Flashcards in Electrolyte Homeostasis Deck (80)
What do U&E's measure? 6
Abnormal electrolytes can be the result of what 3 things?
1) Primary disease state
2) Secondary consequence of a multitude of diseases
3) Iatrogenic causes are common
Why are controlled electrolyte levels important? 4
1) Maintenance of cellular homeostasis
2) CV physiology
3) Renal physiology
4) Electrophysiology (heart, CNS)
Give 8 diseases that electrolyte imbalances are commonly seen in?
3) Poor intake - elderly
4) Increased losses -pyrexia
5) Diabetes insipidus
6) Diabetes mellitus
7) Diuretic therapy
8) Endocrine disorders
What is diabetes insipidus?
Rare form of diabetes caused by deficiency of the pituitary hormone vasopressin (ADH)
What are the 3 important components to think about when considering water and sodium balance?
1) Sodium in, sodium out
2) Water in and water out
3) Redistribution from cells into the extracellular compartment
You are trying to figure out what the intracellular concentrations are likely to be when you are only measuring the blood
What is the normal ECF amount and ICF amount?
ECF = plasma + interstitial fluid - 19L
ICF - 23L
What is the normal extracellular [Na]?
What will happen if you decrease the bodies total fluid level by 4L?
You will lose some fluid from ECF and some fluid from ICF, this will increase the concentrations of any solute
What will happen if you increase the bodies solute excretion to concentrations of electrolytes?
Concentration of all solutes in ECF and ICF will decrease
How much of the 19L of ECF is vascular and how much is interstitial?
3L vascular, 16L intersitial
What is the bodies total fluid content?
What is the normal extracellular [K]?
What is the normal intracellular [Na]?
What is the normal intracellular [K]?
Is the concentration of Na and K the same in plasma as in interstitial fluid, why?
Yes, solutes can move freely between so reach an equilibrium
What creates the membrane charges across the cell membrane?
Differences in [Na] and [K] between ECF and ICF
What is meant by an isotonic solution?
It has roughly the same conc of solutes as the blood
Give an example of loss of isotonic solution?
What happens to electrolytes and fluid levels in the body with a loss of 2L of isotonic solution?
Loss of 2L of isotonic solution and thus fluid from the ECF and no loss of fluid from the ICF
This is because the loss is isotonic so there is no change to [Na] and thus no fluid redistribution
Give an example of loss of hypotonic solution?
Dehydration from vomiting
What is meant by hypotonic solution?
Solution with a lower conc of electrolytes
What happens to electrolyte and fluid levels in the body with a loss of 3L of hypotonic solution ie. insensible loss?
Loss of fluid from ECF (1L) and ICF (2L) with more being lost from the ICF
Small increase in [Na] in the ECF and thus fluid redistribution between the ECF and ICF
Give and example of gain of isotonic solution?
What happens to electrolyte levels and fluid levels when there is a gain of 2L of isotonic solution?
Gain of 2L of fluid to ECF only, no change to ICF
No change in [Na]
No fluid redistribution (as gain is of isotonic solution)
Give an example of gain of hypotonic solution?
Water or dextrose administered
What would happen to fluid and electrolyte levels with a gain of 3L of hypotonic solution?
Gain of fluid to ICF and ECF with a greater gain to ECF
Small decrease in [Na] in ECF
Hence fluid redistribution between ECF and ICF
Give 3 examples of physiological compensatory mechanisms for changes to fluid and electrolyte levels?
Give 3 examples of therapeutic compensatory mechanisms for changes to fluid or electrolyte levels?
1) IV therapy