fluids & electrolytes

Question 1

what affects ECF vs ICF

Answer 1

ECF: changes in sodium CONTENT
ICF: changes in serum sodium concentration

Question 2

ECF is assessed via P.E. list some signs of low ECF

Answer 2

• Sx: thirst, lightheadedness, palpitations
• signs: orthostasis, urine output, dry mouth/moist membranes, dry axilla, low/high JVP, skin turgor or edema

Question 3

2 physiologic stimuli for ADH release

Answer 3

high osmolality & low volume

Question 4

what stimulates water absorption w/o sodium

Answer 4

ADH

Question 5

hyponatremia means there is water loss from which compartment?

Answer 5

ICF.. it moved into the ECF

Question 6

what 2 things cause hyponatremia w/ high osmolality

normal osm: 275 to 290 mOsm/kg

Answer 6

hyperglycemia
mannitol infusion

Question 7

hyponatremia + normal ECF (net water gain, no change in salt) is caused by what 4 conditions?

Answer 7

• SIADH
• primary polydipsia
• hypothyroidism
• adrenal insufficiency

Question 8

hyponatremia + high ECF (++ water, + salt) is caused by what 4 conditions?

THEY HAVE EDEMA

Answer 8

renal failure
heart failure
liver failure
nephrotic syndrome

Question 9

hyponatremia + low ECF (- water, – salt) is caused by what 4 conditions?

Answer 9

• extra renal: vomiting, diarrhea
• renal: diuretics, osmotic diuresis

Question 10

what are 5 symptoms of hyponatremia

Answer 10

• HA
• nausea
• confusion
• falls
• seizures

excess water in cells including brain cells

Question 11

treatment of extreme hyponatremia

Answer 11

3% hypertonic saline

Question 12

why do you make more urine with DI?

Answer 12

thirst center works fine. so you drink water which decreases osmolality and makes ADH stop being secreted causing you to NOT hold onto water = more urine.

Question 13

2 causes of central DI and 3 causes of nephrogenic DI

Answer 13

• Central: neurosurgery, trauma
• nephrogenic: lithium, hypokalemia, hypercalcemia

Question 14

you do the water deprivation test & the urine osmolality is unchanged what is this?

Answer 14

• DI
• if they respond to DDAVP then its central DI

Question 15

when doing the water deprivation test, what result cues you to check for DDAVP response?

Answer 15

if urine osm. does not change

Question 16

you do the water dep. test and urine osmo increases, what does this mean?

Answer 16

psychogenic polydipsia

Question 17

what causes hypernatremia + normal ECF (pure water loss)

Answer 17

DI

Question 18

3 things that cause hypernatremia + low ECF (— water loss, - salt loss)

Answer 18

GI (diarrhea)
skin (burns, sweat)
renal (diuretics)

Question 19

2 things that cause hypernatremia + high ECF (+ water gain, +++ salt gain)

Answer 19

hypertonic fluid administration
mineralocorticoid excess

Question 20

treatment of volume contraction (sodium loss)

Answer 20

give it back– LR or 0.9% normal saline

Question 21

how does hypokalemia affect cardiac cell function?

Answer 21

hyperpolarizes the cell membrane causing delayed ventricular repolarization, ventricular instability, arrhythmias

Question 22

how does hyperkalemia affect cardiac cell function? (5)

Answer 22

• sustained subthreshold depol.
• delayed depolar.
• EKG changes
• arrhythmias
• death

Question 23

where is most of k+ reabsorbed?

Answer 23

• proximal convoluted tubule

Question 24

3 general causes of hypokalemia

Answer 24

• decreased dietary intake
• increased urine losses– diuretics
• increased stool losses– diarrhea illnesses, laxative use

Question 25

what level do you start replacing K+

Answer 25

3.5

Question 26

4 general causes of hyperkalemia

Answer 26

• transcellular shift: tissue breakdown, acidosis, use of BB, insulin deficiency
• increased intake
• decreased renal function– AKI, CKD, ESRD
• hypoaldosteronism

Question 27

4 steps to treating hyperkalemia

Answer 27

1. restore excitaility– calcium fluconate or CaCl
2. Insulin + glucose (if acidosis, add sodium bicard), B2 agonist
3. Kayexalate (sodium polystyrene sulfonate
4. enhance urine output– IVF, diuretics, dialysis

C BIG K DIE