K+ Flashcards
K+ balance
Normal body stores in adult = 3000-4000 meq
98% is INTRACELLULAR
K decrease by 1 meq reflects 200-400 meq total body deficit
Function of K+
- protein and glycogen synthesis
- maintains RMP
- determines membrane excitability
Symptoms of Low and High K+
relates to the inability to generate APs in muscles
- cramps
muscle weakness
EKG changes and cardiac arrhythmias
EKG changes of HYPOkalemia
PR interval prolongation ST depression Flattened/inverted T waves U-waves QRS widening
EKG changes of HYPERkalemia
PR interval prolongation
Elevated T waves
Widened QRS
K+ distributes rapidly into cells
catecholamines and insulin increase activity of Na/K pumps and uptake into skeletal muscle and liver
Acidemia and K
K moves out of cell as H+ is buffered into cells
Alkalosis and K
K moves into cells and H+ is buffered out of cells
Determinants of K secretion by kidney
- Plasma [K]
- Urine flow in distal tubule
- Aldosterone
Hypokalemia due to increased entry into cells
Metabolic alkalosis
Hyperinsulinemia
Increased catecholamines
Hypokalemia due to GI loss
N/V, diarrhea, NG tube suction
Hypokalemia due to urinary loss
Diuretics, hypercalcemia, aldosterone, hypomagnesemia
Low urinary K with Hypokalemia
GI Loss
- acidosis = lower GI, laxatives/villous adenoma
- alkalosis - upper GI, vomitting
High urinary K with Hypokalemia
Kidney Loss
- acidosis = ketoacidosis
- alkalosis
- normotensive = vomitting
- hypertensive = renin mediated
Hyperkalemia causes
Renal failure
effective circulating volume depletion
hypoaldosteronism –> decreased renin-angiotensin
