Electrolytes & Fluids - Hypo- & Hyper-Natremia

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Snooze
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293114
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Electrolytes & Fluids - Hypo- & Hyper-Natremia
Updated:
2015-01-15 19:47:19
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Fluids
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Hypo and Hypernatremia
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  1. At what serum Na level would there be a correlation in reduction of plasma osmolality (and thus causing hypoNa and cell swelling)?
    Na<136mEq/L
  2. Explain what occurs with BOTH fluid and Na for each:
    Hypervolemic HypoNatremia
    Normovolemic HypoNatremia
    Hypovolemic HypoNatremia
    Hypervolemic HypoNatremia: Both fluid and serum Na are elevated, but fluid volume is in more excess

    Normovolemic HypoNatremia: Excess fluid volume with normal total body Na

    Hypovolemic HypoNatremia: Deficit of both fluid volume and Na, but total Na is decreased more-so than fluid
  3. What are common causes of:
    Hypervolemic HypoNatremia (3)
    Normovolemic HypoNatremia
    Hypovolemic HypoNatremia (3)
    Hypervolemic HypoNatremia: HF, cirrhosis, nephrotic syndrome

    Normovolemic HypoNatremia: SIADH

    Hypovolemic HypoNatremia: Fluid loss (from emesis, diarrhea, fever), 3rd-spacing, renal loss (diuretics)
  4. For Hypervolemic HypoNatremia and Hypovolemic HypoNatremia, what are their separate diagnostic labs? What does each range mean? (2 each)
    Hypervolemic HypoNatremia: Urine Na<25mEq/L indicates edematous disorders (HF, cirrhosis...); Urine Na>25 indicates acute/chronic renal failure

    Hypovolemic HypoNatremia: Urine Na<25mEq/L indicates nonrenal loss of Na (emesis, diarrhea); Na>40mEq/L indicates renal loss of Na
  5. How does one diagnose normovolemic HypoNatremia? (2)
    • Urine osmolality >100mOsm/kg
    • Urine Na>40mEq/L
  6. What are 3 general treatments for hypervolemic hyponatremia?
    • Na and H2O restriction
    • Treat underlying cause
    • Vasopressin receptor antagonists (conivaptan (Vaprisol), tolvaptan (Samsca))
  7. What is the general tx for hypovolemic hypoNatremia?
    Fluid resuscitation
  8. What are the general treatment options for normovolemic hyponatremia? (4)
    • If drug-induced SIADH, remove offending agent
    • Fluid restriction
    • Demeclocycline PO (FYI inhibits action of ADH in pt with SIADH, onset 2-5 days)
    • Vasopressin receptor antagonists (conivaptan (Vaprisol), tolvaptan (Samsca))
  9. What are 2 possible causes of pseudohyponatremia, which causes an increase in plasma osmolality?
    • Severe hyperlipidemia
    • Severe hyperglycemia (during DKA)
    • (So treat underlying condition!!)
  10. What are the four general causes of hyponatremia?
    • 1. Loss of isotonic fluid via vomiting/diarrhea is replaced by water (or post-op admin of hypotonic fluid)
    • 2. Secretion of ADH by certain conditions
    • 3. Med-induced
    • 4. Renal failure (impairs ability to excrete dilute urine)
  11. What are 4 reasons for the body to secrete ADH, thereby possibly causing hyponatremia?
    • 1. Volume depletion
    • 2. Organ hypoperfusion
    • 3. SIADH
    • 4. Cortisol defiiciency
  12. What are 4 general medication classes that may cause hyponatremia, especially in the elderly and those drink large amounts of water?
    • 1. TZD's
    • 2. CBZ, OXC
    • 3. SSRI's
    • 4. TCA's
  13. At what serum Na level can one experience serious manifestations of delirium, seizures, coma, resp arrest, or death?
    Na<115mEq/L
  14. For both hypo AND hypernatremia, what is the term that prevents cerebral cell swelling by causing osmotic shifts into/out of brain cells (and which may be the reason that severe cases may show no symptoms)?
    Osmotic adaptation
  15. What are the FIRST and SECOND line tx options for hyponatremia?
    1st line: Fluid restriction to 800ml/day

    2nd line: Vasopressin receptor antagonists (conivaptan (Vaprisol), PO tolvaptan (Samsca))
  16. When using conivaptan IV or tolvaptan PO, what are 3 things that one must watch out for?
    1. Monitor for DDI's with other 3A4 inhibitors that may increase serum Na (they are both 3A4 substrates and inhibitors)

    2. In the 1st 24hrs, do not restrict fluids d/t overly rapid changes in serum Na (FYI can restrict after 24hrs)

    3. Tolvaptan PO (Samsca) should NOT be administered for >30d to dec risk of liver injury
  17. What occurs in the body if there is intravascular volume depletion that is not treated?
    Continual secretion of ADH causing water reabsorption and hypoNa
  18. Volume status may be assessed by what 3 objective methods?
    • Skin turgor
    • Jugular venous pressure
    • Urine Na
  19. At what serum Na level would cause hyperosmolality and thus hyperNatremia?
    Na>145mEq/L
  20. What are two general causes of hypernatremia?
    • 1. Loss of water d/t fever, burns, infection, renal loss (diabetes insipidus), GI loss
    • 2. Retention of Na b/c of admin of HS
  21. What are two bodily responses that may help one prevent hypernatremia?
    • 1. Secretion of ADH
    • 2. Thirst
  22. At what serum Na level would one start to experience twitching, seizures, coma, or death with hypernatremia?
    Na>158mEq/L
  23. What is the max change in serum Na in 24 hours for symptomatic hypernatremia, which may prevent cerebral edema, etc?
    Same as with hyponatremia, NMT change of Na 12mEq/L in 24 hours
  24. What are the 4 treatment options for hypernatremia?
    1. PO water or IV D5W

    2. If both water and Na depletion, may use D5W and quarter NS

    3. If dec BP b/c of vol depletion, restore intravascular vol w/ NS to restore tissue perfusion

    4. If pt has severe diabetes insipidus may need desmopressin to replace insufficient absent ADH

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