What distinguishes Bartter from Gitelman syndrome?
Urinary calcium excretion is increased in Bartter syndrome, in contrast with the hypocalciuria found in patients with Gitelman syndrome. Hypomagnesemia is a hallmark findings in Gitelman syndrome and uncommon in Bartter. Another distinguishing feature is the lack of change in urinary chloride in Gitelman patients with thiazide administration.
Interestingly, the Gitelman variant has a relatively high allele frequency of up to 1 in 100 to 400 individuals. Lower blood pressure and increased bone mineral density may be a survival benefit in Gitelman variant carriers. Regardless, both Gitelman and Bartter syndromes have autosomal recessive transmission and are therefore uncommon; when suspected in adults, it is important to exclude surreptitious vomiting and diuretic use.
