I. Pathophysiology

  1. Increased Total Body Water (TBW)
  2. Increased Total Body Sodium
  3. Increased Extracellular Fluid

II. Causes

  1. Hemodialysis
  2. Excessive intravenous Sodium administration
    1. Hypertonic Saline administration (3% saline)
    2. Sodium Bicarbonate infusions
    3. Replacing hypotonic insensible loss with 0.9% saline
  3. Mineralocorticoid excess
    1. Cushing Syndrome
      1. Consider 24-hour Urinary free cortisol level, Serum ACTH, Dexamethasone Suppression Test
    2. Hyperaldosteronism
      1. Presents with Hypertension and Hypokalemia
      2. Consider serum aldosterone to plasma renin activity ratio
  4. Excessive Salt intake
    1. Ingestion of salt tablets or salt water
    2. Saline enemas
    3. Enteral feeding

III. Management

  1. Discontinue hypertonic Sodium administration or other causative agents
  2. Consider evaluation for primary Hyperaldosteronism (if Hypokalemia, Hypertension)
  3. Administer Diuretics
  4. Free water replacement
    1. See Isovolemic Hypernatremia for protocol

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