Potassium Balance

Question 1

5 physiologic factors that stimulate K+ secretion in distal tubule

Answer 1

1. aldosterone
2. high distal Na+ delivery
3. high urine flow rate
4. metabolic alkalosis
5. high [K+] in tubular cells

Question 2

factors influencing aldosterone release

Answer 2

RAAS and hyperkalemia

Question 3

3 ways uncontrolled diabetes mellitus leads to hypokalemia

Answer 3

1. osmotic diuresis
2. increased urine flow rate
3. increased distal Na+ delivery

Question 4

K+ handling in CKD

Answer 4

increased K+ secretion by aldosterone production, increased secretion by intestines and colon

Question 5

When may you see hyperkalemia in CKD?

Answer 5

1. no increase in aldosterone
2. type 4 RTA (diabetic nephropathy, chronic interstitial nephritis)
3. drugs inhibiting aldo production/secretion (ACE I, ARBs, NSAIDS, heparin)

Question 6

K+ shifts due to:
alkalosis
inorganic acidosis (normal anion gap)
organic acidosis (high anion gap)

Answer 6

in
out
no K+ efflux or influx

Question 7

how does insulin affect K+

Answer 7

stimulates Na+-K+ ATPase resulting in K+ influx

Question 8

why does epinephrine cause K+ influx

Answer 8

B2 adrenergic stimulation outweighs alpha adrenergic

Question 9

how is FE K different in hypokalemia from renal or extra-renal causes?

Answer 9

if renal, FE is high

if extra-renal, FE is low

Question 10

how is FE K different in hyperkalemia from renal or extra-renal causes?

Answer 10

if renal, FE is low

if extra-renal, FE is high

Question 11

how is TTKG different in hypokalemia from renal or extra-renal causes?

Answer 11

if renal, TTKG is high

if extrarenal, TTKG is low

Question 12

how is TTKG different in hyperkalemia from renal or extra-renal causes?

Answer 12

if renal, TTKG is low

if extrarenal, TTKG is high

Question 13

in the kidney TTKG is an indirect measurement of what?

Answer 13

aldosterone activity

Question 14

why do patients with diabetic ketoacidosis present with hyperkalemia?

Answer 14

decreased insulin along with hyperosmolality leads to K+ release from cells

Question 15

unique EKG change with hypokalemia

Answer 15

U wave

Question 16

EKG changes with hyperkalemia

Answer 16

peaked T waves
depressed ST segment
prolonged PR interval

Question 17

psuedohyperkalemia in leukocytosis and thrombocytosis

Answer 17

leukocytosis - elevated plasma and serum K+

thrombocytosis - elevated serum K+

Question 18

when do you use calcium chloride or calcium gluconate?

Answer 18

hyperkalemia with EKG changes

Question 19

what is usually added to treatment of hyperkalemic patients when giving insulin and B2 adrenergic agonists?

Answer 19

glucose (D50)

Question 20

when do you treat with NaHCO3

Answer 20

if hyperkalemic patient is acidotic but has functioning kidneys