Fluids, Electrolytes, and Imbalances - Exam 2 Flashcards
Na is the major what?
major cation in extracellular fluid (ECF)
what does Na regulate?
regulates transmission of impulses in nerve and muscle fibers
Na is the main factor in determining what?
main factor in determining volume of extracellular space
who is a risk with hyponatremia?
elderly
what does Na help maintain?
helps maintain acid-base balance
what is dysnatremias?
disruptions of Na concentration
has more to do with hydration (fluid status) than circulating sodium
what is the most common type of hyponatremia?
hypo-osmolality with hypervolemia
hyponaturemia and impaired water excretion?
pt is fluid overloaded, so Na is diluted -> have impaired water excretion
causes of impaired water excretion and hyponatremia
HF, cirrhosis, renal failure, aggressive IV fluid admin (give too much fluid)
how does hyperglycemia cause hyponatremia
high serum sugar causes the cells to release water diluting sodium while not overloading the body with water
how does hypertonic mannitol admin cause hyponatremia?
water movement out of brain cells
-given for cerebral edema to try to decrease ICP -> try to move water out of brain cells, but also moves water out of other cellist the body, so can dilute Na in the entire body
how does SIADH occur? what does SIADH cause?
- hyponatremia as a result of excess water
- result of increase in circulating ADH
- caused by hypersecretion or ectopic source (secreting too much ADH)
chronic alcoholics and hyponatremia
beer potomania syndrome - binge drinkers
-get chronic suppression of ADH with alcoholics
hyponatremia caused by water into occurs in who?
marathon athletes (need to check their Na first b/c don’t want to dilute them too much), drugs (ecstasy)
what is acute hyponatremia? chronic hyponatremia?
acute: < 48 hrs
chronic: >48 hrs or duration, unclear how long they’ve had it
the more acute the hyponatremia, the great there what?
the greater the complications
what are the most important determinants of onset of symptoms for hyponatremia?
the degree of hyponatremia and rapidity that it develops
-the more acute it is, the more severe it is
what are the first presentations of hyponatremia and at what levels of Na do you get them?
nausea and malaise
-Na falls below 125-130
hyponatremia sx’s at levels below 115-120
HA, lethargy, obtunded, seizures, coma, resp arrest, pulmonary edema
goals of tx for hyponatremia
- prevent further decline in serum Na concentration (#1)
- decr ICPin pts at risk for developing brain herniation
- relieve sx of hyponatremia
- avoid excessive overcorrection in pts at risk for osmotic demyelination syndrome
what is the first thing to do when treating hyponatremia?
prevent further decline in serum sodium concentation
what people are at risk for developing brain herniation from hyponatremia/are at risk of hyponatremia?
- competitive exercise, ecstasy, psychosis
- women and children post-op
- recent brain injury, surgery, neoplasm
what happens if you overcorrect Na too quickly?
get neurologic sx’s -> osmotic demyelination syndrome
how do you treat hyponatremia?
bolus 3% saline
what is the most common cause of hypernatremia? causes?
volume depletion/hypovolemia (fluid volume is low, so salt goes high)
-fever, sweating, vomiting, diarrhea, primary hypodipsia (ex: condition where you don’t drink)
what diabetes causes hypernatremia?
diabetes insipidus
how does diabetes insidious cause hypernatremia?
-passage of large volume of dilute urine
cause hypovolemic hypernatremia thru 2 mechanisms
2 mechanisms that diabetes insipidus causes hypernatremia?
- decreased secretion of ADH from posterior pituitary
2. increased renal resistance to ADH - can’t concentrate urine (passing lots of dilute urine)
most common cause of diabetes insipidus causing hypernatremia?
damage after trauma or surgery to the region of the pituitary and hypothalamus
primary hyperaldosteronism causing hypernatremia
- problem with the adrenal (usually a benign tumor)
- have excess production of aldosterone -> increased Na and water and decreased K
increased what and decreased what in primary hyperaldosteronism?
increased sodium and water and decreased K
altered thirst mechanism causing hypernatremia - common in who?
psych pts and elderly institutionalized pts
signs and sx’s of hypernatremia
AMS, ataxia, seizures, hyperreflexia, spasticity/twitching, irritability, lethargy
management of hypernatremia?
