Hypokalemia

Question 1

Scheme for hypokalemia:

• broad cateogries can be due to __ loss, __ intake of K+, or __ __ (into cells).

two causes of incresed loss could be from:

1. __loss (urine loss
2. __ loss (Urine loss >__mmol)– form high CCD flow like __, or high CCD from potatssium (TTKG>__).
   - if the ttkg is over four, look at the ___, if it’s contracted or expanded/normal. If it’s normal, this could be due to changes in the ___ activation system.

two causes of transcellular shift into cells could be:

1. __ or beta __stimulation
2. __, __ production of __ syndrome.

Answer 1

Scheme for hypokalemia:

• broad cateogries can be due to increased loss, decreased intake of K+, or transcellular shift (into cells).

two causes of incresed loss could be from:

1. GI loss (urine loss <20 mmol/day)– from diarrhea or vomiting
2. Urine loss (Urine loss >20mmol)– form high CCD flow like polyuria, or high CCD from potatssium (TTKG>4).
   - if the ttkg is over four, look at the EABV, if it’s contracted or expanded/normal. If it’s normal, this could be due to changes in the RAS activation system.

two causes of transcellular shift into cells could be:

1. insulin or beta 2 stimulation
2. alkalemia, RBC production of refeeding syndrome.

Question 2

is the principle cell K+ channels/aldosterone/EnAC physiology at fault for her case?

Answer 2

Hypokalemia with ttkg > 4 is abnormal, blame the principal cell.

here, ttkg = 9.3

yes. the pricniple cell is at fault.
- recall that if the TTKG>4, you have to look at EABV. if it’s normal or higher, it’s becasuse of an aldosterone or renin system issue.

Question 3

positive and negative regulators of the nA+K+ ATPASE

Answer 3

stimulation: beta 2

inhibition : alpha 1 stim, digoxin

Question 4

positive and negative regulator of the na+/H+ exchanger

Answer 4

insulin and bicarb activates these exchagners

Question 5

appraoch to hypokalemia

Answer 5

1. interpret renal handling
2. then look for other sources of loss or circumstantial evidence of shift
3. then consider low intake (rarely the sole cause, our diet usually has enough K+)
4. clinical features and EKG changes determine severity of hypokalemia

Question 6

Reduced ECF [K+] makes the RMP more ___

Answer 6

Reduced ECF [K+] makes the RMP more electronegative. if there is less K, the K+ from inside the cell will leave.

Question 7

ECG findings of hypokalemia

Answer 7

1. T wave flattening
2. QT prolongation
3. U wave

Question 8

treatment of hypokalemia if there are life threatening complications at play (ex/ ECG changes)

Answer 8

• intravenous K+ 1mmol/min
• ECG monitoring. Adjust rate when K+ is above 3

Question 9

2 broad ways to address hypokalemia when there are non-life threatening complications

Answer 9

1. increase intake ORal/IV
2. Reduce losses (renally and GI )– reduce TTKG,
3. also stop the cause of any shifts

Question 10

2 ways to renally address K+ loss

Answer 10

1. ENAC blocker
2. Aldosterone blocker (spironolactone/potassium sparing)
   - if you prevent sodium from entering the cell, K+ will not need to leave the cell.