Tuesday Na and K

Question 1

normal body stores of K

how much can the kidney get rid of in a day at max?

Answer 1

3000 to 4000 meq

(50 - 55 meq per kg)

98% is intracellular

kidney can get rid of like 400 meq/day max

Question 2

if you are seeing a dialysis patient with weak legs what do you think

Answer 2

kigh K

Question 3

EKG changes of hypokalemia

Answer 3

DISCLAIMER: THIS WAS MY WAY OF REMEMBERING IT, IT MAY NOT BE 100% ACCURATE FOR PR INTERVAL PROLONGATION

PR interval prolongation (hypokalemia -> bigger gradient of K on the inside of the cell compared to the outside (it’s like as if your Na/K pump is working TOO well) -> increased membrane potential -> takes longer to depolarize -> signal takes longer to travel from atria to ventricles)

ST depression (as a result of increased membrane potential)

Flattened or inverted T wave

U - wave (due to repolarization of the septum as a different time that the ventricular wall. slower depolarization may cause this) (U OK? -> U waves with hypOKalemia)

QRS widening (similar reason as PR elongation)

Question 4

EKG changes of hyperkalemia

Answer 4

PR prolongation

elevated T waves

widened QRS

Question 5

when are you fucked

Answer 5

when you are hyperkalemic and then get a metabolic acidosis

because the way you get rid of H+ is by antiporting it with K+

Question 6

loop diuretics do what to potassium

Answer 6

block NKCC, cause you to excrete more

get hypokalemia

Question 7

where is aldosterone made in the body

Answer 7

adrenal cortex

Question 8

chronic hypokalemia does what to the kidneys

Answer 8

interstitial fibrosis

Question 9

increasing catecholamines/beta agonists will do what to your potassium

Answer 9

cause hypokalemia

Question 10

metabolic alkylosis due to vomiting can do what to your potassium levels

Answer 10

can cause COMPENSATORY hypokalemia

compensatory holding onto H+, the K+/H+ antiporter wastes all your K

Question 11

if you have more “distal flow” in the kidney, what is going to happen to your potassium?

Answer 11

hypokalemia

more distal flow means you absorbed less in the proximal tubule, where you absorb with NKCC pumps

(loop diuretics would cause increased distal flow and hypokalemia)

Question 12

Eating what would cause hypokalemia in someone who is on a loop diuretic

Answer 12

eating more salt.

you would get even more distal flow and then the Na would be sucked up in the distal region and the potassium would be excreted even MORE

Question 13

having low magnesium does what to your K and how

Answer 13

it causes hypokalemia

magnesium normally inhibits ROMK channels.

no Mg and you potassium spills out (can be aggrivated by intake of sodium)

Question 14

metabolic acidosis due to diarrhea/laxative can do what to your potassium levels

Answer 14

causes PRIMARY hypokalemia

K+ follows HCO3- out of the GI tract when you poop

Question 15

which can cause rhabdo - hyper or hypokalemia

Answer 15

hypo

Question 16

insulin will take up potassium into the cells. what else does this?

Answer 16

catacholamines (that work on beta- adrenergic receptors)

Question 17

Three main causes of increase in serum K if total body K is normal

Answer 17

muscle or tissue breakdown
insulin deficiency with hyperglycemia
metabolic acidosis

Question 18

common drug that can cause high potassium

Answer 18

ace inhibitors (lack of aldosterone causes the Na/K antiporter to stop)

Question 19

what do NSAIDs do to you aldosterone levels?

Answer 19

NSAIDS block prostaglandin

prostaglandins cause the juxtaglomerular cells lining the afferent arterioles to release renin, activating the renin–angiotensin–aldosterone system, to increase blood pressure.

no prostaglandins means no aldosterone

Question 20

addisons

Answer 20

adrenals can’t make mineralcorticoids

get lack of aldosterone and cortisol (which is actually a glucocorticoid)

Question 21

what do you think if someone’s potassium is 6.5-7 with no EKG changes

Answer 21

their sample may have been hemolysed, a lab error causing increased serum K in the plasma that isn’t actually in vivo

Question 22

having hyponatremia will do what if you have hyperkalemia

Answer 22

it will make it worse because you won’t be secreting K with the Na/K antiporter

Question 23

Tx for hyperkalemia and why

Answer 23

FIRST: antagonize
Calcium IV: antagonizes the effects of hyperkalemia on muscle cells in minutes

