[5][6] Pendrin was initially identified as a sodium-independent chloride-iodide exchanger[7] with subsequent studies showing that it also accepts formate and bicarbonate as substrates.

Pendrin is the protein which is mutated in Pendred syndrome, which is an autosomal recessive disorder characterized by sensorineural hearing loss, goiter and a partial organification problem detectable by a positive perchlorate test.

By phylogenetic analysis, pendrin has been found to be a close relative of prestin present on the hair cells or organ of corti in the inner ear.

[15] Pendrin is also expressed in the kidney, and has been localized to the apical membrane of a population of intercalated cells in the cortical collecting duct where it is involved in bicarbonate secretion.

Only under extreme situations of salt depletion or metabolic alkalosis, or with inactivation of the sodium-chloride cotransporter, are fluid and electrolyte disorders manifested in these patients.