In Reply.—Bartter's syndrome is indeed an intriguing disease to study and we welcome comments such as those of Dr Sann. We found some of his comments confusing. The only similarity between our two articles was that both suggest that some patients with Bartter's syndrome are sodium losers whereas others are not, a fact we documented with ten references in our article. Otherwise, we attempted to separate these two groups (salt losers and non-salt losers) based on biochemical (plasma sodium, potassium, chloride, magnesium, calcium, and bicarbonate levels, renin activity, and blood pH) and historical (age, tetany, and episodes of volume depletion) differences, whereas the article by Sann et al separates the two on the basis of an angiotensin II infusion. Also, we have not found any reference to hypomagnesemia in the communication by Sann et al and assume that their comment on this subject has not yet been published.