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FF Renal > Diuretics > Flashcards

Diuretics Flashcards

1
Q

Your patient is starting on a potassium-sparing diuretic and is worried about side effects. What do you tell him?


A

Side effects include hyperkalemia (leading to arrhythmias) and endocrine effects with spironolactone (gynecomastia and antiandrogen effects)

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2
Q

____ (Loop/Thiazide) diuretics increase calcium excretion; ____ (loop/thiazide) diuretics decreases it.


A

Loop; thiazide


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3
Q

What mechanism underlies volume contraction alkalosis?


A

Volume contraction increases angiotensin II activity, increasing proximal tubule H+/Na+ exchange and HCO3- reabsorption


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4
Q

Where does parathyroid hormone increase calcium reabsorption in the nephron?


A

Distal convoluted tubule


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5
Q

A patient of yours with a history of gout and diabetes wants to start hydrochlorothiazide for hypertension. You refuse. Why?


A

Hydrochlorothiazide increases levels of both uric acid and glucose, which may worsen the patient’s gout and diabetes, respectively


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6
Q

Fill in the blanks (thiazides/K+-sparing diuretics/loop diuretics/acetazolamide): ___ and ___ raise blood pH; ___ and ___ lower blood pH.


A

Loop diuretics and thiazides raise blood pH; acetazolamide and K+-sparing diuretics lower blood pH


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7
Q

What are three (general) clinical uses for loop diuretics?


A

To treat edematous states (congestive heart failure, cirrhosis, nephrotic syndrome, pulmonary edema), hypertension, and hypercalcemia


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8
Q

A patient starts a potassium-sparing diuretic. What are the main electrolytes absorbed and secreted at the site where this drug acts?


A

Potassium-sparing diuretics act on the collecting tubule, where NaCl (reabsorbed), K+ (secreted), and H+ (secreted) are exchanged


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9
Q

A patient taking torsemide is noted to have dilated renal afferent arterioles. This effect is blocked by NSAIDs. What is happening?


A

Torsemide, a loop diuretic, dilates the afferent arterioles by stimulating prostaglandin E (PGE) release, an effect inhibited by NSAIDs


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10
Q

A patient starts taking acetazolamide for mild altitude sickness. What is the mechanism of action of this drug?


A

It acts as a carbonic anhydrase inhibitor, causing self-limited sodium bicarbonate diuresis and a reduction in total-body bicarbonate stores


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11
Q

A patient takes mannitol. On which segments of the nephron does an osmotic agent such as mannitol exert its diuretic effects?


A

Proximal straight tubule and the thin descending loop of Henle


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12
Q

A patient takes a diuretic for increased intracranial pressure. What is the drug and its mechanism of action?


A

Mannitol, an osmotic diuretic, which increases tubular fluid osmolarity and therefore urine flow rate (also acts on intraocular pressure)


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13
Q

A patient of yours starts chlorthalidone for hypertension and notes fewer kidney stone attacks. Why might this be happening?


A

Hydrochlorothiazide increases DCT reabsorption of calcium, which reduces the likelihood of calcium-containing stones in the urine

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14
Q

In a patient on diuretics, labs show a high urine sodium and a low serum sodium. Can you pinpoint which diuretic(s) may be responsible?


A

Except for acetazolamide, no (all diuretics can cause this effect, so this is a nonspecific finding)


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15
Q

A patient on a loop diuretic is noted to have elevated calcium in his urine. Is the loop diuretic responsible?


A

Yes; loop diuretics decrease paracellular Ca2+ reabsorption, leading to increased urinary Ca2+ levels and hypocalcemia


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16
Q

What is the mechanism by which potassium-sparing diuretics cause acidemia?


A

Hyperkalemia leads to potassium entering all cells via the H+/K+ exchanger in exchange for H+ exiting cells


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17
Q

A patient with SIADH is given ADH antagonists for severe hyponatremia. Where do these act, and what do they block from being reabsorbed?


A

ADH antagonists act on the collecting duct, blocking the ADH-mediated reuptake of water


18
Q

In the nephron, a site where only water is reabsorbed (without other electrolytes) is at the ____.


A

Thin descending limb of the loop of Henle


19
Q

By what mechanism involving all cells does potassium loss lead to alkalemia?


A

K+ exits all cells (to maintain a normal serum level) in exchange for H+ entering cells (causing the alkalemia)


20
Q

A man receives loop diuretics for a heart failure flare. How permeable to water is the site where they act? Are electrolytes absorbed there?


