Urinary pH and excretion of gentamicin.

makes multiple tracer studies more complicated." In reply to their query the method used to measure the loss of potassium from the dialysate, which was 150 mEq in my series', was a direct measurement. The statement by them that: "there is a wide range of potassium status in patients with chronic renal failure being maintained with haemodialysis" contradicts their next statement that: "The absence of a positive relation between the duration of regular dialysis treatment and the total body potassium, together with the balance studies in two patients, indicates that twice-weekly dialysis against a dialysate potassium content of 1 mEq/l. is compatible with the maintenance of potassium balance." This conclusion is reached from two patients only. Finally, I would like to reiterate a statement in my paper' that "a level of 1 mEq/ litre in the dialysate fluid may be too low" for use in prolonged haemodialysis and suggest that this level should be adjusted according to various factors such as dietary intake of potassium; variation in potassium states found among non-dialysed patients with chronic renal failure as suggested by Boddy et al.; duration of prolonged haemodialysis; and the type of dialyser and the number of hours necessary for patients to be dialysed per week.-I am, etc.,