A 50-year-old man has a history of frequent episodes of renal colic with high-calcium renal stones. The most useful diuretic agent in the treatment of recurrent calcium stones is:

Correct Answer: C

Rationale: The correct answer is C) Hydrochlorothiazide. Hydrochlorothiazide is a thiazide diuretic that works by increasing the excretion of calcium in the urine, which helps in reducing the formation of calcium stones in the kidneys. Thiazide diuretics are particularly effective in reducing the risk of recurrent calcium stones due to their mechanism of action in promoting calcium excretion. Option A) Acetazolamide is a carbonic anhydrase inhibitor diuretic that is not typically used for calcium stone prevention. It works in the proximal convoluted tubule and is more commonly used for conditions like glaucoma and altitude sickness. Option B) Furosemide is a loop diuretic that acts on the thick ascending limb of the loop of Henle. While it is effective in treating conditions like edema and hypertension, it is not the first-line choice for preventing calcium stones. Option D) Mannitol is an osmotic diuretic used to reduce intracranial pressure and intraocular pressure. It is not indicated for the prevention of calcium stones. Educational Context: Understanding the different classes of diuretics and their mechanisms of action is crucial in selecting the most appropriate diuretic for specific conditions. In the case of recurrent calcium stones, thiazide diuretics like hydrochlorothiazide are preferred due to their ability to reduce calcium excretion in the urine. This knowledge is essential for healthcare professionals managing patients with renal stone disease and highlights the importance of tailoring treatment to the underlying pathophysiology of the condition.

Correct Answer: C

Rationale: The correct answer is C) Chlorothiazide. Chlorothiazide is a thiazide diuretic known to cause adverse effects on glucose metabolism. Thiazide diuretics can lead to hyperglycemia by reducing insulin sensitivity and impairing glucose tolerance. They can also decrease insulin secretion, leading to elevated blood glucose levels over time. In this case, the patient's elevated fasting and postprandial blood glucose levels after taking an oral diuretic for 6 months suggest diuretic-induced glycemic problems, pointing towards Chlorothiazide as the likely cause. Option A) Acetazolamide is a carbonic anhydrase inhibitor diuretic and is not associated with causing hyperglycemia. Option B) Amiloride is a potassium-sparing diuretic and is also not known to impact glucose levels. Option D) Spironolactone, another potassium-sparing diuretic, does not typically cause hyperglycemia. Educationally, understanding the side effects of commonly prescribed medications is crucial for healthcare providers to make informed decisions and provide optimal patient care. Recognizing the potential adverse effects of diuretics on glucose metabolism can help clinicians monitor and manage patients' conditions more effectively, ensuring better health outcomes.

Correct Answer: B

Rationale: In this scenario, the most likely outcome of adding triamterene to lisinopril for the hypertensive patient would be better blood pressure control, but with a risk of hyperkalemia. The correct answer (B) is based on the pharmacological interactions of these two medications. Lisinopril is an ACE inhibitor that works by dilating blood vessels to lower blood pressure, while triamterene is a potassium-sparing diuretic that helps the body remove excess sodium and water. When combined, triamterene can enhance the antihypertensive effects of lisinopril. However, as a potassium-sparing diuretic, triamterene can lead to hyperkalemia, an elevated level of potassium in the blood, especially when combined with an ACE inhibitor like lisinopril which can also increase potassium levels. Option A is incorrect because adding triamterene should not cause a sudden rise in blood pressure. Option C is incorrect as neither drug directly depresses the heart in a way that would cause cardiac depression. Option D is incorrect as cough is a common side effect of ACE inhibitors like lisinopril, and adding triamterene would not necessarily worsen this side effect. Educationally, understanding the pharmacological mechanisms of different drug classes is crucial for healthcare providers to make informed decisions when managing patients with complex medication regimens. This case highlights the importance of considering potential drug interactions and side effects when combining medications to achieve optimal treatment outcomes for patients with hypertension.

Correct Answer: B

Rationale: The correct answer is B) Caused hypokalemia. Explanation: Hypokalemia, or low potassium levels, can potentiate the toxic effects of digoxin. Digoxin competes with potassium for binding sites on the sodium-potassium pump in cardiac myocytes. Low potassium levels increase the binding of digoxin to these sites, leading to increased intracellular calcium concentrations and enhancing the toxic effects of digoxin on the heart, manifesting as ventricular ectopy and AV nodal block. Why others are wrong: A) Caused hypercalcemia: This is unlikely as hypercalcemia would not enhance digoxin toxicity. C) Caused hyponatremia: While electrolyte imbalances can contribute to digoxin toxicity, hyponatremia is not directly linked to the potentiation of digoxin toxicity like hypokalemia. D) Displaced digoxin from tissue binding sites: This option is incorrect because displacing digoxin from tissue binding sites would not lead to increased toxicity. Educational context: Understanding the interactions between medications like digoxin and diuretics is crucial in clinical practice, especially when managing patients with heart failure. Healthcare providers need to be aware of how electrolyte imbalances, such as hypokalemia induced by diuretics, can influence the effects of medications like digoxin to provide safe and effective care to their patients.