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Hypernatremia
Aka: Hypernatremia, High serum sodium
DefinitionSerum Sodium exceeds 145 meq/liter
EpidemiologyIncidence : 1% of hospitalized elderly patients
PathophysiologyFree water deficient stateTotal Body Water deficit > Total Body Sodium Deficit Excess water loss or excess sodium retention Lacks normal physiologic response to free water lossInability to concentrate urine or inadequate ADH secretion Lack of thirst response or inadequate access to free water
Signs and SymptomsLethargy Restlessness Hyperreflexia Spasticity Seizure
CausesSee specific types below Hypernatremia with polyuria in hospitalized patients is commonResults from parenteral or enteral feeds and Increased free water lost or inadequate free water intake
Types: Based on Volume StatusHypervolemic Hypernatremia Hypernatremia with Increased Total Body Sodium Isovolemic Hypernatremia Hypernatremia with Normal Total Body Sodium Hypovolemic Hypernatremia Hypernatremia with Decreased Total Body Sodium
Labs (Dependent on Hypernatremia subtype as above)Serum labsSerum Glucose Serum Calcium Serum Creatinine and Blood Urea Nitrogen Urine labsUrine volume Urine Sodium Urine Potassium Urine Chloride Urine Calcium Calculations based on aboveSerum osmalality Serum to urine electrolyte ratioUrine electrolytes: Urine Sodium + Urine Potassium Serum electrolytes: Serum Sodium + Serum Potassium Interpretation (question whether Kidney is excreting or retaining electrolyte-free water)Concentrated urine: Urine electrolytes exceed serum electrolytes Dilute urine: Serum electrolytes exceed urine electrolytes
ManagementSee specific Hypernatremia types based on fluid status
Complications of cerebral dehydrationCerebral hemorrhageSubarachnoid Hemorrhage Subcortical hemorrhage Venous sinus thrombosis
Prognosis: MortalityChildrenAcute Hypernatremia: 43% Chronic Hypernatremia: 7-29% AdultsAcute Hypernatremia: 60%