Signs and symptoms of electrolyte disorders.

A genuine understanding of the functions of sodium, potassium, calcium , magnesium and their salts in the organism would necessitate a comprehension of the nature of protoplasm and its behaviour in living cells, something we have not begun to attain. Since Peters and Van Slyke published their classic text there has been an enormous increase in understanding of the processes governing the transport of ions across cell membranes. It is chastening, nevertheless, to reflect that the major clinical manifestations of electrolyte disorders observed at the bedside by history, physical examination, and bedside laboratory apparatus were known well to clinicians 40 and more years ago. For the most part, disturbances of the distribution and concentration of body electrolytes affect cellular function rather than structure. Exceptions to this rule are seen in the nephropathy and myocarditis of severe potassium deficiency and in the well-marked lesions of calcium intoxication, but the predominant effect of alterations in electrolyte concentration are likely to be detected in their influence on chemical and electrical gradients across cell membranes. Hence the symptomatology of electrolyte disorders has much to do with changes in the behavior of excitable tissues. Neurological disturbances are prominent, as are changes in cardiovascular function and in skeletal muscle. Most important of all from the standpoint of the clinician is that most of the symptoms described in this review are reversible with proper therapy. HYPERNATREMIA The sense of thirst is so strong a defender of the serum sodium in normal individuals that hypernatremia is never encountered unless thirst is impaired or rendered ineffective because the patient is comatose or is denied access to water. Even in patients with diabetes insipidus in whom water losses may amount to gallons per day, the intake of water usually keeps pace with its excretion. Serum sodium is elevated minimally or not at all as long as the patient is awake and able to drink. When thirst is no longer permitted to operate, however, the serum sodium rises. Hypernatremia is especially