Diuretics

Question 1

What is the primary ion movement that occurs in the distal convoluted tubule?

Answer 1

Na-Cl exchanger
Na-Ca antiporter
Calcium reabsorption?

Question 2

How do Thiazide diuretics work?

Answer 2

Inhibit the Na-Cl exchanger in the distal tubule.
This activates Na-Ca anti porter & increases Ca reabsorption = increased serum calcium.

Question 3

Where do aldosterone antagonist diuretics work in the nephron?

Answer 3

Collecting duct

Question 4

Where do loop diuretics work in the nephron?

Answer 4

Ascending loop of Henle

Question 5

Where do Carbonic anhydrase inhibitors work in the nephron?

Answer 5

Proximal convoluted tubule

Question 6

Where do potassium-sparing diuretics work?

Answer 6

Collecting duct

Question 7

What is a mnemonic to remember the diuretics and site of action?

Answer 7

COLT-PA
Carbonic anhydrase inhibitors
Osmotic diuretics
Loop diuretics
Thiazide diuretics
Potassium-sparing diuretics
Aldosterone antagonist diuretics

Question 8

How does Acetazolamide work?

Answer 8

Carbonic anhydrase inhibitor
Alkalizes the urine by inhibiting bicarbonate reabsorption in the proximal tubule.

Question 10

When does myoglobin precipitate in nephron tubules?

Answer 10

When the pH is less than 5.6.

Question 11

Which diuretics would result in U waves on an EKG and why?

Answer 11

U waves suggest hypokalemia.
Only potassium-sparing diuretics increase potassium reabsorption.
Bumetanide (Loop diuretic)
Metolazone (Thiazide)

Question 12

Other hypokalemia considerations?

Answer 12

Flat or inverted T waves
ST depression

Other:
Skeletal muscle weakness
Enhanced effects of nondepolarizing neuromuscular blockers
Hypokalemia increases risk of Dig toxicity by increasing Digoxin binding on the myocyte as well a s increasing pharmacological activity.

Question 13

How does carbonic anhydrase work?

Answer 13

Bicarbonate accepts H+ to corm carbonic acid.
Carbonic anhydrase dissociates carbonic acid into CO2 and H2O which favors a concentration gradient where HCO3 moves from the PCT into the cells.
Carbonic anhydrase inhibitors disrupts this mechanism = less HCO3 reabsorbed.

Since H+ isn’t used to product carbonic acid it remains in the body.
This causes Chloride to be retained to maintain electroneutrality = non-gap hyperchloremic metabolic acidosis.
(Metabolic acidosis can be used to stimulate ventilation in patients with central sleep apnea)

Question 14

What are some conditions Acetazolamide is used to treat?

Answer 14

Acute mountain sickness
Periodic paralysis

Question 15

Which loop diuretics are associated with ototoxicity?

Answer 15

Furosemide
Ethacrynic acid

Question 16

What kind of diuretic is Indapamide?

Answer 16

Thiazide diuretic
Works in DCT

Question 17

What are some unique side effects of Thiazide diuretics?

Answer 17

Hyperglycemia
Hypercalcemia
Hyperuricemia