Regulation of K+ balance (Showkat)

Question 1

Storage of K in humans

Answer 1

98% intracellular

2% extracellular (90-95 mEq/d renal excretion, 5-10 mEq/d GI excretion)

Question 2

Stores & intake of K

Answer 2

120-140 mEq/dl ICF
4-5 mEq/dl ECF
100 mEq/d intake

Question 3

Places K+ is excreted

how? channel/transporter, energy, and signal

Answer 3

CCT & OMCD

ROMK channel on lumen side (counters Na+)
3Na+/2K+ ATPase on basolateral side
Aldosterone binding R-Aldo

also influenced by concentration/chemical gradients & permiability

Question 4

Places K+ is resorbed

how? channel/transporter, energy, and signal

Answer 4

TALH:
Na+/K+/2Cl- cotransporter (lumen)
K+ channel (lumen)
Na+/K+ ATPase (basolateral)
(counterbalanced by Cl- basolateral channel)

Question 5

Potassium excretion potentiated by

Answer 5

aldosterone

Question 6

K+ absorption determined by

Answer 6

flow rate

Question 7

4 causes of decreased renal K+ secretion

Answer 7

renal failure
distal tubular dysfunction
decreased distal tubular flow
hypoaldosterism

Question 8

3 effectors of internal potassium balance

Answer 8

Plasma conc of K+
Insulin
Epinephrine

Question 9

Relation to pH shift (increase/decrease in H+)

Answer 9

reciprocal shift of K+ balancing charge

Question 10

Metabolic acid-base disturbance or respiratory disturbance causes greater effect on K+?

Answer 10

Metabolic

Question 11

Bigger effect: organic acids or inorganic acids?

Answer 11

inorganic acids

Question 12

Cell proliferation effect on K+

Answer 12

consumes extracellular K+

Question 13

Cell lysis effect on ECF K+

Answer 13

increases/releases

Question 14

3 causes of Hyperkalemia

Answer 14

excessive intake
decreased renal excretion
internal redistribution

Question 15

Decreased renal excretion of K+ 4 reasons

Answer 15

acute/chronic renal failure
decreased distal tubular flow
distal tubular dysfunction
hypoaldosteronism

Question 16

Internal redistribution mechanisms for hyperkalemia (5)

Answer 16

insulin deficiency
beta2-adrenergic blockade
hypertonicity
acidemia
cell lysis

Question 17

EKG manifestations of K+:

4. 0 mEq/L
5. 0 mEq/L
6. 0 mEq/L
7. 0 mEq/L
8. 0 mEq/L

Answer 17

4. 0 mEq/L normal
5. 0 mEq/L peaked T-wave
6. 0 mEq/L Wide QRS complex, shortened QT interval, Prolonged PR Interval
7. 0 mEq/L Further widening of QRS complex, absent P-wave
8. 0 mEq/L Sinde-wave morphology, ventricular tachycardia

Question 18

signs of hyperkalemia

Answer 18

EKG changes/cardiac problems

ascending weakness, ileus

Question 19

hyperkalemia treatment

Answer 19

stabilization of cardiac muscles (IV Ca+)
Lowering serum K+
move K into cells (insulin, beta agonists, bicarb)
removing K+ (diuretics, resins, dialysis)

Question 20

Ca effect on K+ (mechanism)

Answer 20

antagonize membrane depolarization

Question 21

Insulin (& glucose) effect on K+ (mechanism)

Answer 21

Increase K+ uptake

Question 22

Bicarbonate effect on K+ (mechanism)

Answer 22

Increase K+ uptake

Question 23

Albuterol effect on K+ (mechanism)

Answer 23

increase K+ uptake

Question 24

Furosemide effect on K+ (mechanism)

Answer 24

removal of K+ in kidney

Question 25

K-exchange resin effect on K+ (mechanism)

Answer 25

Removal of K+ in GI tract

Question 26

Hypokalemia causes (3)

Answer 26

decreased intake increased excretion internal redistribution

Question 27

3 types of external losses of K+ (excretion)

Answer 27

GI, cutaneous, renal

Question 28

2 types of renal loss hypokalemia

Answer 28

normotensive | hypertensive

Question 29

2 types of normotensive hypokalemia disorders

Answer 29

with metabolic alkalosis | with metabolic acidosis

Question 30

4 types of normotensive hypokalemias with metabolic acidosis

Answer 30

diuretics (loop & thiazide) Prolonged vomiting, nasogastric suction Bartter's syndrome Gitelman's syndrome

Question 31

Gitelman's syndrome

Answer 31

normotensive hypokalemia with metabolic alkalosis transport problem in DCT (like thiazides)

Question 32

Bartter's syndrome

Answer 32

normotensive hypokalemia with metabolic alkalosis transport problem in TALH (like furosemide)

Question 33

4 types of hypokalemia in hypertensive disorders

Answer 33

hyperreninemia (renal artery stenosis or renin secreting tumor) primary hyperaldosteronism (Conn's syndrome) (adrenal hyperplasia or tumors) Cushing's syndrome (glucocorticoid excess) Congenital adrenal hyperplasia (enzymatic defect in cortisol biosynthesis)

Question 34

Clinical manifestations of hypokalemia (muscle, cardiac, smooth muscle, renal)

Answer 34

weakness, rhabdomyolysis EKG changes/arrhythmias-tachyarrythmias hypertension, Ileus rephrogenic dibetes incipidus

Question 35

4 levels of decreasing serum K+ EKG (including normal)

Answer 35

normal flat T wave prominent U wave (after T wave) depressed ST segment

Question 36

Hypokalemia Rx

Answer 36

K replacement (oral, IV) K+-sparing diuretics

Question 37

K+-sparing diuretics (2 types x 2)

Answer 37

ENaC sodium chanel inhibitors (amiloride, triamterene) MC antagonists (spironolactone, eplerenone)