III. Pathophysiology

  1. Excessive constant water diuresis due to:
    1. Central Anti-DiureticHormone deficiency (ADH) or
    2. Lack of renal response to Anti-DiureticHormone

IV. Symptoms

  1. Polyuria
  2. Polydipsia
    1. Unquenchable thirst

V. Differential Diagnosis

VI. Labs

VII. Diagnosis

  1. Fluid Deprivation Test
    1. Water deprivation
      1. No response in Nephrogenic DI or Central DI
    2. Exogenous ADH administration
      1. Corrects Central DI
      2. Does not correct Nephrogenic DI
  2. Hare-Hickey Test
    1. Fluid restriction or Injection of Hypertonic Saline
    2. Measure ADH to Serum Osmolality ratio
      1. Decreased ratio in Central Diabetes Insipidus
      2. Increased ratio in Nephrogenic Diabetes Insipidus

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