electrolyte disorders Flashcards
causes of hyperkalemia
cellular redistribution from the intracellular to the extracellular compartment
K++ retention
impaired K++ excretion
tissue breakdown
Hyperkalemia commonly associated with what
renal failure
ACE inh
hyporeninemic hypoaldosteronism
cell death
metabolic acidosis
severe hyperkalemia can result in what
dysrhythmias and cardiac arrest
what can cause spurious hyperkalemia
thrombocytosis and hemolysis
hypoaldosteroism and metabolic acidosis commonly assoc with what
hyperkalemia
earliest ECG manisfestation of hyperkalemia is what
(over 6.5)
peaking of T waves
ECG changes in severe hyperkalemia(over 7)
P wave flattening, PR interval prolongation, QRS widening
what to give in severe hyperkalemia with heart effects
calcium gluconate IV to antagonize effects of heart.
what can you give to drive K++ back into the intracellular compartment;
good/bad
sodium bicarb, glucose, insulin;
rapid onset but duration short
what to give to remove K++ from the body
kayexalate
last resort: hemodialysis
neurologic symptoms of hyperkalemia
numbness, tingling, weakness, flaccid paralysis
labs for hyperkalemia
serum K++ over 5
urine K++, Cr, osmolality reveal decreased fractional excretion of K++
EKG when K++ is 8-10
sine wave pattern with cardiac arrest
cellular redistribution from the intracellular to the extracellular compartment
K++ retention
impaired K++ excretion
tissue breakdown
causes of hyperkalemia
renal failure
ACE inh
hyporeninemic hypoaldosteronism
cell death
metabolic acidosis
Hyperkalemia commonly associated with what
P wave flattening, PR interval prolongation, QRS widening
ECG changes in severe hyperkalemia(over 7)
numbness, tingling, weakness, flaccid paralysis
neurologic symptoms of hyperkalemia
serum K++ over 5
urine K++, Cr, osmolality reveal decreased fractional excretion of K++
labs for hyperkalemia
pnemonic for hyperkalemia tx
C BIG BK
calcium gluconate
bicarb and/or insulin and glucose to temporarily shift K++ back into cells
B agonists to promote celluar reuptake of K++
Kayexalte to remove K++ from body
causes of hypokalemia
shift of K++ into intracellular compartment or from K++ losses of extrarenal or renal origin
most commonly occurs with diuretics, renal tubular acidosis, GI losses, hypomagnesemia, polyuria
vent arrhythmias, MI, ileus, constipation, rhabdomyolysis
think hypokalemia
ECG in hypokalemia
flattened or inverted T waves, prominent U waves, ST depression, ventricular ectopy
most helpful tests for causal workup of hypokalemia
blood acid-base parameters, urinary K++ and Cl levels
how does hypokalemia affect the heart
it potentiates the effects of cardiac glycosides on myocardial conduction and may lead to dig intoxication
cardiovascular manisfestations of hypokalemia
ventricular arrhythmias, hypoTN, cardiac arrest
neuromuscular manisfestations of hypokalemia
malaise, skeletal mm weakness, cramps, smooth mm involvement leading to ileus and constipation
polyuria, nocturia, hyperglycemia, rhabdomyolysis, ileus, cramps or weakness, hyporeflexia, ascending paralysis
hypokalemia
how to distinguish renal from GI losses on hypokalemia
24 hr or spot urine K++ test
If hypokalemia is not responding to K++ repletion, then what
check magnesium levels
shift of K++ into intracellular compartment or from K++ losses of extrarenal or renal origin
most commonly occurs with diuretics, renal tubular acidosis, GI losses, hypomagnesemia, polyuria
causes of hypokalemia
flattened or inverted T waves, prominent U waves, ST depression, ventricular ectopy
ECG in hypokalemia
it potentiates the effects of cardiac glycosides on myocardial conduction and may lead to dig intoxication
how does hypokalemia affect the heart
ventricular arrhythmias, hypoTN, cardiac arrest
cardiovascular manisfestations of hypokalemia
malaise, skeletal mm weakness, cramps, smooth mm involvement leading to ileus and constipation
neuromuscular manisfestations of hypokalemia
relationship between PTH, Ca, Phosphorus
PTH and Ca same, phosphorus different
hospitalized pt with malignancy
think hypercalcemia
anorexia, nausea, constipation, polyuria, polydipsia, consciousness level, inravascular volume depletion
hypercalcemia
24 hr urine calcium levels mean what
elevated: cancer or hyperparathyroidism. decreased: hyperparathyroidism
worst thing hypocalcemia can do
complete cardio collapse
psoriasis, dry skin, perioral numbness
CV signs: wheezing, bradycardia, crackles, S3
hypocalcemia signs
common causes of disorders of calcium and phosphorus
PTH d/o, chronic renal failure, malignancy
vitamin D intoxication, hyperparathyroidism, sarcoidosis
other causes of hypercalcemia
which calcium disorder is more common?
found in who?
