POTASSIUM SUPPLEMENTS PREVENT SERIOUS HYPOKALEMIA IN COLON CLEANSING

The association between colonic cleansing and hypokalaemia was studied prospectively by monitoring the serum potassium levels in four groups of patients: groups 1 (55 patients), 2 (72 patients), and 3 (97 patie nts) received the same 2-day preparation of 15 g magnesium sulphate an d 10 mg bisacodyl twice daily; group 4 (96 patients) received a 1-day preparation of 2.4 mg sennoside per kg of bodyweight. Groups 1 and 2 w ere on diuretics, but only group 2 received potassium supplementation. Serum potassium levels were measured before and after bowel preparati on. Hypokalaemia was present prior to cleansing in six (11%), and afte r cleansing in 20 (36%) of the 55 patients in the group 1 patients on diuretics but without potassium supplements. There was, after cleansin g, no significant fall in serum potassium in the group 2 patients on d iuretics who received potassium supplements. No hyperkalaemia resulted from supplementation. A significant fall of the mean level of serum p otassium occurred in patients in both group 3 (2-day-preparation) and group 4 (1-day-preparation). We conclude that both 1 day and 2 days of cleansing with cathartics may result in a significant fall in serum p otassium, which can be prevented by oral potassium supplements. Potass ium supplements (three times a day 15 ml of potassium chloride with 0. 9 mmol K per ml during the preparation) in patients on diuretics may b e prudent to avoid the risk of cardiac arrhythmia.