Electrolyte Disorders Flashcards
What is the normal serum osmolality
280-295mOsm/kg
what is Osmolality
concentration of all particles in water (body fluid)
what is tonicity
osmotic pressure caused by particle restriction to one side of the cell membrane
what are the values of isotonic
280 - 295 mOsm/kg
what are the values of hypotonicity
<280 mOsm/kg
what are the values of hypertonicity
> 300 mOsm/kg
what is normal sodium levels
135-145 mEq/L
what is sodiums function in the human body
conduct nerve impulses
contraction of muscles
tonicity
what is the concentration of hypnatremia
<135 mEq/L
what is most hyponatremia secondary to
dilution, not low total sodium
what are the three types of hyponatremia
isotonic hyponatremia
hypotonic hyponatremia
hypertonic hyponatremia
what is another name for isotonic hyponatremia
psuedohyponatremia
what are common causes of isotonic hyponatremia
elevated triglycerides
elevated LDL
Hyperproteinemia from Multiple Myeloma
what is the treatment of isotonic hyponatremia
treat hypertriglyceridemia and/or LDL
-statin, fibrates, niacin, fish oil
Multiple Myeloma
- immunotherapy
What is another name for hypertonic hyponatremia
translational hyponatremia
what is hypertonic hyponatremia
hyponatremia (< 135) with high osmolality (>280-295)
what is hypotonic hyponatremia defined as
serum sodium < 135 and low serum osmolality < 280
how is hypotonic hyponatremia further classified
by volume status:
-hypovolemia hypotonic hyponatremia
- euvolemic hypotonic hyponatremia
- hypervolemic hypotonic hyponatremia
what is hypovolemic hypotonic hyponatremia
result of renal or extra renal volume loss with hypotonic fluid replacement
ADH stimulated to maintain intravascular volume
what are the causes of hypovolemic hypotonic hyponatremia
extra renal salt loss: dehydration, diarrhea, vomiting
renal salt loss: diuretics, ACEIs, kidney disease, mineralocorticoid (aldosterone) deficiency, cerebral salt wasting
What is euvolemic hypotonic hyponatremia primarily related to
ADH dysfunction or free water replacement of losses
what are the causes of euvolemic hypotonic hyponatremia
wide range:
adrenal insufficiency
SIADH
Hypothyroidism
thiazide diuretics
NSAIDs
ACEIs
etc.
what is hypervolemic hypotonic hyponatremia
related to edema and third spacing
reduced intra-vascular volume - ADH secretion in attempt to maintain
results in retention of free water, fluid overload, dilutional hyponatremia
what are causes of hypervolemic hypotonic hyponatremia
cirrhosis
heart failure
nephrotic syndrome
advanced kidney disease (impaired in water excretion)
what are severe symptoms of hyponatremia
seizure, coma, respiratory arrest
what are mild to moderate symptoms of hpyonatremia
headache, fatigue, lethargy, N/V, dizziness, ataxia, confusion and muscle cramps
what labs should be ordered for hyponatremia
serum electrolytes (CMP/CMP)
Creatinine
serum osmolality
urine osmolality
- thyroid function, LFTs, adrenal function testing
what are signs of hypovolemia
diminished BP and pulses
tachycardia
decreased skin turgor
what are the signs of hypervolemia
JVP
edema
orthopnea
what iis the treatment of hypotonic hyponatremia
restriction of free water or hypotonic solutions
what is the reatement of hypovolemic hypotonic hyponatremia
volume resuscitation
isotonic fluids: LR or normal saline
what is the treatment of hypervolemic hypotonic hyponatremia
reduce volume
diuresis with loops, dialysis or both
What is the treatment of isotonic hyponatremia
treat underlying cause: lower cholesterol, tx other protein pathologies
check lab for potential lab errors
what is the treatment of hypertonic hyponatremia
correct glucose: insulin, isotonic fluid:NS
discontinue any offending agents: mannitol, osmotic laxatives
when do you admit patients with hyponatremia for treatment
symptomatic patients or severe hyponatremia
what is the risk of rapid correction of hyponatremia
osmotic demyelination syndrome (ODS)
What is osmotic demyelination syndrome (ODS)
rapid rise in sodium concentration pulls water from the brain
results in cerebral demyelination (can occur outside the pons)
symptoms are progressive and often irreversible
what are symptoms of ODS
AMS
weakness or paryalysis in arms and legs
stiffness
impaired sensation
difficulty with coordination
coma
“locked in” syndrome
death
what is the treatment of ODS
supportive care
IV NS/5% dextrose
DDAVP
Plasmapheresis (?)
