Hyperkalemia risks in hemodialysed patients consuming fluoride-rich water.

In order to observe the consequences of chronic ingestion of high fluoride-rich water on plasma potassium levels of hemodialysed subjects, we have conducted a retrospective study on 25 patients with chronic renal failure, treated with a substitute method, six of whom (consumers group, group C) were drinkers of a bicarbonate (about 4500 mg/l) and fluoride-rich (9 mg/l) mineral water, the Vichy Saint-Yorre water. With respect to sodium polystyrene sulfonate consumption (n = 17), there was no significant difference between group C and NC (non-consumers group). A significant correlation between plasma fluoride and potassium levels was observed only before dialysis (P < 1 x 10(-7)) but not after dialysis. A group by group analysis revealed that this correlation was linked to group C (P < 5 x 10(-6)), in which kalemia before dialysis was higher than that observed in group NC (P < 0.005). Moreover, it appeared that the higher fluoride levels were, the higher the kalemia was inclined to be. Thus, the risks of hyperkalemia in dialysed patients, who also drink Vichy St-Yorre water or other fluoride-rich waters, are more important, while not forgetting the risk of fluorosis. The mechanisms by which chronically administered fluoride could increase kalemia are also discussed.

Investigation of fluoride elimination during a dialysis session.

We have conducted a study of the elimination kinetics of fluoride ions by a log linear regression analysis of plasma levels obtained during a bicarbonate hemodialysis session, with a dialyzer in polymercaprin for six patients with chronic renal failure. Using plasma fluoride levels of 35 patients studied for 20 months, we have validated these kinetics for hemodialysis with sodium bicarbonate, acetate-free biofiltration, hemodiafiltration with low flow rate and other dialyzers. Our results show that the decrease in plasma fluoride levels is statistically significant only after the first hour, and the fall reaches approximately 30% after a 4 h dialysis session. We propose that post-dialysis measurements of plasma fluoride are now not necessary if levels before dialysis are known.