A young girl has consumed barium carbonate with suicidal intend She complains of generalized muscle weakness. The most likely electrolyte is-

Oral or inhalation administration of barium carbonate in rats resulted in adverse .... Other symptoms and signs are hypokalemia, cardiac arrhythmias, cardiac .ECG showed flat ST with U waves in 4 patients .and there is hypokalemia Clinical signs include muscle weakness, cramping, fasciculations, paralytic ileus, and when hypokalemia is severe, hypoventilation, and hypotension. ECG changes typically occur when serum potassium is < 3 mEq/L, and include ST segment sagging, T wave depression, and U wave elevation. Ref Harrison 20th edition pg 676