Glycine
Glycine 1.5% is the most common irrigant solution used; as such, it produces the highest incidence of TURP syndrome.8 This solution is hypoosmotic (osmolality of 200 mosm/kg) compared with the normal serum (osmolality of 280 to 296 mosm/kg).5 In addition, glycine may cause visual disturbances.8 The metabolism of glycine produces ammonia, serine, and oxalate (Figure), and 10% of patients who absorb glycine show a marked hyperammonemia, further exacerbating the neurological effects.9,10
Sorbitol and mannitol
Sorbitol and mannitol irrigation fluids are used less frequently than glycine. Sorbitol 3% is metabolized to fructose and glucose, and has an osmolality of 165 mosm/kg.6 When absorbed systemically, sorbitol’s effects are similar to those of glycine, except that it does not induce visual symptoms. Mannitol 5% solution has the advantage of being isosmotic (275 mosm/kg). It is not metabolized and is excreted entirely in the urine. The excretion of mannitol creates an osmotic diuresis, thereby preventing hyponatremia from occurring.9Sorbitol and Mannitol
What are the treatment options for TURP Syndrome? Can it be prevented?
Patients with TURP syndrome in its mildest form can be asymptomatic, but severe cases can be life threatening or fatal. Unlike the treatment for hyponatremia caused by psychogenic polydipsia or the syndrome of inappropriate antidiuretic hormone, which calls for fluid restriction, plasma volume expansion is indicated in TURP syndrome, as hypovolemia and low-cardiac output develop as soon as irrigation is discontinued.
Hypertonic saline is indicated for neurological symptoms, or if the serum sodium concentration is <120mEq/L.6 Although furosemide has been used to treat acute pulmonary edema, no studies support its routine use in the treatment of fluid absorption,6 and its use may aggravate hyponatremia and hypovolemia.
Bipolar electrosurgical systems, unlike monopolar systems, permit the use of electrolyte solutions such as isotonic saline, thereby significantly reducing the risk of hyponatremia. For hysteroscopic procedures, the American College of Obstetricians and Gynecologists recommends the use of an automated fluid pump and monitoring system, thus minimizing the fluid pressure and halting or terminating the procedure before absorption thresholds are exceeded.11
Case Conclusion
The patient was immediately given a 1 mL/kg bolus of hypertonic saline. Two hours later, her serum sodium improved to 114 mEq/L and serum sodium concentration normalized over the next 24 hours. Her cardiovascular and neurological examinations worsened, however, and she required vasopressors. Her pupils remained fixed and dilated, and she lost her corneal and gag reflexes. A repeat CT of the brain showed persistent cerebral edema with signs of herniation, and she did not recover.
Dr Nguyen is a medical toxicology fellow in the department of emergency medicine at New York University Langone Medical Center. Dr Nelson, editor of “Case Studies in Toxicology,” is a professor in the department of emergency medicine and director of the medical toxicology fellowship program at the New York University School of Medicine and the New York City Poison Control Center. He is also associate editor, toxicology, of the EMERGENCY MEDICINE editorial board.