What indicates an adverse effect of sodium polystyrene sulfonate?

Sodium polystyrene sulfonate is a medication primarily used to treat hyperkalemia, or elevated potassium levels in the blood. One of the known adverse effects associated with the use of this drug is the occurrence of diarrhea. This occurs because the medication acts in the intestines to exchange sodium for potassium, which can lead to gastrointestinal disturbances, including osmotic diarrhea.

Diarrhea may be significant because it not only indicates an adverse reaction to the medication but can also contribute to further electrolyte imbalances and dehydration, complicating the therapeutic management of patients who are already dealing with high potassium levels.

While a decrease in serum potassium is actually a therapeutic effect and an increase in serum sodium can also occur due to the sodium absorption during the exchange process, these are not indicators of adverse effects. A decrease in serum calcium is not a typical consequence of sodium polystyrene sulfonate use, so it does not indicate an adverse effect in this context. Therefore, diarrhea stands out as a direct sign of an adverse reaction to the medication.