D5W IV
caution in what when treating hypernatremia?
hyperglycemia
treatment of diabetes insipidus?
desmopressen - ADH analog
K+ is the most abundant what?
cation
what is K+ vital to?
cell metabolism and neurologic and cardiac electrical transmission
what are the main regulators of K+?
kidneys
98% of K+ is ___?
intracellular, chiefly in muscle
K+ is secreted and reabsorbed where?
within the nephrons of the kidneys
most common causes of hypokalemia?
diuretic therapy, diarrhea, vomiting
what meds cause large shifts of K+ from extracellular to intracellular?
diuretics (esp Loops and Thiazides)
insulin
beta-adrenergic agonists (albuterol, terbutaline)
hypo___ can cause hypoK?
hypomagnesemia (b/c K and Mg are very intimately related)
hyperaldosteronism does what to K?
increases K excretion from kidneys
sx’s of hypokalemia?
muscle weakness/cramping
respiratory muscle weakness
palpitations
ileus, constipation, fatigue
get mostly what type of sx’s when hypokalemic?
muscle sx’s b/c most K is stored in the muscles (and also in muscles of the gut)
what is seen on an EKG if pt is hypokalemic?
flat T waves, ST segment depression, U waves
what can mild hypokalemia be treated with?
oral KCl
what does severe and symptomatic hypokalemia need to be treated with?
IV replacement w/K and continuous telemetry
if hypokalemic and also hypomagnesemia, what do you replete first?
must replete Mg first before K + replacement (b/c both are related)
Mg+ plays a big role in regulation of what?
the Na+K+ATPase pump
if see K+ above 7 or 8, what do you want to do?
redraw
-sometimes when draw blood cells, they smack against tube and break open and release K (hemolysis), so K will be falsely elevated -> redraw to confirm actually hyperkalemia
hyperkalemia can be due to what?
impaired urinary K+ excretion
common complication in renal disease/insufficiency
medications (ACEIs, ARBs, Aldosterone antagonists - spironolactone)
hyperkalemia is a common complication in what?
renal disease/insufficiency
meds that cause hyperkalemia?
ACEIs - Lisinopril
ARBs - Losartan
Aldosterone antagonist - spironolactone
what are the sx’s of hyperkalemia?
muscle weakness/paralysis, paresthesias, arrhythmias
what is seen on an EKG when hyperkalemic?
tall or peaked T waves, widened/bizarre QRS, flat P wave
TWiFP
what is the first thing given when treating hyperkalemia? why?
IV calcium-gluconate or chloride
-CARDIOPROTECTIVE - DOESN’T DECREASE K+
what meds actually treat hyperkalemia?
IV hypertonic glucose with regular insulin (moves excess K+ into the cells)
IV loop or thiazide diuretics (rapid removal of K+ from body)
treat what causes for hyperkalemia?
treat reversible causes - hypovolemia
PO treatment of hyperkalemia?
have to give resins that bind K+ and excreted in stool
-Kayexalate-sodium polysterene (not used much)
what else, besides meds, treats hyperkalemia?
hemodialysis
where is Ca primary stored?
bones and teeth
what processes require Ca+?
- blood coagulation
- nerve excitability
- development of action potentials for muscle contraction (skeletal, cardiac, smooth)
what factors influence serum Ca+ concentration?
PTH, vitamin D, calcium ion, phosphate
what is crucial for osteoclastic activity in bone? and ability of the intestines to store Ca?
Ca, phosphorous, and Vitamin d
what is the most common form of Ca found in the body and that is also usually measured?
ionized Calcium
most common causes of hypocalcemia?
