05.08 - K Balance (Showkat) - PP, No reading Flashcards Preview

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Flashcards in 05.08 - K Balance (Showkat) - PP, No reading Deck (83):
1

Daily intake and output of K

100 mEq/d in; 90-95 out kidney, 5-10 out GI

1

3 Factors Affecting K Secretion

(1) [K] across membrane - depends on serum [K]; (2) Electrical gradient deteremined by Na delivery to DT; (3) K permeability of luminal membrane determined by Aldosterone

2

3 Groups of Causes of Hyperkalemia

(1) Excessive K intake; (2) Dec Renal Excretion; (3) Internal Redistribution

3

How does vomitting affect K balance

Hypokalemia due to increased Aldosterone

3

K imbalance in Congenital Adrenal Hyperplasia

Hypokalemia

4

How is K reabsorbed in ThickALOH, and what else travels thru this route?

Paracellular Diffusion, also Na+, Ca2+, Mg+

5

5 Causes of Internal Redistribution of K leading to HyperK

Insulin Def., B2 blockade, Hypertonicity, Acidemia, Cell lysis

6

How does NG suction affect K balance

Hypokalemia due to increased Aldosterone

6

Three ways to move K outside body in Hyperkalemia Tx

Diuretics, Resins (cation exchange), Dialysis

7

What eliminates effect of DT flow rate on K secretion

Low K diet

8

Skeletal muscle clinical manifestations of Hypokalemia

Weakness, Rhabdomyolysis

9

Which has greater effect on K: Metabolic acidosis due to Organic Acids or Mineral Acids

Mineral Acids

9

K imbalance in Cushing's

Hypokalemia

9

When are diuretics usually used for hypokalemia

K sparing in cases of chronic hypokalemia

11

K-related channels in ThickALOH

NaK2Cl on luminal border; K channel on luminal border; Na-K ATPase on basolateral border

12

What channel does Bartter's affect?

Na-K-2Cl

13

What determines the number of K channels in luminal membrane of DT/CD

Aldosterone

13

What 3 factors promote K movement across cells

Plasma [K], Insulin, Epinephrine

15

Hypoaldosteronism will cause what K imbalance

Hyperkalemia (decreases secretion)

16

Metabolic Acidosis causes what change in K

H+ enters cell, K exits

16

Three ways to move K inside cells in Hyperkalemia tx

Insulin, Beta agonists, Bicarb

17

K imbalance in Renal Artery Stenosis

Hyper-reninemia - Hypokalemia

19

2 Actions of Aldosterone in Principal cells

(1) Adds ENaC (in) and ROMK (out) channels to luminal surface; (2) Stimulates Na-K pump -> Creates electronegativity -> Reabsorption of Na thru epithelial channel (ENaC)

20

Major site of K reabsorption

PT

21

Causes K movement into cells - Simtulates Na-H exchange - This activates Na-K ATPase

Insulin

21

Clincial manifestations of Hyperkalemia result primarily from

Depolarization of resting Vm in myocytes and neurons

21

What beta agonist is used for Hyperkalemia? How does it work?

Albuterol - Activates Na-K pump via beta 2 receptor

21

K imblanace in Renin-Secreting Tumor

Hypokalemia

22

Onset and duration of Kayexalate in Hyper K tx

2-3 hours, 4-6 hours

23

What K imbalance is caused by decreased plasma osmolality

Hypokalemia

24

How does increase in Plasma Osmolality change K balance

(1) Fluid shifts out cell and drags K with it; (2) Loss of water causes conc. gradient, K exits down gradient passively

26

How does insulin affect K movement

Causes movement into cells - Simtulates Na-H exchange - This activates Na-K ATPase

26

At what plasma [K] will you see sine wave morphology

12 mEq/L

27

K imbalance in Bartter's, Gitelman's

Hypokalemia

28

Rapid infusion of K can cause

Cardiac Arrhythmias

29

K imbalance in Conn's Syndrome

Primary Hyper-Aldosteronism - Hypokalemia

31

What potentiates the affect of DT flow rate on K secretion

High vs Low K diet

31

What K imbalance is caused by renal failure

Hyperkalemia - Impaired secretion

31

EKG changes in Hyperkalemia

(1) Peaked T wave; (2) Wide QRS, Short QT, Long PR; (3) Further wide QRS, absent P wave; (4) Sine Wave

33

4 significant locations of intracellular K

Muscle, Liver, RBC, Bone

34

At what plasma [K] will you see peaked T wave

6 mEq/L

34

Renal clinical manifestations of Hypokalemia

Nephrogenic Diabetes Insipidus

35

Onset and duration of Furosemide in HyperK tx

5 min, 2 hours

37

How does Hyperaldosteronism affect K balance

Hypokalemia due to increased Aldosterone

38

Major site of K secretion

CD

40

How does rapid cellular proliferation affect K balance?

