Atlanta-When life gives you lemons-or in this case, hypocitraturic nephrolithiasis-make lemonade.
That's the conclusion reached by a group of researchers from the Duke University Medical Center, Durham, NC, who found that mildly hypocitraturic patients who are unable to tolerate potassium citrate experienced significant increases in urinary citrate levels and decreases in stone formation rate when they regularly ingested a mixture of water and reconstituted lemon juice.
In fact, there is only one other published study on the subject. It came a decade ago from a group led by Marshall Stoller, MD, at the University of California, San Francisco (J Urol 1996; 156:907).
"In many ways, we weren't surprised by our results, given the previous short-term study conducted by Dr. Stoller and his group at UCSF," Kang said at the AUA annual meeting here. "One of the most significant findings of the current study that we did not necessarily anticipate was the fact that none of the patients on lemonade therapy had progression of stone disease requiring surgical intervention over a treatment period of 3.5 years.
"It's nice to see a citraturic response in patients, but most importantly, you want them to stop forming stones."
Increased citrate levels
The Duke study compared 12 patients on lemonade therapy with an age-and sex-matched control group of patients treated with potassium citrate. The "lemonade" was actually 120 mL of reconstituted lemon juice mixed with two liters of water and consumed throughout each day.
"Therefore," said Kang, "a known and consistent amount of citric acid [5.9 grams] was delivered daily. We encouraged patients to sweeten the mixture to taste with artificial sweetener to avoid unnecessary intake of sugar."
The investigators analyzed and compared pre-and post-therapy 24-hour urine parameters for both groups. New stone formation was assessed via spontaneous passage, surgical removal, appearance of new stones, or increase in size of existing stones on x-ray.
After a mean treatment duration of almost 42 months, 11 of 12 patients receiving the lemonade therapy demonstrated increased urinary citrate levels during therapy (a mean increase of 354 mg, p<.005). That compared with a mean increase of 472 mg among the 15 patients in the potassium citrate group (p<.0001).
There were nonsignificant increases in mean urinary volume, pH, calcium, sodium, and uric acid, and a nonsignificant decrease in urinary oxalate among patients regularly drinking the lemonade mixture.
Lemonade therapy patients also showed a decreased stone burden, from 37.2 mm2 to 30.4 mm2. Their mean stone formation rate fell from one stone/patient/year before treatment to 0.13 after.
"We strongly believe that future prospective studies are required to ultimately determine lemonade therapy's role, but this initial long-term retrospective study is quite encouraging," said Kang, who added that his group has discussed the possibility of initiating a large, multicenter, prospective trial to evaluate the beneficial effects of lemonade therapy.