hyperkalemia Flashcards
definition of hyperkalemia
potassium greater than 5.5
EKG changes
peaked t-waves. think tent filled with K.
Excretion is decreased by the following:
absence of aldosterone, low sodium delivery to the distal tubule, low urine flow, low serum potassium level, renal failure.
function of k in the body
muscle contraction, regulation of the heart contractility, important for the kidney to function normally.
pseudohyperkalemia
term applied to the clinical situation in which in vitro lysis of cellular contents leads to the measurement of a high serum potassium level not reflective of the true in vivo level. condition occurs most commonly with red cell hemolysis during the blood draw
excessive intake
uncommon cause of hyperkalemia. the mechanisms for shifting postassium intracellularly and from renal excretion allow a person with normal postassium hemostatic mechansims to ingest virtually unlimited quantities of k in healthy individuals. most often its caused in a pt with impaired mechanisms for the intracellular shift of k or for renal k excretion.
decreased excretion
most common cause. causes of decreased renal k excretion include: renal failure, DM, sickle cell disease, medications
shift from intra to extracellular space
uncommon alone but can exacerbate hyperkalemia produced by a high intake or impaired renal excretion of potassium. it can be the major cause of hyperkalemia in: hyperosmol, rhabdo, tumor lysis, succinylcholine admin, insulin deficiency
symptoms of hyperkalemia
weakness and fatigue, frank muscle paralysis, shortness of breath, palpitations.
physical findings of hyperkalemia
vital signs generally are normal, could have bradycardia due to heart block or tachypnea due to respiratory muscle weakness.
lab tests for hyperkalemia
assess renal function. check serum BUN and creatinine levels to determine whether renal insufficiency is present. check 24 hour urine for creatinine clearance. estimate the GFR.
treatment
determine life threatening toxicity by performing ekg. if present: administer iv calcium gluconate to ameliorate cardiac toxicity. insulin and glucose. inhaler beta agonist. bicarbonate. kayexalate doesn’t do it fast but good for chronic control. dialysis is fastest and best
hypokalemia
think iatrogenic-thiazides/loop diuretics
3 mechanisms for hypokalemia
deficient intake
increased secretion
GI losses like vomiting or diarrhea-shift from extracellular to intracellular space.
symptoms of hypokalemia
nonspecific and predominantly are related to muscular or cardiac function. weakness and fatigue are the most common complaints. the muscular weakness that occurs with hypokalemia can manifest in protean ways, ie, dyspnea, constipation or abdominal distention, or exercise intolerance. rarely, muscle weakness progresses to frank paralysis. muscle cramps and pain can occur with rhabdomyolysis
