Vitamin B12 deficiency in patients with urinary intestinal diversion

Metabolic complications of urinary intestinal diversion

Patients with a urinary bladder malignancy or severe anatomical/functional bladder abnormalities may be candidates for urinary diversion at the time of cystectomy. Most urinary diversions are constructed from intestinal segments. Urological surgeons who perform urinary diversion surgery should be aware of the physiological and metabolic changes that can occur when intestinal segments are in direct contact with urine. The complications associated with urinary diversion are both acute and chronic. The most important factor associated with the development of metabolic complications following urinary diversion is the length of time that the urine is in contact with the bowel and the type of bowel segment used for urinary diversion. In this review, we describe the metabolic complications associated with urinary diversion, their characteristic clinical presentation, follow-up, and specific treatment.

Metabolic Evaluation of 94 Patients 5 to 16 Years After Ileocecal Pouch (Mainz Pouch 1) Continent Urinary Diversion

PURPOSE In continent urinary diversion metabolic disturbances may be encountered in long-term followup. We evaluated metabolic consequences in patients with a minimum followup of 5 years after Mainz pouch 1 urinary diversion.

MATERIALS AND METHODS

At our institution continent urinary diversion using the ileocecal segment was performed between 1983 and 1995 in 458 patients. A total of 94 patients with an ileocecal pouch for a minimum of 5 years were reevaluated for metabolic changes. Median followup was 9.0 years. Routine laboratory parameters, blood gas analysis, vitamin B12, vitamin D25, cross-laps, bone specific alkaline phosphatase, osteocalcin and propeptide of type I collagen were obtained. Bone density was measured in 18 patients. Vitamin B12 changes could be followed longitudinally in 24 patients.

RESULTS

Medians of all parameters were in normal ranges. Clinical examinations revealed no signs of megaloblastic anemia, funicular myelosis or osteoporosis. There was no significant decrease of vitamin B12 in the long run. After followup examination we recommended vitamin B12 supplementation in 32% of patients because levels were in the lower normal range or below. A total of 37% of patients continue to take Na+/K+-citrate for prevention of metabolic acidosis.

CONCLUSIONS

Patients with an ileocecal pouch and a followup of more than 5 years did not present with clinical symptoms caused by metabolic disturbances. Nevertheless, systematic followup of blood gases in particular and alkali supplementation may have prevented bone demineralization. Followup of vitamin B12 is of concern because about a third of these patients need supplementation.

Intermediate effects of the ileocaecal urinary reservoir (Charleston pouch 1) on serum vitamin B12 concentrations: can vitamin B12 deficiency be prevented?

OBJECTIVE

To assess the long-term effects of a form of ileocolic urinary reservoir (Charleston Pouch 1) on vitamin B12 serum levels, as vitamin B12 deficiency may be an important long-term risk after urinary diversion by this method.

PATIENTS AND METHODS

The study included 60 patients (mean age 52 years, range 27-77; 33 men and 27 women) who had a follow-up of >or= 36 months (36-132 months) after the construction of an ileocaecal urinary reservoir. Vitamin B12 serum levels were determined at the time of diversion and again when the patients were evaluated every 6 months.

RESULTS

Fifty-eight patients had a normal serum vitamin B12 concentration before surgery (two patients were excluded from the study because they had low levels); the mean level was 464 pg/mL (normal range 247-1000). At 6 and 12 months, the mean vitamin B12 levels were 367.5 and 468.5 pg/mL; at 1.5, 2, 3, 4, 5, 6, 7, 8, 10 and 11 years, the mean levels were 305, 495.5, 436.5, 379.5, 423.5, 393, 529.5, 631, 333.5 and 340 pg/mL, respectively.

CONCLUSION

Ileocaecal urinary reservoirs have no adverse effects on serum vitamin B12 levels for up to 10 years after surgery. Patients with vitamin B12 deficiency must be identified and given adequate parenteral doses for life. Because body stores of vitamin B12 may not be depleted for many years, problems with B12 may be masked for a long time. We recommend that vitamin B12 levels be obtained annually, that a modest supplement twice yearly (by injection) may be beneficial and that serum vitamin B12 must be sampled before giving vitamin B12 injections, to avoid false results.

