Nephro - K - Online MedEd

Question 1

Normal K - values

Answer 1

3.5-5.5
Hospitalized patients: 4-5
Deranged K –> death (very narrow range of K)
Intact K is taken care by normal kidneys

Question 2

Hyperkalemia - differential

Answer 2

1) Low Aldo state - ACEi, ARB, aldosterone antagonists - side effects of increasing K
2) Iatrogenic - give K
3) Ingestion (i.e. citrus) - most likely with CKD
4) ESRD
5) Artifact - hemolysis

Question 3

Hyperkalemia - look for what testing?

Answer 3

EKG (K = potassium)
Hyperkalemia - peaked T waves, QRS widen
Can also cause heart blocks
-If not corrected, will get sine wave EKG, and might not recover

Question 4

Hyperkalemia - what to do first?

Answer 4

Recheck K+ - due to likely iatrogenic
If elevated on recheck –> get EKG
If EKG is bad –> need to intervene asap (emergent) - need to do everything (stabilize, temporize, decrease K)
If EKG is normal –> then this is a stable hyperkalemia (urgent) - decrease K

Question 5

So if patient has hyperK with EKG changes… what are the interventions?

Answer 5

1) Stabilize - give CaCl IV last a few minutes (stabilize cardiac myocytes)
2) Temporize - want to shift K into cells - does nothing to total body K (so heart can’t see it) - insulin and D50 (give insulin to shift, and D50 to compensate for glucose), can also give Na bicarb and Beta agonists - last hours
3) Decrease total body K - eliminate - through urine and stool - i.e. loop diuretics (furosemide for K through urine); kayexalate so eliminate K through stool/diarrhea; can also use dialysis (chronic therapy) - these take a long time; can do acute hemodialysis

Question 6

Hypokalemia differential - how does it occur

Answer 6

Renal losses - hyperaldo (renal artery stenosis, Conn syndrome), diuretics (loops, thiazides)
GI losses - vomiting, diarrhea

Question 7

Hypokalemia what to do first?

Answer 7

Check EKG
Some flattening of T waves
-But typically replenish K

Question 8

So low K… what test to do first?

Answer 8

Recheck blood K
Check EKG
But regardless will replete K
- In practice ppl will jump right to replete K

Question 9

Repleting K

Answer 9

Oral is better than IV
With peripheral line, cannot go faster than 10mg/hr
Central line: fastest 20mg/hr for fear of cardiac symptoms
10 mg of K will change 0.1

Question 10

What is the other lab value to check for hypokalemia

Answer 10

Magnesium

-Might be low, so replete with K