Hyponatremia in 2010---new and noteworthy

St. Louis City Hospital

When patients are hospitalized with hyponatremia, either as the principal problem or an incidental finding, the hospitalist is immediately faced with several questions. Does the patient have acute hyponatremic encephalopathy or not? Should the serum sodium be raised? How much and how fast? What is the best strategy to avoid osmotic myelinolysis?

Several important papers were published this year which may help refine the approach to the evaluation and management of hyponatremia. For acute hyponatremic encephalopathy bolus therapy with 100 ml at a time of 3% saline is gaining popularity and has sound rationale (see here).

The past year saw increased published experience with the use of desmopressin to blunt the rise in serum sodium and decrease the risk of myelinolysis, either reactively in situations of threatened overcorrection or proactively as part of the initial treatment, at least in cases of very severe, e.g. “double digit” hyponatremia.

One paper this year emphasized the special hazard of hyponatremia accompanied by hypokalemia and reminded us that correction of hyponatremia, and possibly even overcorrection, may result merely from efforts at potassium repletion.

Finally, two papers addressed the etiologic diagnosis of hyponatremia, pointing out that clinical volume assessment is difficult and discussing some fine points in the evaluation of serum and urine chemistries.