Potassium/K+ Balance (Popham) - W3

Question 1

What is the normal serum/plasma K+?

K+ decrease by 1 reflects total body deficit of?

Answer 1

• 4-5 meq/l
• decrease by 1meq reflects 200-400 meq total body deficit

Question 2

What are the functions of the K+?

Answer 2

• role in protein & glycogen synthesis
• matainis resting membrane poteintal in muscle cells and neurons w/NA/K/ATPase
• determines membrane excitability
• allows action potentials to be generated

Question 3

What physcial symptoms do you see with hypokalemia?

What EKG changes do you see?

Answer 3

• cramps
• muscle weakness/paralysis
• EKG
  
  • PAC
  • PVCs
  • bradycardia
  • atrial or junctional tachycardia
  • AV block
  • v-tach/v-fib

Question 4

5 EKG changes of hypokalemia

Answer 4

• PR interval prolongation
• ST depression
• flattened or inverted T waves
• U waves
• QRS widening

Question 5

EKG changes of hyperkalemia

Answer 5

• PR interval prolongation
• Elevated T waves
• widened QRS interval

Question 6

What can modify the effects of K+ on the action potential?

Answer 6

• Hypercalcemia - increases threshold potential to protect against hyperkalemia
• metabolic acidosis exacerbates hyperkalemia - K+ released from cell
• chronic tolerated better
• digoxin causes HYPERkalemia

Question 7

what is the major route of potassium elimination?

Answer 7

kidneys

some lost in stool or sweat

Question 8

3 determinants that increase K+ secretion

Answer 8

• plasma K+ concentration
• urine flow in distal tubule
• aldosterone

Question 9

6 causes of hypokalemia

Answer 9

1. decreased intake
2. increased entry into cells
3. increased GI losses
4. increased urinary losses
5. increased sweat losses
6. dialysis

Question 10

What is it rare to get hypokalemia from?

Answer 10

inadequate diet

unless poverty, protein diet supplements, hypertension diuretics, clay ingestion

Question 11

What can cause hypokalemia through increased entry into cells?

Answer 11

• Metabolic acidosis
• hyperinsulinemia
• increased catecholamines/beta agonists

Question 12

What are causes of hypokalemia through GI losses?

Answer 12

• nausea vomitting
• NG tube suction
• diarrhea/intestinal fistual/tube drainage

Question 13

What are causes of hypokalemia due to increased urinary losses

Answer 13

• diuretics, salt wasting, polydipsia/polyuria
• hypercalcemia (increased distal flow)
• mineralcorticoid excess (aldosterone)
• hypomagnesium (no inhibition on K+ into urine)
• high NaHCO3

Question 14

Cause of low urinary K and acidosis

Answer 14

Lower GI losses

Question 15

Cause of LOW urinary K and alkalosis

Answer 15

upper GI losses (vomitting)

Question 16

HIGH urinary K and acidosis

Answer 16

ketoacidosis (type I or II RTA)

Question 17

HIGH urinary K and alkalosis cause

Answer 17

normotensive = vomitting, diuretics, Bartters syndrome

hypertensive: low aldosterone, high aldosterone (adrenal adenoma

high renin: Cushings, diuretics, reninoma

Question 18

What are some complications of hypokalemia?

Answer 18

• muscle weakness
• cramps
• cardiac arrhythmias
• rhabdomyolysis
• renal dysfunction
• hypertension

Question 19

3 causes of hyperkalemia

Answer 19

• increased intake: oral or IV
• shift: movemenet fluid cells into extracellular fluid
• decreased urinary excretion