To the Editor.—
The article by Dr. Berman, "Serum Sodium," (227:1063, 1974) stressed several points necessary to understand and determine the cause of hyponatremia. His classification is yet another effort to simplify this problem and aid the clinician, but some objections must be raised to statements made that are misleading and do not represent the pathophysiology that is responsible.First, the term "dilutional," though apparently accepted, is inappropriate, since nearly all hyponatremia is a dilution, a decrease in the ratio of sodium to water in the plasma. It cannot be a separate category, for it applies to the hyponatremia in inappropriate secretion of antidiuretic hormone and drug-induced hyponatremia as well as that in edematous states. Second, the term "dehydration" is another accepted and misleading misnomer. Dehydration means lack of water, implies nothing about salt balance, and should be reserved for situations truly characterized by a dominant lack of water, diagnosable