Water and Electrolyte Balance Quiz

Water and Electrolyte Balance

• The volume of the extracellular fluid (ECF) depends on the total body sodium content.
• Sodium is primarily found in the ECF.
• Water intake and loss are regulated to maintain a stable ECF osmolality and sodium concentration.
• Sodium balance is maintained by renal excretion regulation.

Hyponatremia

• Defined as a decreased plasma sodium concentration below 135 mmol/L.
• Often presents with no clinical evidence of volume depletion or edema.
• Occurs in patients with normal renal, adrenal, and thyroid function.

Management of Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

• Water intake restriction is crucial.
• Hypertonic saline administration carries the risk of fluid overload, potentially leading to pulmonary edema.
• Gradual sodium correction is essential for chronic dilutional hyponatremia to avoid central pontine myelinolysis.
• Addressing the underlying cause is vital.

Hypernatremia

• Defined as a plasma sodium concentration exceeding 145 mmol/L.
• Always hyperosmolar and less common than hyponatremia.
• Frequently observed in critically ill patients who may have difficulty drinking water.
• Neurologic symptoms are prominent due to neuronal cell water loss to the ECF, including tremors, irritability, ataxia, confusion, and coma.

Diabetes Insipidus (DI)

• Characterized by dilute urine with a low osmolality.