Lecture 2 - Electrolytes Hyponatremia

Question 1

Na Range

Answer 1

135-145 mEq/L

Question 2

Sodium (135-145 mEq/L)

• primary ___ cation
• needed to maintain cellular ___
• maintains osmolar gradient which regulates fluid ___ throughout the diff compartments

Answer 2

• extracellular
• integrity
• homeostasis

Question 3

Hyponatremia

• most ___ and complicated disturbace
• too rapid correction of Na results in ___
• ___ injury
• acute effects of hypo-osmolarity
• significant morbidity and mortality

Answer 3

• common
• demyelination
• brain

Question 4

Na level less than ___ is considered hyponatremia

Answer 4

Na < 135 mEq/L

Question 5

Osmolality (275-290 mOsm/L)

• number of ___ per L of water

Answer 5

particles

Question 6

serum Osm calculation should predict the measured serum osm within ___ mOsm/L

Answer 6

5-10 mOsm/L

Question 7

Example Serum Osm Calculation

Osm = (2 x Na) + (BUN/2.8) + (glucose/18)

Actual serum Osm = 322 mOsm/L

Answer 7

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

Question 8

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)

Answer 8

• hypertriglyceridemia, hyperproteinemia
• displaced
• measured
• calculated

Calculated is low but measued isn’t affected

Question 9

Hypertonic Hyponatremia

Na is low, what is making this hypertonic?

What is the calc Osm?

Answer 9

glucose is 6x normal level

(2 x 128) + (50/2.8) + (600/18) = 307 mOsm/L

Question 10

Hypertonic Hyponatremia - Corrected Serum Na

What is the corrected Na?

Corrected Na+ = Na serum + 1.6[(BG-100)/100]

Answer 10

128 + 1.6[(600-100)/100] = 136 mEq/L

Question 11

Hypotonic Hyponatremia

• > ___ of all hyponatremia
• most important step is to clincally assess the pt’s ___ volume
• hypovolemic, isovolemic, hypervolemic

Answer 11

• 90%
• ECF

Question 12

often the sickest patients are ___ volemic, ___ tonic, ___ natremic

Answer 12

hypo, hypo, hypo

need fluid and Na

Question 13

Hypovolemic Hypotonic Hyponatremic

decrease in both ___ and ___
___ causes (urine Na > 20 mEq/L)
- ___ /excessive diuresis
- adrenal insufficiency ( ___ deficiency)
- salt losing nephropathy
- ___ salt wasting

Answer 13

total body water and Na
renal
- diuretics
- mineralcorticoid
- cerebral

pt is typically on diuretic
hormonal or CNS disorder

Question 14

Hypovolemic Hypotonic Hyponatremic

T or F: if urine Na is low (urine Na < 20 mEq/L), it’s a renal cause

Answer 14

F; non-renal

if you are peeing out a lot of Na it’s renal

Question 15

Hypovolemic Hypotonic Hyponatremic

___ causes (urine Na < 20 mEq)
- blood loss/hemorrhage
- skin losses (burns, sweat, wounds)
- GI losses (vomiting, diarrhea, suction)

Answer 15

non-renal

Question 16

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 ( ___ )

Answer 16

Na
- ECF
- euvolemic
- glucocorticoid
- hypothyroidism
- syndrome of inappropriate antidiuretic hormone release

Question 17

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

Answer 17

• exceeds
• 100
• 20-30
• drugs

Question 18

Possible Drug-induced SIADH

Answer 18

• antipsychotics
• carbamazepine
• SSRIs (fluoxetine and sertraline)

Question 19

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:

Answer 19

• medications
• free water
• Vaptans, “aquaretics”
• Conivaptan and Tolvaptan

Question 20

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

Answer 20

• Na, TBW
• ECF, edema

Question 21

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

Answer 21

• 125
• dehydration
• edema

Question 22

Goals of Treatment

Hypovolemic
What do we want to do?

Answer 22

restore volume deficit

Question 23

Goals of Treatment

Isovolemic or Hypervolemic
What do we want to do?

Answer 23

• determine underlying cause
• is pt symptomatic?

dont want to add more volume if we dont have to (will mak worse)

Question 24

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

Answer 24

• 0.5
• 8-12

Question 25

# Treatment options Hypovolemic - ___ NaCl ( ___% NaCl) if symptomatic - ___ NaCl ( ___NaCl) if asymptomatic

Answer 25

* hypertonic, 3% * isotonic, 0.9%

Question 26

# Treatment options Isovolemic - ___ and ___ % NaCl if symptomatic - ___ NaCl and ___ restriction if asymptomatic

Answer 26

* furosemide, 3% * 0.9%, water

Question 27

# Treatment options Hypervolemic - ___ and judicious ___ NaCl if symptomatic - ___ in asymptomatic pts

Answer 27

- furosemide, 3% - furosemide

Question 28

# acute vs chronic hyponatriemia Acute - brain swells with ___ - ___ edema - ___ neurologic Sx - brain herniation - death

Answer 28

* water * brain * severe

Question 29

# acute vs chronic hyponatriemia Chronic - brain cells extrude ___ - minimal brain ___ - ___ neurologic Sx - brain herniation rare - death is rare

Answer 29

* solutes * swelling * mild

Question 30

# acute symptomatic hyponatremia Sx typically ___ related - altered mental status - seizures Metabolic encephalopathy can develop - cerebral ___ - increased intracranial pressure (ICP) - irreversible and sometimes fatal

Answer 30

* CNS * edema | prompt treatment needed

Question 31

# 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

Answer 31

1-2 * 120 * unecessary * demyelinating * 4-6 * 8-12 | CPM = central pontine myelinolysis

Question 32

T or F: risk of cerebral edema from hyponatremia far outweighs risk of demyelination from correcting too rapidly?

Answer 32

T | lesser of 2 evils

Question 33

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

Answer 33

* 105 * hypo * liver * 25

Question 34

# Rule of 8s replace half of Na deficit in 8 hrs, then remaining deficit within ___ hrs

Answer 34

8-16

Question 35

know how to calculate Na replacement

Answer 35

slides 95-98

Question 36

# 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

Answer 36

* 2-4 * 6-8

Question 37

# Vaptans Conivaptan (IV) and Tolvaptan (PO) - arginine vasopressin V2/V1A receptor ___ - promotes excretion of free ___ - no loss in serum ___ - normalized ___ levels - $$$

Answer 37

* antagonist * H2O * electrolytes * Na | basically a diuretic that doesnt drain electrolytes