancy), high protein intake, drugs
when is urea decreased
in malnutrtion, liver disease and pregnancy
acute kidney injury diagnosis definition
a rise in serum creatinine >50% from baseline or urine output <0.5ml/kg/h for 6 hrs (oliguria)
what is creatinine blood conc specific for
determining kidney injury
pre renal causes of AKI
causes of reduced renal perfusion –> hypovolaemia, haemorrhage, sepsis, renovascular disease
intrinsic causes of AKI
acute tubular necrosis (ATN)(ischaemic or nephrotoxic), acute interstitial nephritis, acute glomerulonephritis
post renal causes of AKI
urinary tract obstruction (stones, stricture, prostate, tumour, blood clot)
how to investigate pre renal causes of AKI
fluid volume assessment
renal artery doppler (if suspected renovascular disease)
how to investigate intrinsic renal failure
urine dipstick –> will show haematuria and proteinuria in glomerulonephritis
in acute tubular necrosis –> urine is usually bland/
urine protein-creatinine ratio to quantify and monitor proteinuria
when is a renal biopsy done
if unexplained AKI, glomerulonephritis is suspected, positive nephritis screen, persistent ATN
how to investigate post renal failure
renal tract ultrasound –> will show dilated renal calcyces
chronic kidney disease definition
presence of marker of kidney damage (proteinuria) or GFR less than 60ml/min for >3 months
most common causes of CKD
diabetes (secondary to glomerular disease),
chronic hypertension,
chronic glomerulonephritis diseases (vasculitides)
others - drugs, PKD
when to dialyse (AEIOU)
Acidosis Electrolyte abnormalities - hyper- kalaemia, atraemia and calcaemia Intoxicants (methanol, lithium) Overload - acute pulm oedema Uraemia
when is regular dialysis required in chronic renal failure
when GFR is <15ml/min
causes of hypovolaemic hyponatremia (sodium lost so water follows)
if urinary Na+ >30 –> sodium is lost from kidneys = diuretics, addisons disease, kidney injury or osmotic diuresis
if urinary Na+ is <30 –> sodium lost elsewhere = diarrhoea/vomitting, fistula, burns
causes of euvolaemic hyponatremia (water is gained so it dilutes blood)
if urinary Na+ >30 AND urinary osm >100 –> from kidneys = SIADH, hypothyroidism, glucocorticoid insufficiency
if urinary Na+<30 or urinary osm<100 –> from elsewhere = drank too much water
causes of oedematous hyponatraemia
low Na+ is caused by excess ADH release secondary to intravascular fluid depletion (due to extravasation). = congestive heart failure, hypoalbuminaemia (nephrotic syn or cirrhosis)
causes of normovolaemic hypernatraemia
iatrogenic - excess IV crystalloids, sodium containing drugs
causes of hypovolaemic hypernatraemia
producing small vols of conc urine –> fluid loss (diarrhoea/vom, burns)
not producing small vols of conc urine (abnormal response) –> diabetes insipidus or osmotic diuresis (DKA)
causes of hypokalaemia (3 mechanisms)
increased renal excretion, increased cellular intake, other K+ loss (diarrhoea/vom)
why would the kidneys excrete more K+
diuretics, endocrine (steroids, Cushings disease, Conns syndrome), renal tubular acidosis, hypomagnesaemia
why would there be increased K+ cellular intake
salbutamol, insulin, alkalosis
causes of hyperkalaemia (3 mechanisms)
reduced renal excretion, excess K+ load or increased cellular release
