Lecture 2 - Electrolytes Hyponatremia Flashcards
Na Range
135-145 mEq/L
Sodium (135-145 mEq/L)
- primary ___ cation
- needed to maintain cellular ___
- maintains osmolar gradient which regulates fluid ___ throughout the diff compartments
- extracellular
- integrity
- homeostasis
Hyponatremia
- most ___ and complicated disturbace
- too rapid correction of Na results in ___
- ___ injury
- acute effects of hypo-osmolarity
- significant morbidity and mortality
- common
- demyelination
- brain
Na level less than ___ is considered hyponatremia
Na < 135 mEq/L
Osmolality (275-290 mOsm/L)
- number of ___ per L of water
particles
serum Osm calculation should predict the measured serum osm within ___ mOsm/L
5-10 mOsm/L
Example Serum Osm Calculation
Osm = (2 x Na) + (BUN/2.8) + (glucose/18)
Actual serum Osm = 322 mOsm/L
Osm = (2 x 145) + (10/2.8) + (90/18)
= 299 mOsm/L
since actual serum Osm is greater than 5-10 mOsm/L from what was calculated, we know theres some other substance in the blood
Pseudohyponatremia (Isotonic)
- extreme elevations of lipid and proteins increase the total plasma volume
- can be seen with ___ or ___
- leads to a dilution effect
- sodium appears low (it is still there, just ___ )
- ___ serum osmolality is not significantly affected
- ___ Osm is low (due to low sodium)
- Leads to an osmolality gap (OG)
- hypertriglyceridemia, hyperproteinemia
- displaced
- measured
- calculated
Calculated is low but measued isn’t affected
Hypertonic Hyponatremia
Na is low, what is making this hypertonic?
What is the calc Osm?
glucose is 6x normal level
(2 x 128) + (50/2.8) + (600/18) = 307 mOsm/L
Hypertonic Hyponatremia - Corrected Serum Na
What is the corrected Na?
Corrected Na+ = Na serum + 1.6[(BG-100)/100]
128 + 1.6[(600-100)/100] = 136 mEq/L
Hypotonic Hyponatremia
- > ___ of all hyponatremia
- most important step is to clincally assess the pt’s ___ volume
- hypovolemic, isovolemic, hypervolemic
- 90%
- ECF
often the sickest patients are ___ volemic, ___ tonic, ___ natremic
hypo, hypo, hypo
need fluid and Na
Hypovolemic Hypotonic Hyponatremic
decrease in both ___ and ___
___ causes (urine Na > 20 mEq/L)
- ___ /excessive diuresis
- adrenal insufficiency ( ___ deficiency)
- salt losing nephropathy
- ___ salt wasting
total body water and Na
renal
- diuretics
- mineralcorticoid
- cerebral
pt is typically on diuretic
hormonal or CNS disorder
Hypovolemic Hypotonic Hyponatremic
T or F: if urine Na is low (urine Na < 20 mEq/L), it’s a renal cause
F; non-renal
if you are peeing out a lot of Na it’s renal
Hypovolemic Hypotonic Hyponatremic
___ causes (urine Na < 20 mEq)
- blood loss/hemorrhage
- skin losses (burns, sweat, wounds)
- GI losses (vomiting, diarrhea, suction)
non-renal
Isovolemic Hypotonic Hyponatremia
raised TBW and normal/slightly raised total body ___
- slight excess of ___ fluid
- no edema
- clinically appears ___
causes
- adrenal insufficiency (___ deficiency)
- ___thyroidism
- psychogenic polydipsia
- SIADH ( ___ )
Na
- ECF
- euvolemic
- glucocorticoid
- hypothyroidism
- syndrome of inappropriate antidiuretic hormone release
SIADH
most common cause of isovolemic hypotonic hyponatremia
- water intake ___ capacity of kidneys to excrete water
- urine Osm generally > ___ mOsm/kg
- urine Na generally > ___ mEq/L
- causes: tumors, CNS disorders, ___
syndrome of inappropriate antidiuretic hormone release
- exceeds
- 100
- 20-30
- drugs
Possible Drug-induced SIADH
- antipsychotics
- carbamazepine
- SSRIs (fluoxetine and sertraline)
Treatment of SIADH
- remove underlying cause (most likely ___ )
- First line: ___ restriction
- __ may be benefcial if 24-48 hours of free water restriction fails (“___”)
- 2 examples:
- medications
- free water
- Vaptans, “aquaretics”
- Conivaptan and Tolvaptan
Hypervolemic Hypotonic Hyponatremia
- total body ___ is increased but ___ is increased even MORE
- expanded ___ fluid volume and ___
- seen with: cirrhosis, heart failure, kidney failure, nephrotic syndromes
- Na, TBW
- ECF, edema
clinical prsentation of hypotonic hyponatremia
mostly asymptomatic (Na > ___ mEq/L)
hypovolemic = ___
- decreased skin turgor, orthostatic hypotension, tachycardia, dry mucous membranes
isovolemic
- malaise, psychosos, seizures, coma
hypervolemic
- ___ and weight gain
acute hyponatremia
- nausea, malaise, weakness, headache, disorented, coma, seizures, respiratory arrest
- 125
- dehydration
- edema
Goals of Treatment
Hypovolemic
What do we want to do?
