Hyperkalemia in patients with
renal failure is frequently treated with a
cation exchange resin (
sodium polystyrene sulfonate, hereafter referred to
as resin) in combination with a
cathartic, but the effect of such
therapy on serum
potassium concentration has not been established. This study evaluates the effect of four single-dose resin-
cathartic regimens and placebo on 5 different test days in six patients with
chronic renal failure. Dietary intake was controlled. Fecal
potassium output and serum
potassium concentration were measured for 12 h.
Phenolphthalein alone caused an average fecal
potassium output of 54 mEq. The addition of resin caused an increase in insoluble
potassium output but a decrease in soluble
potassium output; therefore, there was no significant effect of resin on total
potassium output.
Sorbitol plus resin caused less
potassium output than
phenolphthalein plus resin. On placebo
therapy, the average serum
potassium concentration increased slightly (0.4 mEq/L) during the 12-h experiment. This rise was apparently abrogated by some of the regimens that included resin; this may have been due in part to extracellular volume expansion caused by absorption of
sodium released from resin.
Phenolphthalein regimens were associated with a slight rise in serum
potassium concentrations (similar to placebo); this may have been due to extracellular volume contraction produced by high volume and
sodium-rich
diarrhea and
acidosis secondary to
bicarbonate losses. None of the regimens reduced serum
potassium concentrations, compared with baseline levels. Because single-dose resin-
cathartic therapy produces no or only trivial reductions in serum
potassium concentration, and because this
therapy is unpleasant and occasionally is associated with serious complications, this study questions the wisdom of its use in the management of acute hyperkalemic episodes.