hypocalcemia
critically ill pts
hypercalcemia
s/s
anorexia, nausea, constipation, polyuria, polydipsia, consciousness level, inravascular volume depletion
common causes of hypocalcemia
chr disease(like CKD) or hypoparathyroidism
what is trosseau’s sign
carpel tunnel spasm after BP cuff applied for 3 min. hypocalcemia
what is chvostek’s sign
spasm of facial muscle after tapping facial nn. hypocalcemia
severe hypocalcemia results in what
complete cardiovascular collapse
severe manisfestations: syncope and angina
brittle nails, pruritis, mm cramps, SOB, n/t in extremities
sx of hypocalcemia
hypocalcemia signs
psoriasis, dry skin, perioral numbness
CV signs: wheezing, bradycardia, crackles, S3
neuro findings in hypocalcemia
trousseau, chvostek, confusion, dementia, seizure, irritability
cramps and tetany after a thyroidectomy
hypocalcemia
labs for hypocalcemia
ionized Ca and PTH
corrected calcium formula
measured total calcium + [0.8 x (4-albumin)]
normal calcium levels
8.5 to 10.2
tests to order for hypercalcemia
corrected Ca
CXR to look for pulm mass
UA for hematuria- RCC
ESR
24 hr urine
hypercalcemia tx
isotonic saline for volume repletion
loop if hypervolemic after this
bisphosphonates for severe cases
vitamin D def, respiratory alkalosis, burns, hyperPTH
common causes of hypophosphatemia
hyperphosphatemia commonly secondary to what
CKD
hypophosphatemia commonly secondary to what
diminished supply or absorption, increased urinary losses or redistribution
severe hypophosphatemia may lead to what
rhabdo, paresthesia, encephalopathy
phosphate binders
calcium carbonate tablets
normal phosphate levels
2.5 to 4.5
normal magnesium levels
1.5 to 2.5
sx of hypermagnesemia
usually asymptomatic except in CKD given Mg products such as laxatives or antacids
decreased DTR, mm weakness, N/V, resp depression, then cardiac arrest follows
ECG findings in hypermagnesemia
widened QRS complex, prolonged PR interval, prolonged Q-T interval
bleeding and clotting times increased
think hypermagnesemia
tx of hypermagenesemia
calcium gluconate, lasix, dialysis
hypokalemia, hypocalcemia, hypocalciuria assoc with what
hypomag
most magnesium is stored where
bones and muscles
tx of hypomagnesemia
oral magnesium oxide for chronic cases
severe symptomatic: mag sulfate sol’n IV 7 days(1 gm then 6 days over 1 L in 24 hrs); or IM 4 doses
when does hypomag appear
when total body stores are severely depleted; usually from diminished intake and impaired absorption
what is hypomag commonly associated with
chronic alcoholism
chronic diarrhea
hypoPTH
hyperaldosteronism
diuretic therapy
osmotic diuresis
nutritional deficiencies
long term use of PPI
S/S of hypomag
tetany, N/V, lethargy, anorexia, weakness, seizures, weakness
labs and EKG for hypomag
hypokalemia, hypocalcemia, hypocalciuria
EKG: prolonged PR and QT interval or widening of QRS
hypokalemia and hyperkalemia levels
under 3.5 mEq/L
over 5.0 mEq/L
flaccid paralysis and ascending paralysis
hyperkalemia
hypokalemia
sodium bicarb, glucose, and insulin can do what
drive K++ cells intracellularly
hyporeflexia can be what
hyperreflexia
hyporeflexia: hypokalemia
hyperreflexia: hypernatremia
hypoaldosteronism can be what
hyperaldosteronism
hyperkalemia
hypomagnesium
hyperPTH
hypoPTH
Hyper: hypophosphatemia and hypercalcemia
hypo: hypocalcemia and hypomagnesium
calcium gluconate for what
severe hyperkalemia
hypermagnesium
rhabdomysis can appear in what
hypokalemia
hypophosphatemia
when to get a corrected calcium and an ionized calcium
corrected in hypercalcemia
and ionized in hypocalcemia
hypernatremia level if what
over 145 mEq/L
low urine Na and polyuria
DI
what to worry about in hypernatremia
brain cell shrinkage and DI
Na greater than 200
do dialysis
what is the most common electrolyte disorder seen in general hospital population secondary to use of hypotonic fluid administration
hyponatremia
hypovolemia and cheyne stokes respirations
hyponatremia
hypernatremia occurs in who
elderly and may occur in infants with diarrhea
neurologic manifestations of hypernatremia
thirst(from hypertonicity), restlessness, irritability, disorientation, lethargy, delirium, convulsions, coma
thirst(from hypertonicity), restlessness, irritability, disorientation, lethargy, delirium, convulsions, coma
neurologic manifestations of hypernatremia
non neurological symptoms of hypernatremia
dry mouth, dry mucous membranes, lack of tears, decreased salivation, flushed skin, tachycardia, hypoTN, fever, oliguria, anuria, hyperventilation, lethargy, HYPERREFLEXIA
6 hypernatremia causes pnemonic
Diuresis
dehydration
DI
docs(iatrogenic)
diarrhea
disease(kidney, sickle cell)
dry mouth, dry mucous membranes, lack of tears, decreased salivation, flushed skin, tachycardia, hypoTN, fever, oliguria, anuria, hyperventilation, lethargy, hyperreflexia
non neurological symptoms of hypernatremia
urine sodium decreased/elevated vs concentrated/diluted
decreased if hypernatremia is due to extrarenal losses and elevated if due to renal losses or sodium excess.
