To the Editor:
We read with interest the article by Rosenberg  on severe hyponatremia after transcervical endoscopic endometrial ablation. He has furthered our knowledge of another possible cause of perioperative hyponatremia.
Although the debate continues regarding the rapidity with which hyponatremia should be corrected, the plasma sodium concentration in the reported cases should not have been increased so quickly (4.8 mmol centered dot L-1 centered dot h (-1) in the first case and 6 mmol centered dot L-1 centered dot h-1 in the second case). Sterns  presented evidence suggesting that demyelinating brain stem lesions seen in patients with hyponatremia resulted from rapid correction of hyponatremia, not from the presence of hyponatremia. In hyponatremic patients with altered mental status or seizures, a reasonable regimen would be to increase the serum sodium concentration "rapidly" (usually with hypertonic saline) at a rate of no more than 1-2 mmol centered dot L-1 centered dot h-1.
Yaacov Gozal, MD
Johanna Schwarzenberger, MD
Department of Anesthesiology, Oregon Health Sciences University, Portland, OR 97201-3098
1. Rosenberg MK. Hyponatremic encephalopathy after rollerball endometrial ablation. Anesth Analg 1995;80:1046-8.
2. Sterns RH. Severe hyponatremia: the case for conservative management. Crit Care Med 1992;20:534-9.