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Renal > 9 - Dyskalemias > Flashcards

9 - Dyskalemias Flashcards

1
Q

largest store of ICF potassium is in

A

muscle

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2
Q

clinical scenarios in which ICF potassium floods ECF

A

crush injuries
rhabdomyolysis
acute liver failure
hemolysis

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3
Q

3 short term causes of K uptake by cells

A

insulin
epi (beta 2)
alkalosis (less important)

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4
Q

beta blockers have what effect on serum K

A

higher after ingesting K load

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5
Q

urinary K is from filtered, secreted, or both?

A

secreted

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6
Q

2 factors regulating renal K secretion by principal cells

A

aldosterone

distal Na delivery

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7
Q

results of aldosterone action

A

lumen negativity in CCD

K and H secretion, Na reabsorption

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8
Q

hypokalemic periodic paralysis

A

intermittent acute attacks of muscle weakness w/ hypokalemia

triggered by large carb meals, rest post exercise

2 forms - AD mutation in DHP sensitive Ca channel OR thyrotoxicosis

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9
Q

3 possibilities for hypokalemia w/ metab alkalosis and high urine Cl

A

loop/thiazide diuretics
bartter’s syndrome
gitelman’s syndrome

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10
Q

Bartter’s syndrome

A

mutation in transporters in TAL of LoH
phenotype is that of pt taking loop diuretic > dec fn of Na/K/2Cl channel

hypokalemia, metab alkalosis, absence of HTN, hypocalcemia

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11
Q

Gitelman’s syndrome

A

mutation in Na/Cl cotransporter in DCT - looks like pt is on thiazide diuretics

hypokalemia, metab alkalosis, no HTN, hypercalcemia

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12
Q

example of condition that can cause hypokalemia with metab alkalosis and low urine Cl

A

vomiting:
lose H from stomach > absorb bicarb in small intestine
excess plasma bicarb > overwhelms reabs in PCT > lose as NaBicarb
volume depletion > stim aldosterone > K loss, > PCT Na and Cl reabs > low urine chloride

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13
Q

what is the next step in evaluating a pt w/ hypokalemia and high BP?

A

check renin and aldosterone levels

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14
Q

causes of hypokalemia w/ HTN and high renin and aldosterone

A

renin secreting tumor
RAS > hypoperfused kidney keeps secreting renin regardless of volume status

both cause K wasting from aldosterone and high BP from NaCl retention

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15
Q

causes of hypokalemia w/ HTN and low renin and high aldosterone

A

Conn’s syndrome - aldosterone secreting tumor
bilateral adrenal gland hyperplasia
glucocorticoid remediable aldosteronism (GRA)

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16
Q

glucocorticoid remediable aldosteronism (GRA)

A

AD inheritance
crossover of aldosterone synthase and steroid 11B-hydroxylase that causes aldosterone secretion to be under control of ACTH instead of ATII

tx w/ dexamethasone to suppress ACTH

17
Q

causes of hypokalemia w/ HTN and low or normal renin and aldosterone

A

Cushing’s syndrome
Syndrome of Apparent Mineralocorticoid Excess (SAME)
Liddle’s syndrome

18
Q

SAME

A

syndrome of apparent mineralocorticoid excess
dysfunctional enzyme 11B-OHSDH that normally breaks down cortisol. extra cortisol in principal cell binds to mineralocorticoid receptor and acts like there is too much aldosterone > hypokalemia and HTN

19
Q

licorice (glycyrrhizic acid) can cause what syndrome?

A

SAME

20
Q

Liddle’s syndrome

A

mutation in Na channel (eNaC) in CD principal cell > always open
causes hypokalemia, HTN, metabolic alkalosis (looks like hyperaldosteronism)
tx: block that channel (amiloride)

21
Q

clinical presentation of hypokalemia

A

asymptomatic until nephrogenic DI due to ADH resistance

22
Q

U wave is pathognomonic for

A

hypokalemia

23
Q

tx for hypokalemia

A

give K - oral is safest, IV burns small vessels

24
Q

K rich foods

A

potatoes, beans, avocados, spinach, banana, tomato, raisin, fish

25
Q

3 causes of impaired K entry into cells resulting in acute hyperkalemia

A 
lack of insulin - hyperglycemia pulls K rich water out of cells
SYNS blockade (beta blockers)
inorganic acidoses
26
Q

why do inorganic acidoses cause hyperkalemia but organic ones (lactic for ex) dont?

A

in organic, the anion can follow H in so K doesnt have to leave
in inorganic, the anion often can’t follow H in, so K is driven out

27
Q

2 main causes of chronic hyperkalemia

A

renal failure

hypoaldosteronism (includes K sparing diuretics which block aldosterone)

28
Q

2 times when you might be in a hypoaldosterone state

A

type 4 RTA

spironolactone

29
Q

hyperkalemia clinical presentation

A

depolarizes cardiac muscle - peaked T waves, loss of P wave, widened QRS, basically progressing towards sine wave / Vfib
skeletal muscle weakness

30
Q

hyperkalemia tx

A

stabilize cardiac fn w/ IV calcium (doesnt fix hyperkalemia at all)
shift K into cells (quick fix) - insulin+glucose, beta 2 agonist, NaBicarb (may not work in renal failure)
remove K from body - diuretics, cathartic or cation exchange resin (kayexalate), dialysis

31
Q

why does high aldosterone cause alkalosis?

A

intercalated cell secretes H allowing bicarb to enter blood

32
Q

how do you differentiate bartter’s from gitelman’s?

A

urine calcium

Renal (20 decks)

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