what are the different types of hypernatremia
always hyperosmolar state
hypovolemic - loss of TBW»_space; sodium
euvolemic - free water deficit
hypervolemic - pure sodium increase (and water follows)
what are the primary causes of hypernatremia
free water loss
hospitalized/institutionalized pt without free water access
excess sodium intake (rare)
primary hyperaldosteronism (usu mild and asymp)
what are symptoms of hypernatremia
signs of dehydration: orthostasis, oliguira
lethargy, irritability, weakness are early signs
hyperthermia, delirium, seizures, coma if severe
sodium > 185
what test can be used to help identify cause of water losses
Fractional excretion of sodium FENa
what is the treatment of hypernatremia
admit symptomatic pts
correct any cause of fluid loss
hypovolemia - isotonic NS fluid
Euvolemia- D5W - excretion of excess sodium in urine
hypervolemia - D5W + diuretics
what is normal potassium levels
3.5 to 4.5 mEq/L
what is the function of potassium in the human body
maintain ICF
maintain electrochemical gradient
muscle contraction
balance of pH
nerve signal transmission
cardiac refractory period
what is the lab volume that indicates hypokalemia
serum potassium < 3.5 mEq/L
what can hypokalemia be due to
inadequate intake
movement of K+ from ECF -> ICF
extra-renal K+ losses
Renal K+ losses
what are causes of extrarenal K+ losses
diarrhea, vomiting, laxative abuse, Zollinger-Ellison syndrome, villous adenoma
what are causes of Renal K+ losses
aldosterone, loop diuretics, Cushings syndrome, renin-producing tumor
dependent on Mg+ movements
what are symptoms of Hypokalemia
muscular weakness, fatigue, muscle cramping
constipation or ileus
if severe: flaccid paralysis, hyporeflexia, hypercapnia, tetany, rhabdomylosis
what diagnostic test can help ID causes of K+ losses
urinary potassium concentration
< 20 mEq/L = extrarenal losses
> 40 mEq/L = renal losses
what can be seen on EKG with hypokalemia
broadening of T waves
prominent U waves
PVCs
depressed ST segments
what is the treatment of hypokalemia
oral supplementation (dietary/diuretic associated losses)
IV potassium repletion (if severe)
what is the value for hyperkalemia
Potassium level > 5 mEq/L
what are causes of hyperkalemia
decreased K+ excretion (renal disease)
shift of K+ from ICF- ECF
excessive K+ intake
pseudo-hyperkalemia
what are the signs/symptoms off hyperkalemia
muscle weakness
urine, oliguria, anuria
respiratory distress
Decreased cardiac contractility
ECG changes
Reflexes, hyperreflexia or areflexia (flaccid)
what can you see on EKG with Hyperkalemia
Bradycardia
prolonged PR interval
Peaked T waves
QRS widening
Biphasic QRS complex
what is the treatment of hyperkalemia
withhold exogenous K+
ID and treat underling cause
correction of hyperkalemia: shift K+ back to ICF, remove K+ from body, dialysis
what is a hyperkalemic emergency
muscle weakness/paralysis
EKG changes
and/or
serum potassium > 6.5mEq/L
what is the treatment of a hyperkalemic emergency
calcium
insulin, sodium bicarbonate, albuterol
hemodialysis if due to renal disease/severe symptoms/serum K
potassium binding medications
Diuretics
What are potassium bidning medicatiosn
SCZ (Lokelma)
Patriomer (veltassa)
what are the complications of hypotonic fluid
cell lysis - dont give wiht blood products
diluation hyponatremia if prone to water retention
risk of elevated ICP
can exacerbate hypotension and hypovolemia
what are the indications for hypertonic fluid
Hyponatremia (NaCl)
when we need calories too
osmotic diuresis
hypoglycemia
what are the complications of Hypertonic fluid
ICF - intravascular and interstitial
-fluid overload
pulmonary edema (3rd spacing)
hyperglycemia if includes dextrose
