Effects of restorative proctocolectomy on renal and adrenal function.

PURPOSE: Restorative proctocolectomy is a standard procedure in the surgical treatment of ulcerative colitis and familial adenomatous polyposis. The radical removal of the colorectum with construction of an ileostomy often results in high stoma losses. These may lead to changes in the electrolyte and acid-base balance and to alterations in renal and suprarenal gland function. METHODS: In this study 33 patients who received an ileoanal pouch before and after proctocolectomy were investigated at different time intervals for electrolyte changes, alteration of the acid-base balance, kidney function, and hormonal changes of the suprarenal glands. Measurements were performed before proctocolectomy, ten days after proctocolectomy with ileal pouch-anal anastomosis under protective loop ileostomy, before ileostomy closure, and 6 to 12 months after ileostomy closure. Neither acute renal failure nor other vital complications were observed. RESULTS: Statistical analysis showed a significant decrease of urine pH to 5.4±0.22 (before ileostomy closure) and metabolic acidosis (pH 7.32±0.04; base excess −1.3±5.6 (before ileostomy closure)). Likewise, we found a decrease in renal clearance to 86 ml/minute (before ileostomy closure) without signs of tubular damage. The most important change during the phase with ileostomy was a functional secondary hyperaldosteronism with aldosterone levels of 63.2±70.8 ng/dl (before ileostomy closure). In comparison with preoperative levels, there was a ten-fold increase in mineralocorticoid adrenal activity. Additionally, during the period with protective ileostomy, the hepatic synthesis of aldosterone-18-glucuronide was only slightly increased, and the cortisol/cortisone ratio was extremely decreased. CONCLUSIONS: These results show that restorative proctocolectomy with ileal pouch-anal anastomosis and protective loop ileostomy significantly influences fluid, electrolyte, and acid-base balance. Functional secondary hyperaldosteronism is of central importance for subsequent renal recompensation. Approximately one-half year after ileostomy closure, the endogenous hormones with mineralocorticoid effects returned to normal levels.