Potassium disorders Flashcards
What are some EKG changes of hypokalemia?
PR prolongation ST depression T wave flattening/inversion U wave elevation QRS widening
What is normal serum potassium concentration?
4-5 mEq/L
What are some EKG changes to hyperkalemia?
PR interval elongation
T wave elevation
Widened QRS
What effect does calcium concentration have on hyperkalemia?
Increased calcium increases threshold potential, decreases effects of hyperkalemia
What does hyperkalemia do to the threshold potential?
Decreases it
What does metabolic acidosis do to serum potassium concentration?
Causes hyperkalemia as H+ is buffered into the cell and K+ is pumped out
What does digoxin do to serum potassium levels?
Causes hypokalemia
What is the effect of insulin and catecholamines on serum potassium levels?
Lower the levels as potassium gets shunted into cells
What protein do insulin and catecholamines increase the activity of, effecting the potassium levels?
Na/K ATPase
What does aldosterone do to potassium levels?
Decreases them by upregulating BK and ROMK channels in the collecting tubule, at the same time upregulating NaK ATPase on the basolateral side
What are six broad categories of hypokalemia causes?
Decreased dietary intake Increased entry into cells Increased GI losses Increased urinary losses Increased sweating Dialysis
What are the three main causes of cellular intake induced hypokalemia?
Metabolic acidosis
Hyperinsulinemia
Increased catecholamine/beta agonist levels
What are four ways in which urinary losses can lead to hypokalemia
Increased distal tubule flow (diuretics, salt-wasting nephropathy, polydipsia)
Hypercalcemia (increased distal flow)
Mineralocortocoid excess (increased aldosterone levels)
Hypermagnesemia
What are some major complications of hypokalemia?
Rhabdomyolysis Muscle cramps/weakness Arrhythmias Renal disfunction Hypertension
What are some causes of hyperkalemia?
Increased intake
Shift from cells to serum
Decreased urinary excretion
Under what situations is hyperkalemia induced by cellular shunting?
Muscle breakdown
Insulin deficiency with hyperglycemia
Metabolic acidosis
What are the main causes of hyperkalemia via decreased urinary excretion?
Kidney failure
Circulating volume depletion
Hypoaldosteronism
What three steps should be taken to treat hyperkalemia?
- Treat membrane (Induce hypercalcemia)
- Shift K+ into cells
- Get rid of excess K+
How do you induce shift of K+ into cells?
Insulin/catecholamine injection
Concentration gradient (glucose)
HCO3
How do you remove excess K+?
Diuretics
Kayexylate
Dialysis
