Clinical features and management of poisoning due to potassium chloride

Potassium is one of the most abundant ions in the human body and yet it is difficult to assess potassium balance. Potassium chloride is extensively used as a potassium supplement, both by physicians as a therapeutic modality and by the general public, mostly in the form of salt substitute. Therapeutically, both the oral and intravenous forms of potassium are utilised. Overdose of potassium is not as frequently encountered in clinical practice as hyperkalaemia (excess potassium in the body) due to acute or chronic renal disease. Potassium homeostasis is maintained very delicately and is governed by the daily consumption of potassium and the renal excretion mechanisms. Any change in these or related factors can present as hyperkalaemia. However, potassium overdoses leading to serious consequences do occur. Orally, the dose of potassium has to be large enough so that the normal excretory mechanisms for potassium are overcome and clinical toxicity occurs. It takes a much bigger dose of ingested potassium to produce toxicity in a person with normal renal function than in patients with compromised renal function. Potassium toxicity manifests in significant, characteristic, acute cardiovascular changes with ECG abnormalities. Besides cardiovascular effects, neuromuscular manifestations in the form of general muscular weakness and ascending paralysis occur. Gastrointestinal symptoms manifest as nausea, vomiting, paralytic ileus, and local mucosal necrosis which may lead to perforation. It is imperative when treating hyperkalaemia that the whole clinical picture is taken into account rather than the numerical potassium values. Only the extracellular potassium can be measured in the laboratory, yet 98% of the body potassium is intracellular and cannot be measured. In acute overdose situations due to ingestion of potassium salt, the general principles of treatment for overdoses should be followed. Calcium chloride infusion, dextrose and Insulin in water, and correction of acidosis with sodium bicarbonate are helpful in controlling the acute, life-threatening cardiac arrhythmias. These modalities do not remove the excess potassium from the body. That is achieved either by utilising ion-exchange resins or by mechanically removing potassium via haemodialysis. To curtail inadvertent or accidental potassium overdoses, physicians should prescribe any potassium supplements very carefully to their patients and monitor the plasma potassium periodically.