Electrolyte Disorders

Question 1

what serum sodium concentration is defined as hyponatremia?

Answer 1

135 mEq/L

Question 2

what is the most common cause of hyponatremia in hospitalized patients?

Answer 2

hypotonic fluids

Question 3

what can happen with mismanagement of hyponatremia?

Answer 3

cerebral osmotic deficiency

Question 4

three parts of careful history examination for electrolyte disorders?

Answer 4

new medications
changes in fluid intake
fluid output

Question 5

how may modest hyponatremia actually be severely symptomatic?

Answer 5

if it is developed acutely, over hours to days.

Question 6

what are some severe symptoms of hyponatremia?

Answer 6

respiratory arrest
seizure
coma
brain damage
brainstem herniation
death

Question 7

what is the initial step in hyponatremia treatment?

Answer 7

restriction of free water intake and hypotonic solution

Question 8

generally, free water intake should be less than how much when doing treatment for hyponatremia?

Answer 8

1-1.5L a day

Question 9

what type of saline may be necessary for patients with negative free water clearance?

Answer 9

hypertonic solution

Question 10

what causes most of the serious complications of hyponatremia, like iatrogenic cerebral osmotic demyelination?

Answer 10

from over rapid sodium corrections. generally catastrophic and irreversible

Question 11

what is sodium concentration is defined as hypernatremia?

Answer 11

sodium concentration greater than 145 mEq/L

Question 12

what condition can usually accompany hypernatremia?

Answer 12

hypovolemia due to free water loss

Question 13

what are the defenses against hypernatremia?

Answer 13

intact thirst mechanism and access to water are the primary defense

Question 14

signs and sx of hypernatremia from dehydrated patient to severe

Answer 14

hypotension (orthostatic)
oliguria
>
lethargy, irritability, weakness
>
SEVERE: (sodium over 158 mEq/L)
hyperthermia
delirium
seizures
coma

Question 15

fluids should be administered for hypernatremia over how long of a time period?

Answer 15

48 hr time period

Question 16

what is the appropriate serum sodium concentration rate for hypernatremia?

Answer 16

1 mEq/L/h

Question 17

what happens with severe rapid correction of hypernatremia?

Answer 17

cerebral edema and neurological impairment

Question 18

what serum concentration of potassium is considered hypokalemia?

Answer 18

levels less than 3.5 mEq/L

Question 19

severe hypokalemia may induce what conditions?

Answer 19

arrhythmias and rhabdomyolysis

Question 20

what are some of the causes of hypokalemia?

Answer 20

insufficient dietary intake

intracellular shift from the extracellular space (insulin and beta agonists, alpha agonist stimulation)

the most common cause is GI loss from diarrhea.

Question 21

why is GI loss the most common site of potassium loss?

Answer 21

potassium concentration in intestinal secretion is ten times higher than in gastric secretions, so more is lost with diarrhea.

Question 22

Signs and SX of hypokalemia

Answer 22

Moderate: weakness, fatigue, cramps
Severe: flaccid paralysis, hyporeflexia, tetany, rhabdomyolysis

Question 23

what might be shown on ECG with hypokalemia?

Answer 23

decreased amplitude and broadening of T waves, premature Ventricular contractions, Depressed ST segments

Question 24

what is the fastest and easiest treatment for hypokalemia?

Answer 24

oral potassium supplementation (40-100mEq/day over a period of days to weeks)

Question 25

who should patients with unexplained hypokalemia/refractory hypokalemia be referred to?

Answer 25

endocrinology or nephrology

Question 26

what is the serum concentration of a patient with hyperkalemia?

Answer 26

greater than 5.0 mEq/L

Question 27

hyperkalemia may develop in patients taking what kind of medications?

Answer 27

ACE inhibitors
Angiotensin receptor blockers
potassium sparing diuretics

(meds that interfere with renal functions)

Question 28

acidosis makes intracellular potassium shift which way?

Answer 28

extracellularly (exchange with H+)

Question 29

Signs and SX of hyperkalemia

Answer 29

muscle weakness
flaccid paralysis
ileus

Question 30

what may cause raised potassium levels by 1-2 mEq/L on blood samples?

Answer 30

fist clenching during venipuncture.

Question 31

ECG changes in hyperkalemia

Answer 31

bradycardia
PR interval prolongation
peaked T waves
QRS widening
bundle branch or atrioventricular block

Question 32

what are the terminal events on ECG of hyperkalemia?

Answer 32

V fib and cardiac arrest

Question 33

Treatment for hyperkalemia

Answer 33

insulin, bicarbonate, and beta agonists
IV calcium
Hemodialysis may be required to remove potassium in patients with acute or chronic kidney injury.
Loop diuretics (furosemide, bumetanide)

Question 34

severe hyperkalemia should be sent to ER. What are the signs of severe hyperkalemia?

Answer 34

greater than 6 mEq/L
any hyperkalemia associated with ECG changes
concomitant illness (rhabdo, metabolic acidosis)