Electrolyte imbalances

ELECTROLYTE IMBALANCES-CONCEPTS


Elecrolytes

  • Major concepts
    • Electrolyte concentrations in serum are the net result of:
      • intake
      • excretion
      • shifts between the ICF and ECF
      • must consider hydration state with [Na+] and [Cl-]

REPRESENTATIVE ELECTROLYTE CONCENTRATIONS

IN THE BODY FLUID COMPARTMENTS (mEg/L)
 

Electrolytes

Intracellular Fluid

Extracellular Fluid

Interstitial

ntravascular

Cations

-

-

-

-

Sodium

15

147

142

-

Potassium

155

4

5

5

Calcium

2

2.5

-

-

Magnesium

27

1

2

-

Anions

-

-

-

-

Bicarbonate

10

30

27

-

Chloride

1

114

103

-

Phosphate

100

2

2

-

Sulfate

20

1

1

-

Organic acids

1

7.5

-

5

Protein

62

0

16

-

  • Major functions of electrolytes
    • Na+
      • - H2O conservation (osmotic effect in kidney tubules)
      • As a measure of hydration status
      • hypothalmic osmoreceptors
      • renal volume receptors
    • Cl-
      • Gastric fluid (HCl)
      • linked to the renal generation of HCO3-

volume effects

  • hypovolemia - ↑ pituitary antidiuretic hormone (ADH)* → ↑ CT H2O resorption
  • hypervolemia - ↓ pituitary antidiuretic hormone (ADH)* → ↓ CT H2O resorption

Note : *at atrial and carotid baroreceptors (ADH)

  • hypoosmolality:
    • inhibit thirst centers → ↓ H2O intake
    • ↑ ADH* →  CT H2O resorption
  • hyperosmolality
    • stimulate thirst centers → ↑ H2O intake
    • ↑ ADH* → ↑ CT H2O resorption

Note : * at hypothalmic osmoreceptors
Last modified: Monday, 28 May 2012, 6:14 AM