Diseases of K+ regulation

Question 1

What affect does insulin have on ECF K+ concentration?

Answer 1

Insulin causes the rapid shift of potassium into cells.

Question 2

What effect do catecholamines have on potassium?

Answer 2

Catecholamines are non selective beta blockers that affect B2 adrenergic receptors and prevent potassium from moving as it should.

Question 3

T or F?

GFR is a major player in potassium concentration

Answer 3

False

It’s a really minor player in potassium concentration until potassium concentration is really really low

Question 4

What is the net effect of furosemide (Lasix) on potassium concentration?

Answer 4

Furosemide can cause hypokalemia because it blocks the Na/K/2Cl receptor where 15% of potassium is reabsorbed.

It’s not just this 15% that is effected because it messes up the gradient and actually results in a dramatically increased excretion of potassium.

Question 5

What effect does hyperaldosteronism tend to have on potassium concentration?

Answer 5

Hyperaldosteronism is often associated with hypokalemia since Na is reabsorbed at a greater rate in response to aldosterone, and Na is exchanged with K in the principal cell where aldosterone works. Thus, more K excretion, lower K levels in the ECF.

Question 6

T or F?

Alkalosis and hyperkalemia are conditions that tend to cause on another.

Answer 6

False.

Alkalosis is connected to hypokalemia. When somone is alkalotic, hydrogen ions rush out to the ECF and those hydrogen ions are exchanged for potassium, thus ECF potassium is low because potassium gets moved into the cells.

Question 7

A patient presents to the ED with hypokalemia. What are some acute causes that you should think of?

Answer 7

Catecholamine excess-this is usually due to medications such as albuterol.

Stress

Insulin excess (causes increased shift of potassium into the cells)

Question 8

A patient presents to clinic for a routine check up and you find they are hypokalemic. You reason that it must be due to chronic causes. You do a urine test to check the urine levels of potassium. What are chronic causes of high and low urine potassium?

Answer 8

Low urine K=extra renal causes.

1) Diarrhea=metabolic acidosis
2) Normal serum pH=decreased K intake

High urine K (>20)=renal causes

1) Metabolic alkalosis–>hyperaldosteronism
2) Metabolic acidosis–>DKA, renal acidosis

Question 9

It’s a crazy night and you have 3 hypokalemic patients, all with different situations. There are no attendings to help you and the nurse is looking to you to tell her how to treat them. The first is asymptomatic with metabolic acidosis. The second is asymptomatic with metabolic alkalosis. The third is experiencing symptoms. How should you treat the 3 of them?

Answer 9

1) Asymptomatic+Met acidosis. Give K citrate or K bicarbonate.
2) Asymp.+Met alk. Give KCl+volume replacement if they aren’t hypertensive. If hypertensive give a K sparing diuretic.
3) Symptomatic: Give IV replacement of K and monitor their ECG because they might have arrhythmias that could lead to further problems.

Question 10

What are the major consequences of hypo/hyperkalemia? Which one is more likely to lead to cardiac events?

Answer 10

For both of them the consequences are neuromuscular and/or cardiac injury.

Hypokalemia is more likely to lead to cardiac events. As the serum K continues to decrease, the cardiac ECG gets progressively worse.

*In small group I was told that hypokalemia will actually cause the heart to beat faster.

Question 11

A patient comes into the ED, and based on history you expect they may be experiencing hyperkalemia. What should be your first step?

Answer 11

Order an EKG. If that comes back normal, then you can start to do a more formal work up and figure out what is causing the problem.

Question 12

What is a spurious hyperkalemia (also known as pseudohyperkalemia)?

What causes it?

Answer 12

It’s when you have have K in the test tube but not in the patient.

Can be caused by hemolysis, a tough blood draw, the tourniquet being on too long, or thrombocytosis.

Question 13

You suspect a patient has acute hyperkalemia due to cell shift. What are some potential causes of this?

Answer 13

1) Inadequate insulin to move K into cells (diabetes)
2) Meds that are inhibiting K movement (B2 blockers)
3) Ischemic body part (such as from rhabdomyolysis) which results in large amounts of K+ being released into the body
4) Potentially eating too much meat since K+ is abundant in skeletal muscle

Question 14

Your patient has a high total body potassium (TBK) which you know to be a chronic process. What could have caused this condition?

Answer 14

1) A K secretion problem in the CCT (you’ll see low urine K)
2) Adrenal insufficiency (if elevated renin but low aldosterone–remember that aldosterone leads to sodium reabsorption and potassium excretion)

Question 15

What is the hallmark on the EKG of hyperkalemia?

Answer 15

Peaked T waves.

Sine waves are the last step before they go into cardiac arrest.

Question 16

A patient comes in with hyperkalemia and EKG changes. List some of the potential treatment options.

Answer 16

1) Give calcium gluconate (not sure why it works but it does)
2) Give Na bicarb
3) Give insulin AND glucose (insulin to get K into cells, glucose to make sure blood sugar doesn’t drop too much)
4) Kayexalate – resin that binds K in the gut and removes it. This is the only treatment out of those listed that actually removes K from the body.
5) Give dialysis STAT (it usually takes a bit to do this so do the other stuff until you can start them on dialysis)

*CBIGK*

Question 17

What hyperkalemic value should worry you enough to start looking for EKG changes and potential treatment?

Answer 17

A potassium value greater than 6 (from lecture notes)