Electrolyte Disorders

Electrolytes have various functions:
1. Maintenance of body pH
2. Cofactors in enzyme reactions
3. Water balance by maintaining osmotic
pressure
4. Correct functioning of muscles and nerves
5. Oxidation-reduction reactions

Osmolality - indicator of fluid balance:
- A measure of the osmotic concentration
usually expressed as moles of solute per kg of
solvent (mOsm/kg)
- 285 - 295 mOsm/kg

Regulation of fluid distribution:
1. Osmosis
a. Cells don't burst
b. 20-40% of the daily ATP generation consumed in trying to regulate ionic gradient
2. Maintaining electrical neutrality
a.
b. Expressed in mEq/L
c. Na+ 1 mmol/L = 1 mEq/L
d. Ca2+ 1 mmol/L = 2 mEq/L

Distribution of water in the body compartments: The body has 2 major fluid compartments:




Na+ regulates fluid flux between ECF and ICF
- Increase in Na+ ISF - H2O moves out from cells
- Decrease in Na+ ISF - cells overhydrate

, Loss of pure water from ECF:
- Ions can’t be exchanged to balance the difference
- Water movement will balance the difference




Renal regulation - juxtaglomerular apparatus