A

They act on the thick ascending loop of Henle, which is impermeable to water; yes (Mg2+, Ca2+, and Cl- are absorbed there)


21
Q

A patient begins taking a second diuretic to offset the effect of furosemide. What part of the nephron does this second diuretic act upon?


A

The cortical collecting tubule (this is likely a potassium-sparing diuretic)


22
Q

What is the mechanism of action of loop diuretics?


A

They block Na+/K+/Cl- thick ascending limb cotransporters, abolish medullary hypertonicity, and prevent urine concentration


23
Q

A patient with a sulfa allergy needs urgent loop diuretic diuresis due to heart failure. What medication can you offer him?


A

Ethacrynic acid (it is a phenoxyacetic acid derivative, not a sulfonamide)

24
Q

What are the mechanisms of action of spironolactone and eplerenone? What about triamterene and amiloride?


A

Spironolactone and eplerenone competitively antagonize the aldosterone receptor; triamterene and amiloride block luminal sodium channels


25
Q

A patient starts a thiazide diuretic for hypertension. This acts at the same site as which prominent hormone?


A

Thiazide diuretics act on the distal convoluted tubule, where PTH acts to moderate Ca2+ absorption

26
Q

A patient on a carbonic anhydrase inhibitor develops acidemia. What is the likely cause?


A

Acetazolamide causes the kidney to excrete more HCO3-, decreasing the body’s pH and leading to acidemia


27
Q

Calcium excretion is increased by ____ (loop diuretics/thiazides) and decreased by ____ (loop diuretics/thiazides).


A

Loop diuretics (decreased paracellular reabsorption ); thiazides (enhanced paracellular reabsorption in proximal tubule and loop of Henle)


28
Q

Name some clinical indications for acetazolamide.


A

Glaucoma, urinary alkalinization, metabolic alkalosis, altitude sickness, pseudotumor cerebri

29
Q

A patient with anuria presents with heart failure. Is it safe to give this patient an osmotic diuretic?


A

No (osmotic diuretics such as mannitol are contraindicated in patients with anuria and/or heart failure)

30
Q

What is the effect of the loop diuretic furosemide on calcium handling in the kidney nephron?


A

Furosemide increases calcium excretion (Loops Lose calcium)


31
Q

Potassium and hydrogen secretion occurs at the ____ (cortical/medullary/both cortical and medullary) collecting tubule of the nephron.


A

Both cortical and medullary


32
Q

Name at least two toxicities associated with acetazolamide.


A

Hyperchloremic metabolic acidosis (ACIDazolamide causes ACIDosis), paresthesias, ammonia toxicity, sulfa allergic reactions


33
Q

Name some clinical uses of thiazide diuretics.


A

To treat hypertension, congestive heart failure, idiopathic hypercalciuria, nephrogenic diabetes insipidus


34
Q

Serum levels of which substances are increased as a result of the effects of thiazide diuretics?


A

Glucose (hyperGlycemia), lipids (hyperLipidemia), uric acid (hyperUricemia), and calcium (hyperCalcemia) (hyperGLUC)


35
Q

Both calcium and magnesium are reabsorbed primarily in the renal ____ (cortex/outer medulla/inner medulla).


A

Cortex


36
Q

Name some clinical uses of potassium-sparing diuretics.


A

To treat hyperaldosteronism, potassium depletion, congestive heart failure


37
Q

A patient takes acetazolamide for altitude sickness. What are the main electrolytes absorbed at the site where this drug acts?


A

It acts on the proximal convoluted tubule, where NaCl and NaHCO3-


38
Q

How does a low potassium state lead to alkalemia and a paradoxical aciduria?


A

H+ rather than K+ is exchanged for Na+ at the cortical collecting tubule

39
Q

Ethacrynic acid (a phenoxyacetic acid derivative) is an alternative to ____ for patients who suffer from ____. Name one toxicity.


A

Loop diuretics (furosemide, bumetanide, torsemide); sulfa allergies; hyperuricemia (never use ethacrynic acid to treat gout)


40
Q

Name at least four toxicities associated with using loop diuretics.


A

Ototoxicity, Hypokalemia, Dehydration, Allergy (sulfa), Nephritis (interstitial), Gout (OH DANG!)


41
Q

What acid-base abnormality is associated with thiazide diuretic use?


A

Hypokalemic metabolic alkalosis


42
Q

A patient is noted to have low serum potassium and high levels of potassium in the urine. Could a diuretic be responsible?


A

Yes (all except the potassium-sparing diuretics can cause these findings)


FF Renal (3 decks)

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