The hyponatremic syndrome is a prevalent phenomenon, according to recent reports, perhaps largely owing to the facility with which sodium determinations have been able to be performed by the flame photometer in the last decade. The low-sodium syndrome or, less specifically, the "low salt syndrome" are terms used synonomously. Related to this syndrome are the former descriptions of "hypochloremic azotemia" and also the syndrome of "water intoxication." 1 The term hyponatremic syndrome implies that there are clinical signs and symptoms which are rather specifically related to a low sodium concentration in the serum and extracellular fluid. In recent years, a low sodium concentration has been found frequently to accompany a wide variety of disease states. This has led to some confusion about the syndrome, since many of the symptoms and signs may be associated with the primary diseases and not necessarily with the incidental finding of low sodium concentration. Thus,