Clinical Implications - Evaluating Hypokalemia and Hyperkalemia in the patient

Question 1

What are the 3 sites that the body can lose K+?

Answer 1

1. Kidneys
2. GI tract
3. Skin

Question 2

What are the 2 diuretics that cause K+ loss from the kidney?

Answer 2

1. Furosemide

2. Thiazides

Question 3

At what sites do diuretics act on to induce K+ loss?

Answer 3

The distal-K+ secretory system

Question 4

What does the distal K+ secretory system consist of? (3)

Answer 4

1. ICT (initial collecting tubule)
2. CCT (cortical collecting tubule)
3. Proximal portion of MCD (medullary collecting tubule)

Question 5

What is another way K+ can be lost from the kidney aside from diuretics?

Answer 5

Individuals with renal tubule disorders or alterations in the renin-angiotensin-aldosterone system

Question 6

How can you lose K+ from the GI system? (2)

Answer 6

1. Diarrhea

2. Vomiting

Question 7

How can you lose K+ from the skin? (2)

Answer 7

1. Dehydration and perspiration from exercise

2. Lost fluid from severe burns

Question 8

What are some miscellaneous ways that the body can lose K+ aside from the kidney, GI tract, and the skin? (3)

Answer 8

1. Alkalosis
2. Catecholamine surge
3. Excessive insulin administration

Question 9

What is pica? What is a consequence of this?

Answer 9

A behavior where one consumes clay. The clay binds to the K+ and prevents it from reabsorption in the GI tract.

Question 10

What is pseudohyperkalemia?

Answer 10

False lab results that indicate hyperkalemia, but is actually from traumatic hemolysis of red blood cells during blood drawing.

Question 11

Why do hemolyzed red blood cells cause elevated plasma K+ levels?

Answer 11

Because their intracellular fluids have now been released into the blood (duh). Not specific to RBCs. Any other cell that releases its contents will cause this too.

Question 12

Would patients with myeloproliferative disorders (excessive generation of platelets and WBCs) exhibit a high or low plasma K+ concentration? Why?

Answer 12

High, because K+ is released during clot formation.

Question 13

If you have healthy kidneys, will excessive intake of K+ cause hyperkalemia?

Answer 13

Naww mayne

Question 14

The use of Digitalis (a Na/K pump blocker) would cause hyper- or hypo-kalemia?

Answer 14

HYPERkalemia

Question 15

What is the main cause of hyperkalemia?

Answer 15

Renal failure

Question 16

How do you temporarily treat severe hyperkalemia (conc. > 8mM) that causes changes in an ECG?

Answer 16

Administer the following:

1. Calcium gluconate
2. NaHCO3
3. Glucose
4. Insulin

Question 17

How does calcium gluconate treat severe hyperkalemia?

Answer 17

Ca2+ raises the threshold for action potentials and lessens membrane excitability.

Question 18

How does administration of NaHCO3, glucose, and insulin lower K+ concentration?

Answer 18

By moving them to intracellular fluid (fromt the ECF) inside cells

Question 19

In addition to temporary medications in treating hyperkalemia, how does one get rid of excess K+?

Answer 19

Administer a non-absorbable cation exchange resin

Question 20

What does a non-absorbable cation exchanger resin do?

Answer 20

Binds to K+ and because it is non-absorbable, carries it out of the GI tract (out of the body).

Question 21

Why do doctors use the temporary medications instead of just solely using resins?

Answer 21

Because resin takes a long take to take effect.

Question 22

For patients with end-stage renal failure, how do physicians get rid of excess K+?

Answer 22

Dialysis