Electrolytes

Electrolytes are ions (charged particles) that are found within various parts of the body. They are responsible for a variety of processes in the body, including metabolism. Common electrolytes include sodium, potassium, chloride, magnesium, calcium, bicarbonate, and various metallic ions.

Common Electrolytes

Sodium

Sodium is absorbed by the small intestine, and primarily excreted by the kidneys. Its functions include:

• Maintaining osmotic strength of plasma
• Maintaining homeostasis by ion exchange
• Maintaining cell membrane permeability
• Acting as an impulse transmitter (nerves and muscles)

Hyponatremia

Causes various symptoms depending on serum levels. These include, GI symptoms, nausea, vomiting, weakness, headache, confusion/impairment, seizures, and coma. Low sodium levels can cause water to move into cellular compartments to maintain homeostasis, which can affect the CNS.

Pseudohyponatremia can be caused by sample hemolysis.

• Caused by loss of sodium from plasma, or excess gain of water
  • Renal sodium loss
    • Low aldosterone (adrenal insufficiency) = Addison's disease
    • Diuretics (increase urine excretion)
    • Increased vasopressin/ADH/AVP = Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
    • Kidney diseases
      • Polycystic kidney disease
      • Nephritis
    • Low serum potassium
      • Kidneys exchange sodium to conserve potassium
  • Extrarenal loss
    • Sweating
    • Mal-absorption
    • Vomiting or diarrhea
    • Burns
  • Increased water retention/intake

Hypernatremia

Hyperosmolar state with increased sodium. Can cause altered mental status, confusion, seizures, and coma.

• Excessive water loss/dehydration relative to sodium loss
• Sodium gain
• Decreased sodium excretion
  • Hyperaldosteronism, IV therapy, Cushing's syndrome
• Salt ingestion