Vitamin B12 metabolism after urinary diversion with a Kock ileal reservoir

To elucidate the influence of construction of a Kock reservoir for urinary diversion using 70 cm of the distal ileum on vitamin B12 metabolism.

Blood samples for determination of cobalamin concentrations were drawn up to 18 years after construction of a Kock reservoir in 97 patients. Preoperative values were obtained in 20 of these patients. Pre- and postoperative Schilling tests and analyses of methylmalonic acid and homocysteine concentrations were performed in subgroups.

The operation did not induce a significant decrease in cobalamin uptake as reflected in the pre- and postoperatively performed Schilling tests. No significant decline in cobalamin concentration postoperatively was noted. The value of analysis of methylmalonic acid and homocysteine concentrations in finding patients with cobalamin deficiency is limited by the fact that kidney function influences the results. Ten per cent of the patients did develop true cobalamin deficiency. A postoperative vitamin B12 value below 200 pmol/l indicates a 50% risk of later cobalamin deficiency.

The construction of a Kock reservoir does not per se cause cobalamin deficiency. Substitution should be instituted at a postoperative concentration below 200 pmol/l.