Are potassium supplements for the elderly necessary?

Plasma and total-body potassium (TBK) were measured in 19 elderly patients receiving diuretics and potassium supplements for cardiac failure and in 13 elderly controls. The mean value for the ratio of TBK to fat-free mass (TBK:FFM) was significantly reduced in the patient group. TBK:FFM showed a negative correlation with age but no correlation with plasma potassium or dose of supplements. When controls and patients were matched for sex and age decade, the mean TBK:FFM was decreased significantly in the diuretic group, giving a mean potassium deficit of 13.3%. These results suggest that ageing influences potassium status, and that diuretics and cardiac failure have a greater effect on TBK in old age than in youth or middle age.