K+ Disorders (lec 3)

Question 1

K+ is major ion where?

Answer 1

intracellular

Question 2

Major route of K+ elimination?

Answer 2

renal excretion

Question 3

Regulation of K+ balance and excretion happens where?

Answer 3

distal nephron

Question 4

K+ level for Hyperkalemia?

Answer 4

serum K+ > 5.0

> 6 = critical

Question 5

Causes of HyperK+? (4)

Answer 5

1) pseudohyperK+ (false)
2) ↓ excretion
3) redistribution from ICF to ECF
4) excess administration

Question 6

HyperK+ presentation:

Neuro?

EKG?

Answer 6

Neuro: weak, numb, flaccid, hypoactive DTR

EKG:
Early = tall, peaked T-wave
Final = sine wave w/ arrest

Question 7

Most common cause of Pseudohyperkalemia?

Answer 7

hemolysis from poor venipuncture

broken RBCs release K+

Question 8

Inadequate excretion etiology? (3)

Answer 8

Renal failure: check BUN/creatinine

Meds: K+-sparing diuretics (spironolactone)

Hypoaldosteronism:
Adrenal insuff
ACE inhib
NSAIDs

Question 9

Redistribution of K+ from ICF to ECF caused by? (3)

Answer 9

tissue damage
acidosis
↓ insulin

Question 10

How does acidosis (↓ pH) effect serum K+ levels?

Answer 10

0. 1 ↓ in pH ->

0. 5 - 1.0 mEq/L ↑ in serum K+

Question 11

Excess administration of K+ typically caused by?

Answer 11

Rx K+ supplements too high

K+-containing salt substitutes

Question 12

HyperK+ tx?

Answer 12

1) r/o pseudo (repeat test)
2) correct levels
3) correct cause

Question 13

Rapid correction of HyperK+? (3)

Answer 13

By IV:

1) CaCl (protect heart),
2) NaHCO3 (↑ pH),
3) D50W + insulin (dextrose keeps insulin from dropping glu too much)

Question 14

Slow correction of HyperK+? (3)

Answer 14

Diuretics
Na+/K+ exchange resin (kayexalate + sorbitol)
Dialysis

Question 15

K+ level for Hypokalemia?

Answer 15

serum K+ < 3.5

< 3 is dangerous

Question 16

Causes of HypoK+? (4)

Answer 16

1) ↓ intake
2) GI loss
3) Renal loss
4) Redistribution from ECF to ICF

Question 17

HypoK+ presentation:

Neuro?

EKG?

Other?

Answer 17

Neuro: malaise, weak, cramps, paralysis

EKG: U-waves

Polyuria/dipsia

Question 18

Inadequate intake exacerbated by?

Answer 18

K+-losing meds (e.g. diuretics)

Question 19

GI loss of K+ (U) from?

Answer 19

V/D
Fistula
tumor

Question 20

Renal loss of K+ (U) from?

Answer 20

Diuretics
Osmotic diuresis (hyperglycemia, alcohol)

Question 21

Redistribution of K+ from ECF to ICF cause by?

Answer 21

alkalosis
↑ insulin
mineralocorticoid excess (steroids, cushings)

β-agonists: ↑ cellular K+ uptake and ↑ insulin secretion

Question 22

HypoK+ tx?

Answer 22

*Digitalis makes hypoK+ more critical

1) Check for hypoMg (low Mg makes low K+ harder to correct)
2) find cause

If unknown, order 24º urine potassium

Question 23

24º urine potassium results?

Answer 23

20 = renal loss

Question 24

Rapid correction of HypoK+?

Answer 24

IV: KCl
Cardiac monitor
Check STAT K+ every 2-4 hrs

Question 25

Slow correction of HypoK+?

Answer 25

oral K+

Question 26

What med makes hypoK+ more dangerous?

Answer 26

Digitalis