Body fluid, electrolytes and diuretics.

The results of a series of studies on body fluid, electrolytes and diuretics are discussed. The findings to date indicate that the sex difference between mean potassium plasma levels in men and women is preserved into old age. Contrary to previous suggestions, there would appear to be no transient self-correcting hypokalaemia associated with illness uncomplicated by potassium-losing therapy, and treatment with potent loop diuretics, provided it is accompanied by potassium supplementation, does not commonly give rise to hypokalaemia even in elderly patients. It has not been possible so far to confirm the relationship between total exchangeable sodium and blood pressure, as previously suggested in elderly patient with essential hypertension. It has been shown that hypokalaemia of a mild degree is associated with an increase in the number of ventricular ectopic beats. It is suggested, therefore, that the conclusion that mild hypokalaemia (between 3.0 and 3.5 mmol/l) is of no significance, at least as far as elderly patients are concerned, may well be untrue.