Potassium homeostasis Flashcards
98% of potassium is intracellular or extracellular?
intracellular
what % shift in distribution of potassium can be lethal?
2%
what are the causes of hypokalemia?
- decreased intake
- increased entry into cells
- increased GI loss
- increased urinary losses
what are the symptoms of hypokalemia?
- muscle weakness
- rhabdomyolysis
- renal dysfunction
- hyperglycemia
how does hypokalemia manifest on ECG?
U waves
what are the treatment options for hypokalemia?
- treat underlying cause
- oral or IV K+
- KCl, K phos, K citrate, KHCO3, K acetate
when administering potassium the IV dose should not exceed what level?
10-20 mmol / hour
why use KCl when administering potassium?
- metabolic alkalosis is commonly associated with hypokalemia
- administration of KCl will help both the hypokalemia and the metabolic alkalosis
what drugs caused drug-induced hyperkalemia?
- NSAIDs
- ACEI
- aldosterone antagonists
- renin inhibitors
what are the EKG manifestations of hyperkalemia? severe hyperkalemia?
- hyperkalemia: peaking and narrowing of the T wave with a short QT interval
- severe hyperkalemia: widening of QRS, decreased amplitude, loss of P wave
what is the first change seen on the ECG in a patient with hyperkalemia?
tall peaked and symmetrical T wave
what is the best initial therapy for severe hyperkalemia (muscle weakness, EKG changes)?
antagonism of deleterious membrane action
what is the dosing for hyperkalemia / calcemia?
10 mL 10% Ca2+ gluconate over 2-5 minutes
what does glucose and insulin do to treat hyperkalemia?
shifts potassium into cells by increasing activity of Na/K ATPase
what does NaHCO3 do to treat hyperkalemia?
shifts potassium to intracellular space
