PHRM 825: Fluids and Electrolytes - Electrolytes - Na+ Flashcards
Sodium goal concentration
135-145 mEq/L (remember 140)
Sodium is primarily an _______ cation
extracellular
Sodium is needed to maintain _______
cellular integrity
Sodium maintains ____ gradient and regulates ______ throughout the different compartments
Osmolar; fluid homeostasis
What is the most common electrolyte disturbance in hospitalized patients
Hyponatremia
Hyponatremia has significant ________
morbidity and mortality
Osmolarity calculation
Osm = (2*Na) + (BUN/2.8) + (Glucose/18)
Osmole gap (OG) exists when
The difference between the measured and calculated is greater than 15
OG is the presence of
Unidentified particles
Osmole gap calculation
Osm serum - Calculated Osm
Types of hyponatremia
Pseudohyponatremia, Hypertonic hyponatreamia, hypotonic hyponatremia
Types of hypotonic hyponatremia
Hypovolemic hyponatremia, isovolemic hyponatremia, hypervolemic hyponatremia
Pseudohyponatremia is ______
isotonic
Pseudohyponatremia definition
When extreme elevation of lipids and proteins increase the total plasma volume which leads to a dilution effect so the sodium appears low
Pseudohyponatremia calculated Osm is _____ which leads to an ____
Los; OG
Hypertonic hyponatremia is most frequently seen with _______
elevated blood glucose
Serum sodium falls by ______ for each _______ incremental increase in BG >______
1.6 mEq/L; 100mg/dL; 100 mg/dL
Equation for corrected sodium
Corrected Na+ = Na serum + 1.6[(BG-100)/100]
Hypotonic hyponatremia accounts for what percentage of all hyponatremias
> 90%
Most important step when assessing for hypotonic hyponatremia is to clinically assess the patient’s _____
ECF volume
Hypovolemic hypotonic hyponatremia is characterized by a decrease in both total body _____ and _____
Water and Na+
Renal causes of hypovolemic hypotonic hyponatremia
- Diuretics/excessive diuresis
- Adrenal insufficiency
- Salt losing nephropathy
- Cerebral salt wasting
When hypovolemic hypotonic hyponatremia is caused by the renal system, urine sodium levels will be ____
> 20 mEq/L
Non-renal causes of hypovolemic hypotonic hyponatremia
- Blood loss/hemorrhage
- Skin losses (burns, sweat, wounds)
- GI losses (vomiting, diarrhea, suction)
Causes of isovolemic hypotonic hyponatremia
- Adrenal insufficiency (glucocorticoid deficiency)
- Hypothyroidism
- Psychogenic polydipsia
- SIADH
Meaning of SIADH
Syndrome of Inappropriate Antidiuretic hormone release
What is the most common cause of isovolemic hypotonic hyponatremia
SIADH
Characteristics of SIADH
Water intake exceeds capacity of the kidneys to excrete water
Causes of SIADH
Tumors, CNS disorders (stroke, head trauma, meningitis, etc), Drugs
Usual urine Osm and Na+ in someone with SIADH
Osm > 100 mOsm/kg
Na > 20-30 mEq/L
How is SIADH treated?
- Remove underlying cause if possible
- First line: free H2O restriction
- Vaptans (if 24-48 hrs of free h2o restriction fails)
Hypervolemic hypotonic hyponatremia is caused when
The total body Na+ is increased but the TBW is increased even more