Metabolic alterations at different levels of renal function following continent urinary diversion through colonic segments.

PURPOSE: We evaluated the influence of renal function on electrolyte and acid-base homeostasis in patients with colonic reservoirs for urine and the ability of these patients to handle an acute acid load.
MATERIALS AND METHODS: The 19 patients studied were divided into 2 groups according to preservation of the glomerular filtration rate at last followup: group 1-well preserved glomerular filtration rate (mean 100 ml. per minute per 1.73 m.2) with an average followup of 8.5 years and group 2-slight to moderate decrease in glomerular filtration rate (mean 55 ml. per minute per 1.73 m.2) with a mean followup of 10.5 years. Renal tubular function was evaluated by urinary levels of protein alpha 1-microglobulin. Baseline serum and urine samples were analyzed for metabolic parameters, and baseline arterial blood gas was measured. Immediately thereafter ammonium chloride loading was performed.
RESULTS: Some difference in acid-base homeostasis was found with slight hyperchloremic metabolic acidosis noted in 4 patients in group 2. Moreover, calcium homeostasis was influenced, with lower levels of ionized calcium noted in group 2. However, no difference was found in the ability of the patients in both groups to handle an acute acid challenge.
CONCLUSIONS: Patients with a glomerular filtration rate of approximately 55 ml. per minute per 1.73 m.2 have sufficient renal function to compensate for the chronic endogenous acid load noted after urinary diversion and they can also handle an acute acid load adequately. Further studies are necessary to evaluate the long-term effects of a chronic endogenous acid load, for example on bone metabolism, in patients with impaired renal function after urinary intestinal diversion.