Citrates in nephrolithiasis: Citrate salts in the treatment of nephrolithiasis part 2

5 Aug
2011

nephrolithiasis part 2

This result is in agreement with Fuselier et al., who ob­served a small, but significant, decrease in urinary calcium ex­cretion during treatment periods. Ali Tekin et al. evaluated, in an open clinical trial, the effects of oral potassium citrate therapy (22 months) in children with calcium stones and hypoc- itraturia; these Authors confirmed that potassium citrate re­duces the recurrence of renal stones and seems to be a safe treatment. These Authors too, found a decrease in urinary cal­cium excretion although it remained within the normal range in most cases, so they concluded that potassium citrate seems to influence, to a low degree, calcium excretion. Moreover, in our paper, basal values of citraturia were lower than follow up values. However, when patients were sub- dived according to urinary citrate excretion, those with the low­est basal citraturia (citraturia lower than 320 mg/24 hours) be­haved differently. In fact after a rise in the first year, urinary cit­rate excretion returned to values similar to or lower than basal value. Also Fuselier et al. observed that in 21% of patients treated with potassium citrate, urinary citrate excretion did not rise. The Authors stated the need for a careful follow-up of the patients treated with potassium citrate in order to identify pa­tients requiring a more aggressive medical therapy and to properly modify the dose of alkali salts. Oxalate, uric acid and creatinine excretion as well as urine vol­ume do not change during the follow up of patients treated with potassium citrate. Moreover potassium citrate does not usually induce an increase in the relative supersaturation ratio of brushite, as it reduces urinary calcium excretion, although an excessive amount of potassium citrate may increase the relative supersaturation ratio of brushite. Furthermore, in patients with distal renal tubular acidosis, potassium citrate treatment appears to improve calcium bal­ance. 1 Internet Online Drugstore cialis professional

In fact it increases intestinal calcium absorption by means of a 1,25(OH)2D3 independent mechanism and reduces urinary calcium excretion. According to some authors, the de­creased calcium excretion can be explained by an increased calcium reabsorption in the distal tubule induced by metabolic alkalosis as well as by the increased luminal pH. The chronic treatment with potassium citrate and other alkaline salts may result in a positive calcium balance. In fact a small but significant increase in bone mineral density in stone form­ing females has been shown. Also Sebastian et al., after treating a group of healthy postmenopausal women with potas­sium bicarbonate, observed an improved calcium balance through an interaction of bone remodelling phases. Several studies in vitro showed that citrate inhibits struvite for­mation. In fact it causes the chelation of magnesium, the dis­ruption of the hydrogen and ionic binding of this mineral and the coating of the surface of struvite crystal. In conclusion alkaline citrate seems to be a rational approach to the treatment of nephrolithiasis in patients with or without hypocitraturia, as it reduces some risk factors involved in stone recurrence. Moreover this form of therapy presents a small number of side effects, mainly gastro-intestinal symptoms (e.g. diarrhea and nausea) and in very few cases hyperkaliemia. About the safety of potassium citrate supplementation there is a general agreement in literature; however Coe et al. report some experimental papers showing that citrate increases in­testinal absorption of some metals such as aluminum and lead. These Authors suggest renal function in patients with re­nal failure should be carefully evaluated to avoid an increased intestinal absorption of aluminum, particularly if they are treat­ed with aluminum antacids. The same precautions may be of some use also in patients with renal stones.

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