Potassium Worksheet

Ranges of potassium that are life threatening

>6 mEq/L and < 3 mEq/L (hypokalemia)

What is the life-threatening range for hyperkalema?

8 mEq/L

How does hyperkalemia affect the cardiovascular system?

It can cause the cardiac conduction to break down and get a sine wave instead of a normal QRS.

_______ potassium levels are seen more infrequently

Low

What hormone/medication can affect potassium?

Insulin and B-agonists

How do insulin and B-agonists work with potassium?

They push potassium into cells by indirectly stimulating Na-H antiporter, and by directly stimulating Na-K-ATPase pump

What does aldosterone affect?

Excretion, not intracellular shifting

What happens to potassium in the nephron tubules?

Potassium is secreted in the collecting duct

What hormone controls the fine tuning of potassium levels?

Aldosterone controls potassium excretion by stimulating Na-K-ATPase, and inserting Na+ and K+ in the luminal membrane

Where does aldosterone come from?

Adrenal gland

What stimulates the release of aldosterone?

High serum potassium levels stimulate angiotensin II via the RAAS system

What are some shift situations that lead to hyperkalemia (where the potassium that is normally in the cells gets shifted to the extracellular fluid and blood)?

1. Hyperglycemia

2. Cell breakdown

3. Acidosis

4. Drugs

How would hyperglycemia lead to hyperkalemia?

Osmotically, through a lack of insulin

How would cell breakdown lead to hyperkalemia?

Catabolism, ischemia and pseudohyperkalemia

How would drugs lead to hyperkalemia?

Beta-blockers and digoxin inhibit Na-K-ATPase

How does decreased GFR contribute to hyperkalemia?

It results in less filtered potassium and fewer nephrons to secrete it, impairing secretion

What factors in the distal nephron can lead to hyperkalemia?

Decreased distal delivery of Na⁺ and water, and impaired aldosterone action

What are some ways that aldosterone levels can be altered abnormally?

Drugs, like ACE inhibitors (lisinopril), angiotensin receptor blocker (ARBs) like losartan, aldosterone antagonists like spironolactone, NSAIDs, B-blockers, heparin, cyclosporin, tacroliums

What are some other ways that aldosterone levels can be altered abnormally other than drugs?

Hypoadrenalism like Addison’s disease, and aldo resistance

What are some general treatments for hyperkalemia that they use in the ER?

If it is an emergency, stop medications, give IV fluids

1. Stabilize the heart with IV calcium gluconate,

2. Shift potassium into cells using insulin with glucose, B-agonists (albuterol), and sodium bicarbonate

3. Remove potassium from the body via loop diuretics, ion exchange resin, or dialysis

What are the two most common causes of hypokalemia?

1. GI Losses, diarrhea (acidosis), vomiting (alkalosis)

2. Kidney Losses: diuretics (hyperaldosteronism)

What are the renal causes of hypokalemia?

1. Carbonic anhydrase inhibitors

2. Osmotic diuretics

3. Loop diuretics

4. Thiazide diuretics

What are the potassium-sparing diuretics?

1. Amiloride

2. Triamterene

3. Spironolactone

4. Eplrenone

How does Addison’s disease cause low aldosterone?

It causes hyperkalemia because it leads to low aldosterone levels, impairing renal potassium excretion