Vitamin B12 malabsorption following bladder reconstruction or diversion with bowel segments

BACKGROUND

Vitamin B12 is absorbed exclusively in the terminal ileum the resection of which may produce malabsorption of B12. The present study aimed to determine whether the length or specific segment of the intestine used in bladder reconstruction affects the overall incidence of B12 malabsorption. It was also aimed at the reasonable way of following these patients.

METHODS

Seventy patients who underwent urinary reconstruction between 1988 and 1997 were studied: 28 had undergone orthotopic reconstruction, 14 had ileal conduit diversion, 8 had continent diversion and 20 had undergone enterocystoplasty. The median follow up was 65 months (10-137 months). Indications for operation included carcinoma of the bladder, neurogenic bladder dysfunction, idiopathic detrusor instability and interstitial cystitis. Schilling tests were performed, and serum B12 level and haematological indices were measured.

RESULTS

Patients were classified depending on whether the ileocaecal junction was used. Group 1 included ileal conduit and entero-cystoplasty where 15-20 cm of ileum, 15-20 cm from ileocaecal junction was used. Group 2 consisted of orthotopic reconstruction and continent diversions where the ileocaecal segment was used. Group 3 comprised patients in whom long ileal segments (50-60 cm) had been used for reconstruction. Five patients in group 1 and one in group 2 had low B12 levels, but none had developed neuropathy or megaloblastic anaemia. One patient in group 1, and six patients in group 2 had low Schilling tests indicating intestinal malabsorption of B12. No patient in group 3 had a low B12 or an abnormal Schilling test.

CONCLUSION

This study showed that use of ileocaecal segments results in intestinal malabsorption of B12. The length of ileum alone does not seem to be the determinant factor in causing B12 deficiency or B12 malabsorption.

Vitamin B12 and folate after 5-12 years of continent ileal urostomy (Kock reservoir) in children and adolescents

OBJECTIVE

To assess B12 and folate deficiency after continent urinary diversion via a Kock continent urinary reservoir in children and adolescents.

METHODS

Ten boys and 10 girls (10.8-18 years old at surgery) were operated with a Kock reservoir and followed for 5-12 years (mean 8.5). The follow-up period was divided into early (3 months-5 years, EFU) and late (5-12 years, LFU) follow-up. Patients were investigated for haemoglobin, serum iron, total iron binding capacity (TIBC), serum Vitamin B12, serum and blood folate, methylmalonic acid (MMA), homocystine and glomerular filtration rate.

RESULTS

Two patients developed subnormal B12 values (median 107.5 pmol/l), one at the EFU, and the other at LFW. The B12 value decreased during the LFU compared to the EFU in nine patients, but it was still within the normal range. Two patients with renal impairment had elevated MMA with normal B12 values. Five patients had high values of homocystine with folate deficiency and/or B12 deficiency and renal impairment. Plasma folate mean value was normal during the whole follow-up. Blood folate was below normal in five patients at the EFU. Two of these five patients, in addition to three patients, had low values at the LFU. Three of four patients with remaining short terminal ileum (20-45 cm) had normal B12 values at both the EFU & LFU and one had low values at the LFU. Six patients had subnormal GFR at the LFU.

CONCLUSIONS

To a similar degree as in adults, Vitamin B12, folate and iron deficiency can occur in children and adolescents after continent urinary diversion using an ileal segment. Therefore, Vitamin B12 and folate should be monitored regularly in these patients. Serum MMA and homocystine may offer increased detection of Vitamin B12 deficiency, especially in the patients with normal renal function. Vitamin B12 deficiency is neither correlated with the time elapsed since surgery, nor with the ileum length. Patients are usually asymptomatic, so patients with true B12 deficiency should be identified and placed on life-long Vitamin B12 therapy. An adequate synthetic folic acid as supplements or fortified food is recommended for patients with folate deficiency.