Concentrated with extrarenal losses and diluted with DI
antidiuretic stimulation and DI
it does not increase urine osmolality in nephrogenic DI
how to indicate a hyperosmolar coma
elevated serum glucose
decreased UO
increased urine osmomality
urine osmolality under 100
and 100-300
central DI
nephrogenic DI
hypernatremia treatment
* preferred route
*unstable vital signs
* hypovolemia present
*dialysis
*caution in what
free water orally is preferred, can also do IV or SQ 5% dextrose solution
unstable: do isotonic 0.9% NaCl
treat hypovolemia first(isotonic saline or LR) then the hypernatremia
dialysis if sodium greater than 200 mEg/L
caution because rapid correction can cause pulmonary or cerebral edema, especially in pts with DM
hyponatremia levels
sodium less than 130-135
hyponatremia usually due to what
increased ADH
hyponatremia with hypervolemia occurs when
in the setting of CHF, nephrotic syndrome, renal failure, hepatic cirrhosis
hyponatremia with euvolemia occurs when
with hypothyroidism, glucocorticoid excess, SIADH
SIADH
The syndrome of inappropriate antidiuretic hormone hypersecretion (SIADH) is characterized by excessive release of antidiuretic hormone (ADH or vasopressin) from the posterior pituitary gland or another source. The result is HYPOTONIC hyponatremia and sometimes fluid overload.
if you suspect SIADH…
CT to rule out CNS d/o and CXR to rule out lung pathology
demeclocycline for what?
risks?
- for chr hyponatremia unresponsive to fluid restriction; to induce nephrogenic DI.
- may cause neprotoxicity in pts with cirrhosis
ADH from what
pituitary hormone
tx for neurogenic(central) DI
what to do for mild disease
nephrogenic DM
diet
- parenteral or intranasal desmopressin
- diuretics, chlorpropamide, carbamazepine
- HCTZ, amiloride diuretics, indomethacin
- limited salt and protein
SIADH found in what diseases
It is usually found in patients diagnosed with small-cell carcinoma of the lung, pneumonia, brain tumors, head trauma, strokes, meningitis, and encephalitis.
SIADH
urine osmolality
urine sodium
osmolality greater than 100
sodium greater than 40
hyponatremia clinical symptoms
lethargy, disorientation, muscle cramps, anorexia, hiccups, N/V, seizures
signs of hyponatremia
HYPOreflexia, orthostatic hypoTN, cheyne stokes respirations, coma, stupor, delirium, agitation
lethargy, disorientation, muscle cramps, anorexia, hiccups, N/V, seizures
hyponatremia clinical symptoms
HYPOreflexia, orthostatic hypoTN, cheyne stokes respirations, coma, stupor, delirium, agitation
signs of hyponatremia
what can progress to seizures, coma, or brainstem herniation
hyponatremia
formula for serum osmolality
(2 x serum Na) + (BUN/2.8) + (glucose/18)
dangers of correcting hyponatremia too rapidly
central pontine myelinolysis or osmotic demyeination
order what tests if SIADH suspected
CT and CXR
hyponatremia treatment in
1) hypervolemic & euvolemic
2) hypovolemic
1) water restriction +/- diuretics
2) Normal saline
chronic hyponatremia tx
1) rate
2) unresponsive to fluid restriction
3) euvolemic or hypervolemic hyponatremia
1) over 72 hr duration with <8 mEq/L/day
2) demeclocycline
3) vasopressin antagonists(conivaptan)
causes of DI
1) neurogenic
2) nephrogenic
3) acquired
Neurogenic: deficient secretion of ADH from pituitary
nephrogenic: kidneys unresponsive to normal vasopressin levels, inherited X linked trait,
acquired from lithium therapy, HYPOkalemia, HYPERcalcemia, or renal disease
main symptoms of DI
polyuria(50-60 mL/kg/day), nocturia, polydipsia,
maybe seizures
how to differentiate neurogenic and nephrogenic DI
Water deprivation and desmopresin testing(DDAVP):
NEUROGENIC(central) DI: dec urine output and increased urine osmolality
if little or no change in urine osmolality, it is most likely NEPHROGENIC DI
urine osmolality less than 250 mOsm/kg
despite hyperkalemia
it is NEPHROgenic DI
tx for central DI and nephrogenic DI
central: DDAVP
nephrogenic: salt restriction and water intake, thiazide diuretics
labs in volume depletion
hemocrit and serum albumin increased
urinary sodium decreases
urea increases (secondary to urine stasis in nephron) but little change in serum Cr