- parathyroid disease
- thyroid disease
- thyroid or parathyroid-ectomy
- CKD
- vitamin d deficiency
Ca+ is bound to what in the serum? means what?
albumin
-means need to check Ca and also albumin
what is albumin and what is it produced what?
it’s a protein produced by the liver
what is the function of albumin/
the distribution of body fluids
carrier protein in the blood for steroids, fatty acids, and thyroid hormone
hypoalbuminemia can cause?
pseudohypocalcemia
to determine true Ca levels, what is required?
correction for albumin
sx’s of hypocalcemia?
- parasthesias
- hyperreflexia
- TETANY
- MUSCLE SPASM
- muscle cramps
- seizures
classic physical findings of hypocalcemia?
Chvostek sign - facial spasm following the percussion of the facial nerve
Trousseau’s sign - spasm of the hand elicited by inflation of a BP cuff
what does an EKG look like when hypocalcemia?
prolonged QT interval
treatment of severe symptomatic hypocalcemia?
IV supplements - calcium gluconate
if have low Mg and also low Ca, what must you correct first?
must correct a Mg deficit first
tx for asymptomatic or mild hypocalcemia?
- PO Ca+ replacement with asymptomatic hypocalcemia
- PO calcium carbonate, calcium citrate, calcium carbonate
what are the most common causes of hypercalcemia?
hyperparathyroidism and bone malignancy (multiple myeloma)
signs and sx’s of hypercalcemia?
MOANS, GROANS, STONES, AND PSYCHIATRIC UNDERTONES
-bone pain, muscle weakness, confusion, lethargy, constipation, nephrolithiasis
common sx’s seen in multiple myeloma and bone mets from cancers?
MOANS, GROANS, STONES, AND PSYCHIATRIC UNDERTONES
hypercalcemia tx
- volume expansion with isotonic saline
- salmon calcitonin with a bisphosphenate
- zoledronic acid (bisphosphenate)
how does calcitonin work to decrease Ca levels?
it decreases bone reabsorption and increases renal excretion of Ca
Mg+ is responsible for what?
- ATP processing
- macronutrient and energy metabolism
- neuromuscular transmission
- can block Ca+ and K+ channels
what is the principle reservoir of Mg+?
bone
Mg+ levels regulated by what?
intestinal absorption and renal excretion
if these are off, then Mg+ is off
hypomagnesemia is commonly seen in what?
chronic ETOH abuse (from poor dietary intake)
causes of hypomagnesemia?
-***chronic ETOH abuse
- reduced intestinal absorption
- increased renal excretion
- excessive GI loss (vomiting, diarrhea)
- starvation
- refeeding syndromes (after starvation and after gastric bypass)
what are the signs and sx’s of hypomagnesemia?
- lethargy, confusion, tremors, convulsion
- hyperreflexia, parathesias
- cardiac arrhythmias
what does an EKG look like with hypomagnesemia?
widening of QRS, conduction prolongation and ST segment depression
what is tx for mild asymptomatic hypomagnesemia?
oral replacement with Mg salts
- Mag-Ox (magnesium oxide)
- Slow-Mag (magnesium chloride)
- Mag-Tab (magnesium lactate)
precaution with what when treating hypomagnesemia with oral Mg salts?
may develop osmotic diarrhea
what is tx for severe or symptomatic deficiency of hypomagnesemia?
IV replacement
Mg sulfate
- careful monitoring for rebound hypermagnesemia and arrhythmias
- caution when giving Mg+ to renal pts
caution when giving Mg+ to what pts?
renal pts
careful monitoring for what when treating severe or symptomatic deficiency of hypomagnesemia?
careful monitoring for rebound hypermagnesemia and arrhythmias
hypermagnesemia seen in?
seen in:
- renal failure pts
- supratherapeutic replacement
- antacid abuse (milk of magnesium)
sx’s of hypermagnesemia?
- decreased deep tendon reflexes
- bradycardia
- hypotension
- flaccid paralysis
- cardiac arrest
- N, HA
- hypocalcemia
what does an EKG look like with hypermagnesemia?
- tall T’s
- widened QRS
- irregular conduction
- escape beats
tx of hypermagnesemia?
- dietary restriction
- elimination of magnesium containing meds
- saline + loop diuretics (too pee it out and dilute it)
-hemodialysis