Rapid intake -- Hypokalemia

41

Onset and duration of Ca2+ for HyperK tx

1-3 mins, 30-60 mins

42

2 classes of K-sparing diuretics used for Hypokalemia

(1) Aldosterone R Blockers; (2) ENaC inhibitors

42

Inhibiting this channel will inc. postive charge in lumen, prevent K secretion

ENaC

43

Onset and duration of Albuterol for HyperK tx

30 mins, 2-4 hours

45

How does too much Na reabsorption affect K secretion

Not enough Na enters ENaC on Principal cells, and there is a small electochemical gradient that is necessary to drive K secretion

46

At what plasma [K] will you see wide QRS, short QT, long PR?

8 mEq/L

48

Prolonged depolarization from Hyperkalemia decreases

Na permeability thru inactivation of V-gated Na channels - Reduction in membrane excitability

50

How does alpha receptor affect K movement

Inhibits Na-K ATPase, so prevents movement of K into cells

51

How do ENaC inhibitors tx Hypokalemia

Inhibiting this channel will inc. postive charge in lumen, prevent K secretion

53

How does High K diet affect amount of K secreted for given DT flow rate

Increases

55

How do Bartter's and Gitelman's affect K balance?

Hypokalemia due to increased distal Na delivery

56

4 Causes of Hypokalemia due to Internal Redistribution

Insulin excess, Catecholamine excess, Alkalemia, Cell proliferation

57

How do acid base disturbances affect K

Changes in extracellular pH produce reciprocal shifts in H+ and K+ across membrane

58

Smooth muscle manifestations of Hypokalemia

HTN, Ileus

60

Stimulates Na-K ATPase via B2 receptors - Move K intracellularly

Epinephrine

61

K imbalance in Prolonged Vomitting, NG suction

Hypokalemia

62

Which have greater effect on K: metabolic or respiratory acid base disturbances

Metabolic

64

Onset and duration of Insulin for HyperK tx

30 mins, 4-6 hours

65

How are diuretics used to tx Hypokalemia

K-sparing diuretics increase K reabsorption

66

K imblanace in Uretral diversion

Hypokalemia

66

Most common clinical cause of Hypokalemia

Exogenous glucocorticoid excess - Steroid Admin

68

K imbalance in Primary Hyper-Aldosteronism

Hypokalemia

69

What K imbalance is caused by increased plasma osmolality

Hyperkalemia

70

Alkalosis causes what change in K

H+ exits cell, K enters

71

EKG changes in Hypokalemia

(1) Flat T wave; (2) Prominent U wave; (3) Depressed ST segment

72

How does Epi affect K movement

Stimulates Na-K ATPase via B2 receptors - Move K intracellularly

73

How and why does distal tubular flow rate affect K secretion

Increase flow = Inc secretion Na delivery to DT

74

How do diuretics (Loop, Thiazide) affect K balance

Hypokalemia due to increased distal Na delivery

75

How is K usually given clinically

KCl, KPO4 - KCl tab or mixed with IV fluids

76

First-line tx of Hyperkalemia

Ca2+ (doesn't lower K, just counters)

77

Amount of Intracellular K

3300 mEq

78

How does Beta receptor affect K movement

Stimulates Na-K ATPase, so moves K into cells

79

How does Na reabsorption affect K Secretion

If more Na is delivered distally, it enters thru ENaC channels in Principal Cells and creates electrochemical gradient favor K secretion

80

Why and How does beta blockade affect K balance

B2 receptors activate Na-K -> Without activation, K not taken up into cell -> Hyperkalemia

81

Hyperaldosteronism will cause what K imbalance

Hypokalemia (increases secretion)

82

4 causes of decreased renal K secretion

Kindey Failure, DT dysfxn, Dec DT flow, Hypoaldosteronism

83

If there is a deficiency in insulin, what channel is impaired and what ion is dysregulated?

Na-K pump is impaired, Elevated K in ECF