Peritoneal fluid urea nitrogen and creatinine reference values

Abstract

Objective: To evaluate urea nitrogen and creatinine levels in peritoneal fluid. Methods: We prospectively evaluated 20 consecutive women having radical hysterectomy with lymphadenectomy. On postoperative days 2 and 3, serum, urine, and peritoneal fluid samples were tested for urea nitrogen and creatinine. Using power analysis we calculated an adequate sample size to be 16 patients. Results: The mean urea nitrogen was 11 mg/dL in serum, 11 mg/dL in peritoneal fluid, and 469 mg/dL in urine. The mean creatinine was .9 mg/dL in serum, 1.0 mg/dL in peritoneal fluid, and 141 mg/dL in urine. Urea nitrogen and creatinine values in peritoneal fluid and serum were essentially identical. Urine urea nitrogen and creatinine values were significantly greater than serum and peritoneal values (47 to 157 times greater) ( P < .011). On postoperative days 2 and 3, serial levels of serum, peritoneal fluid, and urine urea nitrogen and creatinine in the same subject showed no significant variation ( P ranging from .19 to .31). Conclusion: Normal reference values of urea nitrogen and creatinine in peritoneal fluid are equivalent to serum values and significantly less than urine levels.