What is the best antihypertensive (high blood pressure medication) to use in a patient with nephrolithiasis (kidney stones) when the type of stone is unknown?

From the Guidelines

Thiazide diuretics, particularly hydrochlorothiazide (12.5-25 mg daily) or chlorthalidone (12.5-25 mg daily), are the preferred antihypertensive medications for patients with nephrolithiasis when the stone type is unknown. These medications not only effectively lower blood pressure but also reduce urinary calcium excretion, which is beneficial since calcium stones are the most common type (accounting for about 80% of kidney stones) 1. Thiazides decrease calcium excretion by enhancing calcium reabsorption in the distal tubule of the kidney, thereby reducing the risk of calcium stone formation.

Some key points to consider when managing patients with nephrolithiasis include:

• The use of thiazide diuretics, citrates, and allopurinol has been shown to reduce the risk of recurrent calcium stones 1.
• Combination therapy with these agents was not more beneficial than monotherapy 1.
• The choice of treatment could be based on the type of metabolic abnormality, but evidence from randomized, controlled trials is lacking to correlate the drug of choice and stone type to the prevention of stone recurrence 1.
• Most patients have calcium stones, and evidence showed that thiazide diuretics, citrates, and allopurinol all effectively reduced recurrence of this stone type 1.

If thiazides are contraindicated or not tolerated, calcium channel blockers like nifedipine (30-60 mg daily extended-release) can be considered as they may help reduce stone recurrence while controlling blood pressure. ACE inhibitors and ARBs are generally neutral regarding stone formation but should be used cautiously in patients with uric acid stones as they can affect uric acid handling. Beta-blockers and alpha-blockers have no specific benefits for stone prevention. Regardless of the antihypertensive chosen, adequate hydration (2-3 liters of water daily) remains essential for all stone formers to reduce stone recurrence risk 1.

From the Research

Antihypertensive Medications for Patients with Nephrolithiasis

When managing hypertension in patients with nephrolithiasis, the choice of antihypertensive medication is crucial. The following points highlight the key considerations:

• Thiazide diuretics have been associated with a decreased risk of kidney stone formation in adults aged >65 years, with a hazard ratio (HR) of 0.76 compared to beta-blockers 2.
• Angiotensin-converting enzyme inhibitors (ACEis) and angiotensin receptor blockers (ARBs) have a borderline decreased risk of kidney stone formation, with an HR of 0.90, although this effect is eliminated when considering the risk of requiring an intervention for a kidney stone 2.
• Calcium channel blockers have a comparable risk of kidney stone formation to beta-blockers, with an HR of 1.02 2.

Recommended Antihypertensive Medications

Based on the available evidence, the following antihypertensive medications may be considered for patients with nephrolithiasis:

• Thiazide diuretics, such as indapamide or chlorthalidone, which have been shown to reduce the risk of kidney stone formation 2, 3.
• ACEis or ARBs, which may have a nephroprotective effect and reduce the risk of kidney stone formation, although the evidence is less clear 2, 4.

Dosing Considerations

The dosing of thiazide diuretics is important, with the following doses recommended:

• Indapamide 2.5 mg/d for prevention of stone recurrence 3.
• Chlorthalidone 25 to 50 mg daily for prevention of stone recurrence 3.
• Hydrochlorothiazide (HCTZ) 25 mg twice a day or 50 mg daily for prevention of stone recurrence 3.