Potassium

Question 1

Normal range of potassium in the ECF

Answer 1

3.5–5.0 mmol/L.

Question 2

Most of the body’s potassium is in the:

Answer 2

ICF

Question 3

What regulates potassium in and out of cells?

Answer 3

The sodium-potassium pump

Question 4

The ratio of ECF to ICF potassium is critical for:

Answer 4

Resting membrane potential of neurons and muscle cells.
Transmission and conduction of nerve impulses.
Maintenance of normal cardiac rhythms.
Skeletal and smooth muscle contraction.

Question 5

What is the primary source of potassium intake:

Answer 5

Diet

Question 6

Main route for potassium excretion:

Answer 6

Kidneys

Question 7

Factors influencing potassium excretion

Answer 7

Sodium retention, increasing potassium loss
Large urine volume, can cause excessive potassium excretion
Kidney dysfunction

Question 8

Factors causing K+ to move from ECF → ICF (resulting in hypokalemia)

Answer 8

Insulin - promotes potassium uptake by cells
Alkalosis - H+ ions leave cells, and potassium enters to maintain charge balance
B-adrenergic stimulation (e.g. catecholamine release in stress) - activates sodium-potassium

Question 9

Factors causing K+ to move from ICF → ECF (resulting in hyperkalemia)

Answer 9

Acidosis - H+ ions enter cells and potassium exists to maintain charge balance
Trauma to cells - releases intracellular potassium
Exercise - causes temporary potassium release from muscle cells.

Question 10

What is the most common cause of hyperkalemia?

Answer 10

Renal failure

Question 11

Why is hyperkalemia common in patients with massive cell destruction (e.g., burn or crush injury, tumour lysis)

Answer 11

Cells rupture and potassium is leaked into the bloodstream

Question 12

Adrenal insufficiency leads to which imbalance of K+?

Answer 12

hyperkalemia

Question 13

What may be the first symptoms of hyperkalemia?

Answer 13

Leg cramping

Question 14

Three broad categories of causes of hyperkalemia

Answer 14

Excessive potassium intake
- Excessive/rapid parenteral administration
- Potassium-containing drugs
- Potassium-containing salt substitutes

Shift of potassium out of the cells
- Acidosis
- Tissue catabolism (e.g. sepsis, burns)
- Crush injury

Failure to eliminate potassium
- Renal disease
- Potassium-sparing diuretics
- Adrenal insufficiency
- ACE inhibitors

Question 15

Three broad categories of causes of hypokalemia

Answer 15

Potassium loss
- GI losses
- Renal losses
- Skin losses
- Dialysis

Shift of potassium into cells
- Increased insulin
- Alkalosis
- ↑ epinephrine

Lack of potassium intake
- Starvation
- Diet with low K+
- Failure to include K+ in NPO patient

Question 16

Clinical manifestations of hyperkalemia

Answer 16

Irritability
Anxiety
Abdominal cramping + diarrhea
Weakness of lower extremities
Paresthesias “pins & needles”
Irregular pulse
Cardiac standstill if hyperkalemia is sudden/severe

High & tight

Question 17

Clinical manifestations of hypokalemia

Answer 17

Fatigue
Muscle weakness
Leg cramps
N+V
Flabby muscles
Decreased reflexes
Weak, irregular pulse
Polyuria
Hyperglycemia

Low & slow

Question 18

Treatment of hyperkalemia

Answer 18

Eliminate oral and parenteral potassium intake

Increase elimination of potassium
- Diuretics
- Dialysis
- Increased fluid intake can enhance renal potassium elimination

Forcing potassium from the ECF → ICF
- Administration of IV insulin (along with glucose so the patient doesn’t go hypoglycemic)
- Administration of IV sodium bicarbonate in the correction of acidosis

Reversing the membrane effects of the elevated ECF potassium by administering calcium gluconate IV
- Calcium ions can immediately reverse the effect of the depolarization of cell excitability

Question 19

Most common cause of hypokalemia

Answer 19

Abnormal losses of potassium via either the kidneys or the Gi tract

Question 20

Hypokalemia; losses through kidneys and GI tract

Answer 20

Kidneys
- elevated diuresis; elevated aldosterone levels

GI tract
- Diarrhea
- Laxative abuse
- Vomiting
- Ileostomy drainage

Question 21

Treatment of hypokalemia

Answer 21

Treat the underlying cause

Question 22

Examples of underlying cause of hypokalemia

Answer 22

Vomiting, chronic diarrhea, or both
Certain medications
Excessive sweating (Does the pt have CF?)
Undereating or malnutrition
Kidney disease, diabetic ketoacidosis

Question 23

When restoring K+ in hypokalemia, we can use __ or __

Answer 23

IV medication or increase dietary intake

Question 24

Safety Alert for KCl IV

Answer 24

Must always be diluted
Never give KCl via IV push or in a concentrated bag
IV bags should be inverted several times to ensure even distribution in the bag
Never give KCl to a hanging bag, to prevent bolus dose