Extracellular fluid contains sodium for the maintenance of normal osmotic pressure and water balance. Approximately 50% of the body’s sodium is present in the extracellular fluid, 40% in bones and 10% or less in intracellular fluid.

    • Sodium along with chloride is major constituent in the extracelluar fluid. It is responsible to maintain osmotic pressure.
    • Acid and base balance is regulated by sodium. Sodium along with calcium, magnesium and potassium are basic in reaction; but chloride with phosphate and sulphate are acidic in reaction. Thus, acid-base balance is maintained
    • Sodium is concerned in the maintenance of water balance, muscle irritability contraction of muscles.
    • It regulates permeability of cell membrane
    • Maintenance of heart beat
    • It contributes alkalinity to the gastro-intestinal secretions.

    • Sodium deficiency occurs when the intake is poor or excessive amount is lost.
    • Sodium loss through excessive sweating causes deficiency unless salt intake is not increased.
    • Vomiting, severe diarrhoea, Addison’s disease is also responsible for sodium deficiency.
    • There is giddiness, cramps in muscles, collapsed veins, low blood pressure, dryness of mouth, inelastic skin and oliguria.

    Excess of Sodium
    • Any excess of sodium in the body accumulates in the extra cellular fluids.
    • The increased concentration of sodium is partially offset by an increase in these fluids.
    • Sodium excess may result in oedema.
    • In some the kidneys are enlarged and glomerulo nephritis may occur.
    • Persons consuming 10-25 gm of salt have been found to have a high incidence of raised blood pressure.


    • Adult - 500 mg
    • Children - 58 mg/day
    • Infants - 2.5 mmol/day

Last modified: Saturday, 2 June 2012, 6:29 AM