THEN: move into cells
glucose and insulin: shifts K into the cells

Bicarb: making them alkalemic shifts K into the cells via the K+/H+ antiporter

LATER…excrete
Loop diuretic
kayexalate
dialysis

Question 24

spironolactone does what to your potassium

Answer 24

hyperkalemia

spironolactone is an aldosterone receptor antagonist (THIS IS NOT THE SAME AS AN ARB. ARBS ARE ANGIOTENSIN RECEPTOR BLOCKERS like losartan)

so it blocks the Na/K antiporter

Question 25

values for hyper and hypo natremia

Answer 25

less than 135 or more than 145

Question 26

where is ADH made

Answer 26

produced in the hypothalmus supraoptic and paraventricular nuclei get stored in secretary granules that move down to the posterior lobe of the pituitary

Question 27

Describe what is meant by non osmotic stimuli of ADH

Answer 27

Non osmotic sources of stimulation for ADH secretion Come from baroreceptors for hypovolemia can cause retention of water even if you have a low osmolality used to keep the brain perfused and BP up in hypovolemia

Question 28

what does ADH bind to

Answer 28

V2 receptor makes aquaporin 2 move into the luminal membrane

Question 29

does the kidney think the body is volume (overloaded or depleted) when on a diuretic

Answer 29

kidney can think that the body is volume depleted because you are getting rid of sodium on a diuretic

Question 30

urine osmolality of sodium can range from _____ -______

Answer 30

can dilute to 50 - can concentrate to about 1400 use 50-1000 for her calculations though for the test i guess........

Question 31

when do you declare someone oliguric

Answer 31

when someome is making less that 500-600 cc of urine a day

Question 32

pseudohyponatremia

Answer 32

when you have a low sodium but your plasma osmolality is normal states of high protein (like multiple myeloma) or high lipids (like high triglycerides) or high sugar ( like mannitol to treat cerebral swelling)

Question 33

high urine sodium means the kidneys are behaving as if the body is fluid _____ (expanded or depleted)

Answer 33

expanded

Question 34

how much water do you have to drink in order to overcome the renal capacity to excrete water

Answer 34

10-15 liters

Question 35

what are you thinking if someone is hyponatremic, urine osmolarity >100, UNa+ is less than 10

Answer 35

their body is trying to retain sodium so that they retain water. This is normal for hypovolemia can be because of GI loss, burns, diuretics (late), cortisol deficiency

Question 36

what are you thinking if someone is hyponatremic, urine osmolarity >100, UNa+ is less than 10 but they are volume expanded

Answer 36

they probably have edema, but the kidney thinks that they are volume depleted due to hyponatremia, so the kidney is trying to retain sodium inappropriately (because it is not perfused) may be due to CHF/cirrhosis/nephrosis

Question 37

what are you thinking if someone is hyponatremic, urine osmolarity >100, UNa+ >10, and volume depleted

Answer 37

this is a salt wasting nephropathy. rarer, can be seen with diuretics (early), adrenal insufficiency, hypothyroidism

Question 38

what are you thinking if someone is hyponatremic, urine osmolarity less than 100

Answer 38

probably primary polydypsia, beer potomania, or tea and toast syndrome they are getting rid of excess water to correct hyponatremia THEY ARE NOT VOLUME DEPLETED SO THEY DON'T CONCENTRATE THEIR URINE

Question 39

what are you thinking if someone is hyponatremic, urine osmolarity >100, UNa+ >10, and volume appropriate or expanded

Answer 39

syndrome of inappropriate ADH secretion (SIADH) classically from lung cancer, also

Question 40

how do you treat someone who is hyponatremic and volume expanded

Answer 40

restrict free water intake or treat state of poor perfusion (diuretics)

Question 41

when would you give an ADH antagonist and what are they called

Answer 41

the "vaptans" target V2 receptors hyponatremia with volume expansion use them in an effort to get free water off

Question 42

what is the maximum rate of correction of hyponatremia

Answer 42

.5 meq/liter/hour

Question 43

what common-ish drug is known to cause nephrogenic diabetes insipidus?

Answer 43

lithium need to give them just water, not saline