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Hyponatremia: Management


- Discussion:
    - determine volume status of the patient;
SIADH (Normovolemic)
          - Volume Excess Hyponatremia
          - Volume Depleted Hyponatremia;
                  - may be seen endurance athletes, military, and marathoners after prolonged exertion;
                  - due to excess free water intake that fails to replete massive sodium losses that result from sweating;
                  - exercise-induced hyponatremia is generally asymptomatic;
                  - usually symptoms arise when sodium level falls below 125 mEq/L;
                  - fluid balance should be maintained with sports beverages (which have 4-8% carbohydrates) 
                  - oral rehydration with salty solutions is safe and effective in patients with mild symptoms;
                  - references:
                         - Hyponatremia among Runners in the Boston Marathon
                         - Exercise-induced hyponatremia: causes, risks, prevention, and management.
                         - Hyponatremia in distance runners: fluid and sodium balance during exercise.

- Treatment:
    - if the patient has Normal ECF volume, SIADH, psuedohyponatremia, or endocrine d/o (hypothyroidism) should be considered;
    - many hyponatremic states are asymptomatic until the serum sodium level falls well below 120 mEq per liter;
    - one exception is the patient w/ increased CSF pressure, (as following closed head injury), in which mild hyponatremia may be extremely deleterious, even fatal;
            - this is due to the progressive increase in intracellular water (further increaseing intracranial pressure) as the extracellular fluid osmolarity falls);
    - complications:
            - brainstem herniation: requires rapid correction;
            - central pontine myelinolysis: occurs from too rapid correction;
            - ref: Myelinolysis after correction of hyponatremia


Hyponatremia and syndrome of inappropriate antidiuretic hormone secretion in adult spinal surgery.                                                  

Prevalence, Timing, Causes, and Outcomes of Hyponatremia in Hospitalized Orthopaedic Surgery Patients

Post-operative hyponatraemia in orthopaedic injury.

Hyponatremia at admission is associated with in-hospital death in patients with hip fracture