#32 - Potassium Flashcards
Which 5 things can change the INTERNAL regulation of potassium?
- insulin
- catecholamines
- acid/base balance
- plasma tonicity
- cell lysis/proliferation
T/F: EKG is an important part of the workup in potassium disorders.
TRUE - Cardiac death can occur due to altered potassium, and urgent intervention may be needed. You can track changes via serial EKG monitoring.
Goals of therapy for hyperkalemia - 3
- stabilize the cardiac membrane
- shift potassium intracellularly
- remove excess K+
T/F: Hyperkalemia, but not hypokalemia, can lead to cardiac dysrhythmias.
False. They both lead to cardiac dysrhythmias.
T/F 2/3 of patients die if their hyperkalemia is not treated.
True.
Normal range for potassium
3.5-5.0 mEq/L
T/F The Potassium gradient is largely maintained by the Na/K ATPase pump, which pumps K out of the cell.
False. The pump pumps K+ INTO the cell (98% of K+ in the body is inside cells)
What does “internal balance” of K+ refer to?
the distribution of K+ between intracellular fluid and extracellular fluid
What does “external balance” of K+ refer to?
regulation of potassium through K+ intake and excretion (mainly kidney)
Which cell is most responsible for K+ excretion in the kidney?
Principle cell, in the collecting duct.
K+ excretion in the kidney is dependent on 2 things:
- distal sodium delivery
- aldosterone
Describe excretion of K+ in the kidney, including role of Na and aldosterone
sodium arrives in collecting duct. Sodium comes into the principal cell through ENaC,–>
charge in urine becomes negative—> negative charge attracts which pulls potassium out of the principal cell into the lumen.
Aldosterone activates ENaC (Na channel), and K channel, helping both steps of the process.
Insulin effect on K+
Insulin lowers K+
Insulin activates the Na/K ATPase pump, pushing K inside the cells of the liver/ muscle.
Catecholamines effect on K+
Catecholamines lower K+
Norepinephrine and epinephrine activate the Na/K ATPase through B2 adrenergic receptors.
How does being acidotic affect your K+?
Raises K+
If your bloodstream is acidotic, it will send H+ ions inside the cell to reduce acidity, in exchange for K+ ions, which leak out of the cell, raising your K+.
