Clinical Perspective - Disorders of Potassium

Question 1

True/False. Aldosterone excess is a cause of hypokalemia.

Answer 1

True - aldosterone increases Na reabsorption via ENaCs, thus increasing K+ secretion

Question 2

How is most K+ excreted from the body?

Answer 2

90% via urina, 10% via stool

Question 3

What are common causes of hyperkalemia?

Answer 3

Hyperosmolarity, low insulin, non-anion gap metabolic acidosis, NSAIDs

Question 4

What foods have the highest K+ content?

Answer 4

Dried figs, molasses, seaweed

Question 5

Where is most K+ stored in the body?

Answer 5

Intracellularly - primarily in myocytes

Question 6

Where is most K+ reabsorbed in the kidney?

Answer 6

PCT

Question 7

What changes would be seen on an ECG of a patient with hypokalemia?

Answer 7

ST depression, flatted T wave, U wave

Question 8

What drug is given to stabilize the heart rhythm in hyperkalemia?

Answer 8

Calcium Gluconate - note this does not treat hyperkalemia, only prevents arrhythmias

Question 9

What is the treatment for Bartter’s syndrome?

Answer 9

ACEI or ARB

Question 10

What is the treatment for Liddle’s syndrome?

Answer 10

Amiloride, triameterne (K+ sparing diuretics)

Question 11

What findings would be seen on an ECG of a patient with hyperkalemia?

Answer 11

Prolonged PR, peaked T waves, sine waves, asystole

Question 12

What is the treatment to remove excess K+ in cases of hyperkalemia?

Answer 12

Lactulose, loop diuretics, dialysis

Question 13

This autosomal recessive disease affects the thick ascending loop, causing NaCl wasting, hypokalemia, and metabolic alkalosis.

Answer 13

Bartter’s Syndrome

Question 14

This autosomal recessive disease affects the DCT causing mild NaCl wasting and hypokalemia.

Answer 14

Gitelman’s Syndrome

Question 15

What is the only location of K+ excretion in the kidney?

Answer 15

Collecting duct

Question 16

True/False. A patient with decreased kidney function is at higher risk of hypokalemia.

Answer 16

False - they are at risk of hyperkalemia. This is because the kidneys excrete 90% of K+ via urine

Question 17

What is the treatment of hypokalemia?

Answer 17

Replete Mg (if low) and K+ supplementation

Question 18

What drugs are used to increase intracellular K+ uptake?

Answer 18

Insulin, Albuterol - note these are only temporary fixes and do not remove excess K+ from the body

Question 19

Liddle’s and Bartter’s syndromes both cause hypertension. How do the causes differ?

Answer 19

In Liddle’s syndrome, HTN is due to NaCl reabsorption and H2O retention.

In Bartter’s syndrome, HTN is due to NaCl wasting and hyperactivation of the RAAS system

Question 20

This disease causes persistent ENaC activation in the collecting duct leading to hypertension and hypokalemia.

Answer 20

Liddle’s Syndrome