Flashcards in electrolyte disorders Deck (100)
what is U&Es?
urea and electrolytes
how do you measure U&Es?
through ions and biproducts in the blood which is direct - look at sodium, potassium, chloride, bicarbonate, urea and creatinine
how do you estimate U&Es?
through deduction - rather than direct - not possible in practice - look at water
what are electrolyte disorders?
they are abnormal electrolytes
how can electrolyte disorders result?
primary disease state, secondary consequence of a multitude of disease or iatrogenic
why is electrolyte maintenance important?
maintenance of cellular homeostasis, cardiovascular physiology such as sodium for BP, renal physiology such as sodium for GFR, electrophysiology - arrhythmias
what is the epidemiology of electrolyte disorders?
commonest chemical pathology test with 100000 cases per year
when are electrolytes measured?
haemorrhage, poor intake, increased loss, D&V, diabetes insipidus and mellitus, diuretic therapy and in endocrine disorders to increase the patient outcome
what concepts are important in electrolyte disorders?
volume - need to be able to deduce
contents - cannot use to determine treatment unless have concentrations and volumes
compartments - which one is it in - intra and extracellular
concentration - does not necessarily tell us if overloaded or depleted
rates of gain and loss - dynamic therefore can retain and get overloaded
what is the concentration of Na?
inside the cell it is low and distributes at roughly 100 - potassium is higher in the cell
what is sodium outside the cell?
higher - around 140mmol/L
what happens to the concentration in plasma as exercise with no hydration?
concentration increases as volume is depleted
normally the system is in equilibrium, what does changing any factor do?
causes the new steady state to be reached
what is the ECF distribution of water, sodium and potassium?
vascular - water will be 3L, sodium 140mmol/L and K 5mmol/L
interstitial - water 16L, Na 140mmol/L and K 5mmol/L
what is the ICF distribution of Na, K and H2O?
intracellularly there will be 23L of water, 10mmol/L of Na, and 150mmol/L of K
what is the total volume of water in the ECF and ICF?
what does loss of isotonic (similar to blood) fluid result from ?
can result from loss of blood or fistula fluid or haemorrhage
what are the characteristics of isotonic fluid loss?
no change in concentration of sodium, loss is from ECF, no fluid redistribution
what is loss of hypotonic solutions?
it is insensible loss such as vomiting and results in dehydration
where is the greatest loss in loss of hypotonic solution?
in the ICF - fluid is lost from the space and therefore there is a reduction in volume so increase in concentration meaning that water moves out of cells due to osmosis - cells shrink
what are the characteristics of insensible loss?
small increase in ICF sodium and fluid redistribution between the ECF and ICF
what are the characteristics of gain of isotonic solution?
this could be gain of saline drip - gain is to ECF with no change in Na concentration and no fluid redistribution. There are gains in the ECF due to gains in the blood resulting in increased BP - treatment for hypotension
what is a hypotonic solution gain?
water or dextrose - dilute patient - sodium decreases
what are the characteristics of gain of hypotonic solution?
greater gain to ICF, small decrease in sodium concentration, fluid redistribution between the ICF and ECF
why might a patient with a hypotonic gain show swelling or oedema?
the water goes into the cells and they swell
what causes hyponatraemia ?
dextrose drips have water in them - if confuse for sodium drip - kidneys need sodium to work and if not then will overload - patients can die of stroke
what does concentration of sodium in the blood depend on ?
water volume and redistribution
what is the result of sodium loss?
could be from diuretics - will lose Na in the ECF
what are the compensation mechanisms?
physiological or therapeutic