U and Es Flashcards
what is diabetes insipidus
inability to produce or respond to ADH resulting in excessive urine production or thirst
what conditions may cause electrolyte disturbance
haemorrhage d and v intake pyrexia- increased loss diabetes mellitus or insipidus diuretic therapy endocrine disorder
what is the concentration of extracellular sodium
140 mmol/L
what is the extracellular K concentration
5 mmol/L
what physiological mechanisms compensate for electrolyte disturbance
thirst
ADH
renin
what part of the brain produces ADH
median eminence of posterior pituitary gland
in what conditions is urea raised
congestive heart failure
shock
MI
severe burns
what is creatinine
breakdown product of protein and muscle
higher in males usually
what electrolytes can be measured
sodium potassium chloride bicarb urea creatinine
why is electrolyte balance important
cellular homeostasis
cardiovascular
renal
electrophysiology
what is the intracellular sodium concentration
10 mmol/L
name some isotonic fluids in the body
blood, fistula fluid
how much hypotonic fluid loss would be insensible
3 L
how might hypotonic fluid loss occur
diarrhoea and vomiting
what can cause activation of the RAAS system
na depletion
haemorrhage
how do you determine ADH status
if urine is a lot more concentrated than plasma then ADH is activated
how do you determine RAAS status
measure plasma and urine sodium concentration
if urine sodium is less than 10 mmol/L then RAAS is active
why should fluid loss of 2L be replaced with isotonic fluid rather than hypotonic fluid
will not cause a fall in sodium and will not cause fluid redistribution
what tow substances are used as markers of renal function
urea and creatinine
what factors influence GFR
renal perfusion pressure
renal vascular resistance
glomerular damage
post glomerular resistance
what is normal GFR
90- 150 mL/min
bigger people have higher rate
older people have lower rate
what is nephrosis
aka nephrotic syndrome
oedema
protein loss
increased glomerular permeability
what can cause hyponatraemia
diuretics addison's Na losing nephritis nephrosis vomiting and diarrhoea burns oedema (increased fluid compartment) drugs hypothyroidism Kidney failure
what is SIADH
syndrome of inapropriate antidiuretic hormone
hormone is produced in the wrong place
what is osmotic diuresis
too much urine production caused by retention of a substance in the nephron e.g. glucose causing inability to reabsorb enough water
what is normal potassium range
3.6 - 5
disorders are often iatrogenic
what change in pH can cause hyperkalaemia
acidosis causing potassium to move out of cells
what change in pH can cause hypokalaemia
alkalosis which causes potassium to move inside the cells
what can cause hyperkalaemia
artifactual haemolysis drug therapy renal failure acidosis mineralcorticoid dysfunction cell death
how can hyperkalaemia be treated
correct acidosis
give glucose and insulin
ion exchange resins
dialysis
what can cause hypokalaemia
low intake increased urine loss tubular dysfunction vomiting and diarrhoea fistulae alkalosis insulin and glucose therapy
what are the symptoms of potassium depletion
lethargy muscle weakness arrhythmia polyuria alkalosis
how is potassium depletion treated
supplementation
oral/ iv
monitor
