Sodium Imbalances Flashcards
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
In asymptomatic hyponatremia, treatment may be targeted to…
The underlying cause
Hypovolemic hyponatremia is treated with…
Isotonic saline - restore intravascular volume, decrease renal water retention (ADH off), and normalize serum sodium concentration
Hypervolemic hyponatremia is ideally treated by…
Manging underlying condition
Adminitration of fluid will worsen overload without changing serum sodium concentration
Diuretics (loops) may help attenuate hypervolemia
Euvolemic hyponatremia is ideally treated via ____. However, if not effective…
Identifying + correcting underlying causes.
Could try water restriction
Salt tablets, loop diuretics
Vasopressin antagonists
Hypernatremia is defined by sodium above ____.
145 mEq/L
Hypernatremia is a state of ____ leading to…
Hyperosmolality - cellular dehydration
Cells moving out of cells to follow sodium
Hypernatremia usually results from ____ rather than ____
Water deficit rather than net sodium gain
Normally. a hyperosmolar state will stimulate…
Compensatory mechanisms: thirst + excretion of a maximally concentrated urine
For hypernatremia to persist, one of both compensatory mechanisms must not be working, such as…
Impaired thirst response
Water loss in excess of electrolyte loss (significant diarrhea, osmotic diuresis, diabetes insipidus)
Diabetes insipidus is defined as…
Lack of secretion of ADH, or lack of renal response to ADH
NO water reabsorption - increasd thirst and increased urination
The presence and severity of hypernatremia symptoms depends on…
Both acuity and magnitude of hypernatremia
Severe/acute hypernatremia may present with…
Altered mental status
Weakness
Focal neurological deficits
Leading to coma, seizures, death
Hypernatremia needs to be treated SLOWLY because…
Over-aggressive correction can lead to brain cell swelling - seizures, permanent neurological damage, death
Body tries to adapt with sodium balance
In symptomatic hypernatremia, sodium levels should be corrected by no more than…
10-12 mEq/L per day
In chronic, compensated hypernatremia, sodium levels should be corrected even more slowly; no more than…
5-8 mEq/L per day
If a person with hypernatremia is also hypovolemic…
Extracellular fluid volume should be restored
Central diabetes insipidus treatment involves…
Desmopressin (synthetic analogue of vasopressin, ADH)
Titrated to achieve high-normal sodium concentration, stable urine output, and minimal nocturia
When starting desmopressin, this should be monitored…
Sodium levels - q1-3 days during initiation and titration, then ever 1-2 months
Watching for hyponatremia
Nephrogenic diabetes insipidus is treated via…
Thiazide diuretic + sodium restriction
Identifying and correcting concurrent hypercalcemia and hypokalemia
Sodium overloadis usually iatrogenic. In this case we would…
Administer D5W and loop diuretic to facilitate sodium excretion
