We examined the efficacy of potassium-magnesium citrate in preventing recurrent calcium oxalate kidney calculi.
Materials and Methods
We conducted a prospective double-blind study of 64 patients who were randomly assigned to receive placebo or potassium-magnesium citrate (42 mEq. potassium, 21 mEq. magnesium, and 63 mEq. citrate) daily for up to 3 years.
New calculi formed in 63.6% of subjects receiving placebo and in 12.9% of subjects receiving potassium-magnesium citrate. When compared with placebo, the relative risk of treatment failure for potassium-magnesium citrate was 0.16 (95% confidence interval 0.05 to 0.46). potassium-magnesium citrate had a statistically significant effect (relative risk 0.10, 95% confidence interval 0.03 to 0.36) even after adjustment for possible confounders, including age, pretreatment calculous event rate and urinary biochemical abnormalities.
Potassium-magnesium citrate effectively prevents recurrent calcium oxalate stones, and this treatment given for up to 3 years reduces risk of recurrence by 85%.
From among calculus analyses done at Kaiser Permanente Medical Centers in Northern California, we selected all reports of calculi containing at least 50% or more calcium oxalate. After reviewing the medical records, we selected patients who had active, recurrent calculous disease and no secondary cause for nephrolithiasis. All subjects had had 2 or more calculi within the previous 5 years and at least 1 calculus within the previous 2 years. Excluded were subjects who had obstructive uropathy,
Baseline clinical variables were similar for potassium-magnesium citrate and placebo groups (Table 1). Mean urinary biochemical parameters as well as prevalence of defined biochemical parameters and prevalence of defined biochemical abnormalities also did not differ significantly between the 2 groups. Prevalence of multiple urinary metabolic derangements was similar between groups. Among subjects who received placebo 84.8% had 1 or more, 51.5% had 2 or more and 24.2% had 3 or more
We have found that treatment using potassium-magnesium citrate markedly reduces risk of recurrent calcium oxalate nephrolithiasis. In most clinical trials of kidney stone prophylaxis, subjects receiving placebo have a 15 to 20% annual rate of stone recurrence,  a rate somewhat lower than the 27% rate observed in our placebo group. In trials of active drug therapy (thiazide diuretics or potassium citrate) the annual recurrence rate is about 5%, 1, 10 a rate similar to that observed for
Potassium-magnesium citrate can substantially reduce the 3-year recurrence rate of calcium oxalate stone formation. This benefit does not depend on the presence of hypocitraturia, and the drug can therefore be prescribed for calcium oxalate calculus prophylaxis without extensive metabolic testing. Whether substituting magnesium for potassium in the drug formulation provides additional therapeutic effect is unclear because the incremental rise in urinary magnesium excretion is small…
Source: Author links open overlay panelBruce Ettinger, Charles Y.C. Pak, John T. Citron, Carl Thomas, Beverley Adams-Huet, Arline Vangessel