Sodium Imbalances Flashcards
(44 cards)
Both hypo + hypernatremia are disorders of…
Water balance or water distribution
Sodium imbalance is due to both an…
Initial challenge to water balance, as well as a failure of adaptive responses to compensate for this
Lab value of hyponatremia is usually…
Serum sodium < 135 mEq/L
Ingestion of too much “free” water causing hyponatremia is very rare, because…
A lot of water must be consumed to overwhelm the kidney’s ability to excrete it
Usually in combination with a solute-poor diet
Hyperosmolar hyponatremia occurs when…
An osmotically active agent, other than sodium accumulates in the extracellular fluid, drawing water into extracellular fluid and diluting sodium
Actual sodium content is normal but the concentration of sodium in water is reduced (dilutional hyponatremia)
Hyperosmolar hyponatremia is most commonly due to…
Hyperglycemia - excessive blood glucose draws water from inside cells to outside cells and dilutes sodium
Treat hyperglycemia since sodium is normal
Hypovolemia hyponatremia results from
Net sodium loss
Hypovolemia hyponatremia may be caused by…
Thiazide diuretics
Loop diuretics
Increased age and females are more vulnerable
Hypervolemic hyponatremia occurs during…
Fluid-overloaded states (HF, cirrhosis with ascites, severe nephrotic syndrome) - fluid shifts from intravascular to interstitial space
Dilutional hyponatremia
Euvolemic hyponatremia is caused by…
Activation of water-conserving mechanisms (ADH)
In euvolemic hyponatremia, renal response to volume remains intact so patients are generally euvolemic. However, due to increased total body water…
Serum sodium concentration is decreased
The most common form of euvolemic hyponatremia is…
Syndrome of Inappropriate Antidiuretic Hormone secretion (SIADH)
Non-physiological release of ADH - too much = reabsorption of free water leading to diluting sodium
SIADH may be caused by…
Neurologic or psychiatric disorders
Pulmonary diseases
Malignant tumors
Drugs - SSRI’s, antipsychotics, narcotics, NSAID’s
Chronic hyponatremia is usually…
Relatively asymptomatic - body compensates
Often detected on routine bloodwork
While chronic hyponatremia is relatively asymptomatic, it has been associated with…
Impaired attention, concentration, and gait - increased fall risk
Acute hyponatremia symptoms are primarily…
Neurologic; nausea, malaise, fatigue, leading to seizures, altered consciousness, coma, death
Osmotic intracellular water shift - dehydrating cells
Symptoms of hyponatremia are proportional to…
The magnitude and rapidity of sodium decline
Symptoms may manifest with hyponatremia at this lab value…
~125 mEq/L
Severe hyponatremia symptoms may manifest at these lab values…
~115 mEq/L
Diagnosis of hyponatremia is primarily via…
Plasma osmolality
Urine osmolality
Urine sodium concentration
These will generally be low; if not, need to look at etiology
It is VERY important to correct hyponatremia slowly because…
Cells gradually adapt to the hyponatremic state + overly rapid correction can lead to rapid cell shrinkage and brain damage
Total daily sodium correction in hyponatremia should NOT exceed…
8 mEq per day
This can be given to correct majority of hyponatremia cases…
Hypertonic saline - bolus or infusion
Frequent sodium rechecks are necessary in order to…
Ensure appropriate correction + adjust strategy as needed