restore volume deficit
Goals of Treatment
Isovolemic or Hypervolemic
What do we want to do?
- determine underlying cause
- is pt symptomatic?
dont want to add more volume if we dont have to (will mak worse)
Goals of Treatment
in most cases the goal is to avoid rise in serum sodium > ___ mEq/L/hr or no more that ___ mEq/L/day
- 0.5
- 8-12
Treatment options
Hypovolemic
- ___ NaCl ( ___% NaCl) if symptomatic
- ___ NaCl ( ___NaCl) if asymptomatic
- hypertonic, 3%
- isotonic, 0.9%
Treatment options
Isovolemic
- ___ and ___ % NaCl if symptomatic
- ___ NaCl and ___ restriction if asymptomatic
- furosemide, 3%
- 0.9%, water
Treatment options
Hypervolemic
- ___ and judicious ___ NaCl if symptomatic
- ___ in asymptomatic pts
- furosemide, 3%
- furosemide
acute vs chronic hyponatriemia
Acute
- brain swells with ___
- ___ edema
- ___ neurologic Sx
- brain herniation
- death
- water
- brain
- severe
acute vs chronic hyponatriemia
Chronic
- brain cells extrude ___
- minimal brain ___
- ___ neurologic Sx
- brain herniation rare
- death is rare
- solutes
- swelling
- mild
acute symptomatic hyponatremia
Sx typically ___ related
- altered mental status
- seizures
Metabolic encephalopathy can develop
- cerebral ___
- increased intracranial pressure (ICP)
- irreversible and sometimes fatal
- CNS
- edema
prompt treatment needed
acute hyponatremia treatment
increase serum Na by ___ mEq/L/hr until symptoms resolve
- reasonable short term Na goal ___ mEq/L
- complete corretion is ___
- if corrected too rapidly, diffuse ___ lesions (CPM). Irreversibe.
- generally, an increase of ___ mEq/L is sufficient to reverse most acute manifestations
- MAX increase of ___ mEq/L in the first 24 hrs
1-2
* 120
* unecessary
* demyelinating
* 4-6
* 8-12
CPM = central pontine myelinolysis
T or F: risk of cerebral edema from hyponatremia far outweighs risk of demyelination from correcting too rapidly?
T
lesser of 2 evils
known demyelination risk factors:
- serum Na < ___ mEq/L
- ___kalemia
- alcohol use disorder
- malnutrition
- advanced ___ disease
potential risk factors:
- hypoxemia
- cancer
- severe burns
- diabetes
- renal faillure
- increase in Na exceeeding ___ mEq/L in 48 hrs
- 105
- hypo
- liver
- 25
Rule of 8s
replace half of Na deficit in 8 hrs, then remaining deficit within ___ hrs
8-16
know how to calculate Na replacement
slides 95-98
acute symptomatic hyponatremia monitoring
- heart, lungs, and neurologic status should be checked several times over first 12 hours
- check serum Na concentrations q ___ hrs until asymptomatic
- then check serum Na q ___ hrs until WNL
- 2-4
- 6-8
Vaptans
Conivaptan (IV) and Tolvaptan (PO)
- arginine vasopressin V2/V1A receptor ___
- promotes excretion of free ___
- no loss in serum ___
- normalized ___ levels
- $$$
- antagonist
- H2O
- electrolytes
- Na
basically a diuretic that doesnt drain electrolytes
