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Hypernatremia

Causes of Hypernatremia                      Ref:  Outlines of Clinical Medicine

1. Dehydration - inadequate fluid intake to replace dermal, respiratory, or GI loss of fluid  
   Gastrointestinal causes: Vomiting or diarrhea or use of osmotic cathartic agents as lactulose; Nasogastric drainage; Enterocutaneous fistula; Tube feeding in semi conscious pt increased osmotic load 
   Cutaneous causes: Burns or excessive sweating  
2. Drugs:  Infusion of hypertonic Sodium salts, Hypertonic saline, Na-bicarbonate; hypertonic dialysis
3. Hyperaldosteronism, Cushing syndrome - rare causes
4. Diabetes Insipididus (DI)
   • Neurogenic diabetes insipidius: (Failure to make adequate ADH)
     • Post-traumatic
     • Caused by tumors, cysts, histiocytosis, TB, sarcoidosis
     • Idiopathic
     • Caused by aneurysms, meningitis, encephalitis, Guillain-Barre synd
     • Caused by ethanol ingestion (transient)
   • Acquired nephrogenic diabetes insipidus:  (Failure to respond to ADH)
     • Caused by renal disease (e.g. medullary cystic disease)
     • Caused by hypercalcemia or hypokalemia
     • Caused by drugs (lithium, demeclocycline, foscarnet, methoxyflurane, amphotericin B, vasopressin V2 receptor antagonists)
   • Congenital nephrogenic diabetes insipidus
5. Renal Failure (Inability to filter Na+) & Other Renal causes: Loop diuretics, Osmotic diuresis (glucose, urea, mannitol), Postobstructive diuresis, Polyuric , phase of acute tubular necrosis, Intrinsic renal disease
6. Coma (Disordered ADH regulation; absence of thirst mechanism)

2004