37 Questions
What is the primary site of action for loop diuretics?
Thick ascending limb of the loop of Henle
What is the consequence of loop diuretic treatment on calcium and magnesium reabsorption?
Inhibition of calcium and magnesium reabsorption
What is the clinical consequence of increased downstream delivery of sodium in loop diuretic treatment?
Metabolic alkalosis
Which electrolyte imbalance can loop diuretic treatment predispose to, especially in the setting of cardiac insufficiency?
Hypokalemia
Which drugs are the drugs of choice to treat Liddle’s syndrome?
Amiloride and triamterene
How does amiloride affect the impairment of urinary concentrating ability caused by lithium?
Attenuates or prevents it
Which diuretics are used clinically to treat hypokalemic alkalosis secondary to mineralocorticoid excess?
Spironolactone and eplerenone
What is the diuretic action of spironolactone or eplerenone aimed at minimizing?
The risk of cardiovascular compromise from excessively rapid or extensive diuresis
What is the role of mineralocorticoid receptor antagonists in the treatment of ascites and edema associated with impaired plasma protein biosynthesis?
They are the diuretics of choice
What have studies suggested about the effect of mineralocorticoid receptor antagonists in the setting of coronary ischemia?
They preserve cardiac function
What effect do spironolactone and eplerenone have on mortality in patients with heart failure?
They reduce mortality
What is the cause of Liddle’s syndrome?
Gain-of-function mutations in β- or γ-subunits of the ENaC Na+ channel
What is the effect of amiloride on the reabsorption of lithium by ENaC?
It is reabsorbed in an amiloride-sensitive manner
Which diuretic is approximately 40 times more potent than other loop diuretics?
Bumetanide
What is a key consideration when using loop diuretics?
They should not be co-administered with aminoglycosides
Which condition are loop diuretics first-line therapy for?
Acute relief of pulmonary and peripheral edema in heart failure
What is a potential use of loop diuretics?
Treating hyperkalemia
Where do thiazide diuretics primarily inhibit sodium chloride reabsorption?
Distal convoluted tubule
What effect do thiazide diuretics have on glucose tolerance?
They decrease glucose tolerance
What is a potential use of thiazide diuretics?
Managing osteoporosis
What is a key consideration when using thiazide diuretics for hypertension?
They should not be administered concurrently with antiarrhythmic agents that prolong the QT interval
What is a potential effect of thiazide diuretics on calcium reabsorption?
They promote increased calcium reabsorption
Which diuretic is a first-line agent for hypertension?
Hydrochlorothiazide
What is a potential benefit of thiazide diuretics shown in clinical trials?
Reducing cardiovascular-related mortality
What is a potential adverse effect of loop diuretics on calcium diuresis?
They promote increased calcium diuresis
Which diuretic can be taken once a day, unlike hydrochlorothiazide?
Chlorthalidone
What is the basis for most clinical trials documenting beneficial effects of thiazide diuretics for hypertension treatment?
Chlorthalidone
Which diuretic can modestly decrease urine flow in nephrogenic diabetes insipidus?
Thiazides
What can be used to treat nephrogenic diabetes insipidus associated with chronic lithium therapy, instead of thiazides?
Amiloride and acetazolamide
What do potassium-sparing diuretics do in terms of potassium reabsorption in the nephron?
Increase nephron reabsorption of potassium
What do spironolactone and eplerenone inhibit to counteract aldosterone action?
Nuclear translocation of the mineralocorticoid receptor
What percentage of essential hypertension patients have elevated aldosterone levels?
Up to 20%
What do amiloride and triamterene competitively inhibit to treat hypertension?
ENaC Na+ channel
What can potassium-sparing diuretics cause in terms of potassium and metabolic acidosis?
Hyperkalemia and metabolic acidosis
What effects can potassium-sparing diuretics potentiate?
Effects of more proximally acting diuretics
What does aldosterone regulate in collecting duct principal cells?
Sodium channel expression
Which diuretic is used to treat central diabetes insipidus?
Desmopressin
Study Notes
Diuretics and Their Mechanisms of Action
- Thiazide diuretics can cause hypokalemic metabolic alkalosis due to increased K+ and H+ secretion from increased Na+ presentation to the collecting duct
- Hydrochlorothiazide should be taken several times a day, while chlorthalidone, a longer-acting thiazide, can be taken once a day
- Chlorthalidone was the basis for most clinical trials documenting beneficial effects of thiazide diuretics for hypertension treatment
- Patients with diabetes insipidus can be treated with desmopressin for central diabetes insipidus, while thiazides can modestly decrease urine flow in nephrogenic diabetes insipidus
- For nephrogenic diabetes insipidus associated with chronic lithium therapy, thiazides may be supplanted by amiloride and acetazolamide
- Potassium-sparing diuretics increase nephron reabsorption of potassium by interrupting Na+ reabsorption in the collecting duct
- Aldosterone regulates sodium channel expression in collecting duct principal cells
- Spironolactone and eplerenone inhibit aldosterone action by preventing nuclear translocation of the mineralocorticoid receptor
- Up to 20% of essential hypertension patients have elevated aldosterone levels, and mineralocorticoid receptor antagonists are used to treat hypertension
- Amiloride and triamterene are competitive inhibitors of the ENaC Na+ channel and are used to treat hypertension
- Potassium-sparing diuretics can cause hyperkalemia and metabolic acidosis due to decreased Na+ uptake and decreased H+ secretion
- Potassium-sparing diuretics can potentiate the effects of more proximally acting diuretics, including loop diuretics, and are occasionally used to counteract the potassium-wasting effects of thiazides
Learn about the mechanisms of action and clinical use of diuretics in this informative quiz. Explore topics such as thiazide diuretics, potassium-sparing diuretics, and their impact on electrolyte balance, hypertension treatment, and diabetes insipidus management.
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