Electrolytes Flashcards
What are the predominant ions within ICF compartments?
K, Mg, PO4
What are the normal values of sodium, potassium, calcium, magnesium and phosphorus?
Na = 135-145 mEq/L K = 3.5 - 5.0 mEq/L Ca = 4.4 - 5.2 mEq/L Mg = 1.4 - 1.8 mEq/L Phos = 1.0 - 1.4 mmol/L
What are the functions of the predominant electrolytes Na, Cl, K, PO4, and Mg?
Na - helps nerve cells and muscle cells interact Cl - maintains osmotic pressure K - cell excitability PO4 - energy metabolism Mg - enzyme reactions
What is the osmolality calculation? What is the normal plasma osmolality range?
2[Na+] + [glucose]/18 + [BUN]/2.8
280-300 mOsm/kg
Note: inc osmolality = TBW DEPLETION
Note: dec osmolality = TBW EXCESS
What are the predominant ions within ECF compartments?
Na, Cl
What are the daily requirements of each: Na, K, Ca, Mg, Phos
Na: 1-2 mEq/kg K: 0.5-1 mEq/kg Ca: 800-1200mg Mg: 300-400 mg Phos: 800-1200 mg
What are the predominant ICF ions?
K
PO4
Mg
What is osmolality?
The measure of the number of osmotically-active particles per unit of solution
What substances are the common causes of osmolality gap?
The toxic alcohols: ethanol, methanol, ethylene glycol, isopropanol
Lorazepam
Mannitol
What is the treatment for hypertonic hyponatremia?
Treat this by treating the hyperglycemia. Na will return to normal.
What are the three categories of hypotonic huponatremia?
1) hypovolemic: deficit of both Na and TBW
2) euvolemic: normal Na, excess TBW
3) hypervolemic: excess of TBW and Na
What is the cutoff points for urine sodium levels in determining the causes of hyponatremia?
Na urine content 30 mEq/L means renal losses.
What is the treatment for Hypovolemic Hyponatremia?
Normal Saline
What is the treatment for Euvolemic Hyponatremia?
Fluid restriction (500-1000 mL/day) Hypertonic Saline (3% NS) if severe!
What most commonly causes Euvolemic Hyponatremia?
Anti-psychotics, SSRI's tumors stroke trauma carbamazepine
What is the treatment for hypervolemic hyponatremia?
Sodium and fluid restrictions (DASH diet)
Treatment of underlying disorder (loop diuretics, ACE-I, spironolactone)
What is the goal administration rate and target level?
0.5 - 1.0 mEq/hr to 125 mEq/L (low normal)
Why should we infuse NS slowly?
Fast admin (> 12 mEq/L in 24 hours and > 18 mEq/L in 48 hours) of NS can cause central pontine myelinolysis (irreversible paralysis)