hypo/hypernatremia Flashcards
osmolality
concentration of particles in a solution
tonicity
osmotic agents that cannot freely cross the cell membrane will result in water movement into or out of the cell
serum osmolarity formula
2[Na] + BUN /2.8 + glucose/18
hyponatremia serum sodium
<135 mEq/L
hyponatremia is due to
increased free water
appropriate response to hyponatremia should be ______ urine
dilute
appropriate response to hypernatremia should be ______ urine
concentrated
pseudohyponatremia
lab error due to hyperproteinemia or hypertriglyceridemia altering the plasma water concentration
isotonic
isotonic hyponatremia
low measured serum Na and normal serum osmolarity
hypotonic hyponatremia has ____serum Na and ____ serum osmolarity
low
low
hypertonic hyponatremia has ____serum Na and ____ serum osmolarity
low
high
(translocational hyponatremia)
translocational hyponatremia
reflects a movement of water from ICF to ECF due to hyperglycemia
(hypertonic hyponatremia)
after determining serum osmolarity, what is the next step in determining the cause of hyponatremia?
determine the patient’s volume status
the type of hyponatremia is determined by ____ and _____
serum osmolarity
volume status
clinically significant/true hyponatremia
hypotonic hyponatremia
hypotonic hyponatremia pathophys
excess of water compared to sodium in the ECF due to either dilution or depletion
hypovolemic hypotonic hyponatremia has ____ ECF volume
low
euvolemic hypotonic hyponatremia has ____ ECF volume
normal
hypervolemic hypotonic hyponatremia has ____ ECF volume
high
renal causes of hypovolemic hypotonic hyponatremia
diuretics
mineralocorticoid deficiency
extrarenal causes of hypovolemic hypotonic hyponatremia
diarrhea vomiting burns fever bleeding
renal causes of euvolemic hypotonic hyponatremia
SIADH post-op stress drugs glucocorticoid deficiency polydipsia tea and toast/beer potomania
tea and toast/beer potomania
reduced solute intake in the setting of normal or elevated free water intake
renal causes of hypervolemic hypotonic hyponatremia
acute or chronic kidney injury with low urine output
extrarenal causes of hypervolemic hypotonic hyponatremia
CHF
cirrhosis
nephrotic syndrome
urinary sodium concentration due to renal losses
> 20 mmol/L
urinary sodium concentration due to extra renal causes
< 20 mmol/L
hypovolemic hypotonic hyponatremia treatment
volume replacement with normal saline
euvolemic hypotonic hyponatremia treatment
water restriction
hypervolemic hypotonic hyponatremia treatment
volume removal with diuretics or water and Na restriction
most common cause of hyponatremia in hospitalized pts
SIADH
causes of SIADH
drugs
CNS lesions
pulmonary lesions
treatment for hyponatremia without symptoms
limit water intake to 1-1.5 L / day`
hypervolemia symptoms
peripheral and presacral edema
pulmonary edema
JVD
HTN
hypovolemia symptoms
poor skin turgor
dry mucous membranes
flat neck veins
hypotension
severe hyponatremia treatment
for Na <115
IV hypertonic saline
general clinical features of hyponatremia
confusion lethargy fatigue N/V cramps
symptoms of severe hyponatremia
*develops acutely
seizures
coma
respiratory failure
what is osmotic demyelination
damage to the myelin sheath due to a rapid correction of hyponatremia, typically involves the pons region
how much should sodium be raised per hour
0.5 mEq/L
possible severe sx of demyelination
nerve palsies
quadriplegia
locked in syndrome
hypernatremia definition based on sodium
increased serum sodium >145 mEq/L
hypernatremia is due to (general)
increased free water loss
hypertonic sodium gain
hypernatremia serum osmolality is always ______
increased resulting in a hypertonic state
in hypovolemic hypernatremia Na is ____ and ECF is _____
high
low
in euvolemic hypernatremia Na is ____ and ECF is _____
high
normal
in hypervolemic hypernatremia Na is ____ and ECF is _____
high
high
renal causes of hypovolemic hypernatremia
diuretics
postobstruction
intrinsic renal disease
when the cause of volume change is renal the serum Na is _____
> 20 mmol
extrarenal causes of hypovolemic hypernatremia
excess sweating
diarrhea
burns
fistulas
renal causes of euvolemic hypernatremia
diabetes insipidus
hypodipsia
renal causes of euvolemic hypernatremia
lack of access to/intake of water leads to oliguria
renal causes of hypervolemic hypernatremia
primary hyperaldosteronism
Cushings
hypernatremia symptoms
dehydration on PE thirst confusion lethargy muscle twitching vomiting
severe hypernatremia sx
seizures
coma
neuro defects
respiratory arrest
diabetes insipidus is due to
decreased or inefficient ADH = polyuria
when the cause of volume change is renal, the urinary Na is _____
<600 mOsm/kg
hypervolemic hypernatremia treatment
loop diuretics and free water replacement so that hypernatremia does not get worse
hypovolemic hypernatremia treatment
isotonic fluids to replete volume and then hypotonic fluids (D5W) to correct hypernatremia
diabetes insipidus treatment
desmopressin (synthetic ADH)
urine osmolality is ___ if extra renal loss , and urine is ___
increased, concentrated
urine osmolality is ___ if renal loss , and urine is ___
decreased
dilute
pure water and 5% dextrose in water are both
hypotonic fluids