The physiologic basis of the TUR syndrome

To better assess the role of hyperammonemia versus hypoosmolarity versus hyponatremia in the TUR syndrome, we developed a rat model. Sprague-Dawley female rats received an intraperitoneal injection (250 cc/kg body weight) of either 1.5% glycine, 2.0% glycine, 2.0% glycine plus 1.5% mannitol, 3.0% mannitol, 5.0% mannitol, or 2.0% glycine plus 0.25% saline. Arterial blood samples were obtained prior to injection, at 2, 8, 16, and 24 hr and analyzed for osmolarity, sodium, and ammonia. Those animals receiving 2.0% glycine, 2.0% glycine plus 1.5% mannitol, and 5.0% mannitol all died within 24 hr with lethargy, convulsions, and coma. Hyponatremia developed in all animals; death, however, occurred only when the sodium concentration declined to 90-95 meq/dl. Mannitol maintained serum osmolarity but did not prevent coma and death. Including 0.25% saline in the initial injection, or an iv injection of 5.0% saline delayed 8 hr achieved 100% survival. Ammonia concentrations increased 15-fold by 8 hr in groups receiving 2.0% glycine; it rapidly decreased to near normal by 24 hr. Decreasing the rise in ammonia by 50% with iv arginine had no effect on survival. Our results suggest that hyponatremia rather than hyperammonemia or hypoosmolarity accounts for the major morbidity and mortality secondary to the TUR syndrome.