II. Pathophysiology
- Deficient response by Kidney to Antidiuretic Hormone (ADH)
- Contrast with Central Diabetes Insipidus (deficient ADH)
- ADH fails increasing collecting duct water permeability
- Failed countercurrent mechanism
- Inadequate generation of hypertonic interstitium
III. Causes
- Congenital
- Chronic disease of renal Medulla
- Medullary cystic disease
- Pyelonephritis
- Protein deficient diet
- Salt deficient diet
- Hypercalcemia
- Hypokalemia
- Amyloidosis
- Multiple Myeloma
- Medications
IV. Diagnosis
-
Fluid Deprivation Test
- No response to water deprivation
- No response to exogenous ADH administration
-
Hare-Hickey Test
- Increased ADH to Serum Osmolality ratio