Hyperkalemia And Hypokalmeia Flashcards
What is the normal potassium range in the body?
3.5-5.0 mEq/L
**abnormalities in potassium leads to Disabled resting membrane potential for muscles (especially cardiac) ***
Hyperkalemia
Potassium >5.5
Causes:
1) cell death: Rhabdomyolysis, burns, crush injuries, tumor lysis syndrome, hemolysis, leukemia
2) acidosis: diabetic ketoacidosis, type 4 renal tubular acidosis, etc.
3) renal failure
4) medications or conditions that inhibits aldosterone release
- ACE/ARBs, Addison’s disease, etc.
5) medications that prevent potassium release or gain potassium
- succinylcholine, NSAIDs, spironolactone, potassium supplementation, BBs, etc.
6) DDIs: especially linsiopril and trimethoprim
Symptoms of hyperkalemia
Often asymptomatic
Symptoms:
- Palpitations
- parasthesia
- muscle weakness
- cramps
- rare cases = hyperkalemia
EKG changes with respect to levels of hyperkalemia
- 5 - 6.5
- peaked T waves - 5 - 7.0
- results in progressive paralysis of the atria
- P waves widens and flattens
- PR segment lengthens - 0 - 9.0
- prolonged QRS interval
- AV block with junctional escape rhythms are present
- “sine” wave may appear
> 9.0
- cardiac arrest
- Asystole or V fib.
- PEA will show very wide and bizzare complex rhythms
Treatment for hyperkalemia
1) To stabilize the cardiac membrane = Calcium cholride or calcium gluconate IV push
- for wide QRS only
- DOESNT decrease serum potassium
2) to shift potassium into cells as needed
= insulin, nebulized albuterol, bicarbonate or normal saline
- bicarbonate for severe acidosis only
3) to remove potassium from the body = hemodialysis, normal saline, furosemide, ion exchange resin
- for cardiac arrest and renal failure
- not as great for rhabdomyolysis, tumor lysis but can still use
Why do you give calcium chloride or gluconate in wide QRS hyperkalemia?
Stabilizes cardiac membranes and restores the electrical gradient
- cells can now actually fire action potentials
- will narrow the QRS and speed up heart rhythm
- very rapid onset
calcium chloride is 3x more concentrated than gluconate*
Why do we give insulin or nebulized albuterol in hyperkalemia patients?
To shift potassium into the cells and prevent acidosis
- if acidosis currently, also give sodium bicarbonate
give with 50% dextrose to help shift potassium in easier
can only give albuterol if the patient can withstand the tachycardia and has no history of this
What is sodium polystyrene sulfonate?
Helps fix hyperkalemia by chelating potassium ions and exchanging them for sodium ions
- often given with sorbitol also to induce diarrhea and quick excretion of potassium
be careful and monitor for hypernatremia
Hyperkalemia periodic paralysis and hypokalemia periodic paralysis
Inherited disorders that causes defect muscle sodium channels that cause excess potassium leaving muscles or staying in the muscles and entering blood stream
Symptoms:
- episodic generalized painless muscle weakness
- cold intolerance
- hyperkalemia = cant tolerate high potassium food (or symptoms arise at this point)
- hypokalemia = vigorous exercise or high carbohydrate meals
Treatment in hyperkalemia
- acute = BB agonist (albuterol)
- prophylaxis = carbonic anhydrous inhbitor (acetazolamide) and thiazaide diuretics
Treatment in hypokalemia
- acute = potassium injections
- chronic = spironolactone and carbonic anhydrase inhibitors
What is the most common DDI seen for hyperkalemia
Lisinopril with trimethoprim or triamterene
Hypokalemia
Serum potassium <3.5
VERY common in hospitalized patients who are on diuretics
Also frequently coexists with hypomagnesemia
(This is because magnesium defect causes increased potassium secretion in DCT)
Other common causes
- GI loss = diarrhea of laxative abuse
- renal loss = diuretics, renal tubular acidosis, hyperaldosteronism
- endocrine loss = treatment of diabetic ketoacidosis
- alkalosis
Cardiac effects with hypokalemia
1st/2nd/3rd heart blocks
PACs and PVCs
Ventricular tachycardia
Torsades de pointes/ v. Fib
ECG characteristics:
- prolongation of QT and PR intervals
- flattening and inversion of T waves
- Uwaves become present
What is normal pH?
7.36 -7.44
Barter and gitelman syndrome
Both are genetic conditions that result in a lack of sodium and chloride reabsorption by the kidney which stimulates RAAS
- also causes K+/H+ secretion in urine = metabolic alkalosis
- urine has high chloride
- barter = loop of Henle affected
- shows urine calcium as NORMAL
- Gitelman = DCT affected
- shows urine calcium as LOW
Treatment of hypokalemia
If potassium is >3.0
- potassium chloride tablets only
If potassium is <3.0
- IV KCL and replace magnesium if needed
- get EKG also to monitor as well
