Diuretics pt. 2 (Exam III) Flashcards
(29 cards)
What does H₂O movement look like in the DCT?
How much Na⁺ absorption occurs in the DCT?
- ↓H₂O movement
- very little Na⁺ absorption
What ion gets reabsorbed in the DCT?
How does this occur?
Ca⁺⁺ is reabsorbed by PTH (Parathyroid hormone)
Combination of which two diuretic classes would cause a massive H₂O loss and require hospitalized monitoring?
Loop Diuretics + Thiazides
Which Thiazide diuretic is prototypical?
HCTZ (Hydrochlorothiazide)
Where is the final site of Na⁺ reabsorption?
Which site is the most important for K⁺ secretion?
Collecting Tubule
Collecting Tubule
Where do mineralcorticoids (like Aldosterone) elicit their effects?
Cortex portion of Collecting Tubule
Which channel is responsible for reabsorbing Na⁺ from the collecting tubule back into the blood?
ENaC (Epithelial Na⁺ Channel)
What potentiates the ENaC channel to increase Na⁺ retention?
Aldosterone
Where is Cl⁻ reabsorbed into the blood?
How is Cl⁻ reabsorbed into the blood?
- Collecting Tubule
1. ENaC retains Na⁺
2. Less K⁺ driven out makes urinary lumen (-)
3. (-) charge drives Cl⁻ through paracellular route into blood.
Which two diuretic classes are K⁺-wasting?
Which wastes more K⁺?
Loop Diuretics and CA Inhibitors (Acetazolamide)
Acetazolamide
Name two K⁺-sparing diuretics and their mechanism of action.
Spironolactone - blocks aldosterone receptors
Amiloride - Inhibits ENaC, blocking Na⁺ movement and thus K⁺ movement.
Rate of _____ secretion is positively correlated with aldosterone levels.
K⁺
What are the primary uses for K⁺-sparing diuretics?
States of excessive mineralcorticoids
- Conn’s Syndrome (excessive edema)
- Ectopic ACTH Production.
What are secondary uses for K-sparing diuretics?
- CHF
- Nephrotic Syndrome
What are 3 contraindications to K⁺-sparing diuretics?
- Patient takes K⁺ supplement
- Patient on drugs affecting K⁺ levels
- Liver Disease
What is the most common result of K⁺-sparing diuretic toxicity?
What exacerbates this?
How can this be avoided?
- Hyperkalemia
- Renal Disease
- Toxicity avoided by administering K⁺-sparing drug with a loop diuretic, balancing K⁺ levels.
How does ADH increase H₂O reabsorption?
- ADH binds to receptor
- Aquaporin carrying vesicle merges with urinary cell membrane.
- H₂O has more aquaporins to move through
What would osmolality be at the very apex of the thick ascending limb?
100 mOsm/L
What drug directly inhibits ADH?
Conivaptan
What is the primary use of mannitol?
What is a secondary use of mannitol?
- Reduction of ICP
- Removal of renal toxins (acute hemolysis or after radiocontrast)
How does Mannitol elicit its effect?
Mannitol is essentially artificial osmolality, increasing urine volume by pulling H₂O towards it.
What would the effects of mannitol toxicity be on serum Na⁺ specifically?
- Initial ↓ serum Na⁺
- Secondary ↑↑↑ serum Na⁺
What would mannitol toxicity encompass?
Would this differ if the patient had renal failure?
- Dehydration
- ↑Na⁺
- ↑K⁺
If the patient had renal failure then ↓Na⁺
What diuretic can crystallize when given parenterally and must be given with an in-line filter?
Mannitol
