Do you routinely transition patients with recurrent calcium based kidney stones off of hydrochlorothiazide and onto chlorthalidone or indapamide for optimal control of hypercalciuria?

Yes, I do as they are longer acting thiazides and thus have better control over hypercalciuria. I generally start with Indapamide 1.25 mg daily and will titrate up if necessary. I prefer that as opposed to Chlorthalidone as to start with 12.5 mg Chlorthalidone, you need to cut it in half, which is not optimal, though if insurance won't cover the Indapamide, I will go with Chlorthalidone.

Typically, I start with hydrochlorothiazide 25 mg daily (the NoStone Study showed that 12.5 mg per day is equivalent to placebo) and then recheck a 24 hour urine. If calciuria is more than 200 mg/24 hours— the level that separates stone formers from non-stone formers— I either increase hydrochlorothiazide to 25 mg twice daily or switch to chlorthalidone 25 mg daily daily, depending on patient preference and price. I have not used indapamide, although some of my colleagues do and find it safe and effective.

Stephen B. Erickson, MD

I would only exchange a thiazide diuretic drug for therapy in the same category, if there was some reason for doing so, such as insurance coverage or patient preference (once a day medication vs twice daily for maximum benefit). If the drug was ineffective, I don't think that a change in thiazide class drugs is likely to change that circumstance. There are always other dietary approaches that can improve urine risk. For instance, limiting salt and protein intake can reduce calcium excretion.