CHANGES IN CALCIUM METABOLISM AND BONE DEMINERALIZATION AFTER ORTHOTOPIC INTESTINAL NEOBLADDER CREATION:

Skeletal health after intestinal bladder augmentation: findings in 54 patients

OBJECTIVE

To evaluate the risk of osteopenia in patients after intestinal bladder augmentation.

PATIENTS AND METHODS

In all, 54 patients with bladder augmentation were evaluated during the regular follow-up programme. Augmentation was performed because of paediatric neurogenic or non-neurogenic reasons. Areal bone mineral densities (aBMD) for the lumbar spine (L1-L4), femoral neck and whole body were measured with dual-energy X-ray absorptiometry. In addition, acid-base balance and plasma 25-hydroxyvitamin D (vitamin D), kidney and gonadal functions as well as body mass index (BMI) were measured. Findings were correlated with clinical characteristics.

RESULTS

BMD was reduced in 34 (63%) of the 54 patients. There was a significant difference in the prevalence of decreased aBMDs between neurogenic and non-neurogenic groups 31 of 42 patients (74%) and three of 12 patients, respectively (P < 0.01). There were spinal compression fractures in 23% of patients. Risk factors for osteoporosis were inability to walk, renal insufficiency, hypogonadism, vitamin D deficiency, acidosis, and a low BMI. There was moderate or severe vitamin D deficiency in 42% of patients but the vitamin D status did not correlate with BMD. The glomerular filtration rate correlated to the whole-body aBMD (P = 0.04). In 26% of patients (predominantly males with myelomeningocele) plasma follicle-stimulating hormone levels were elevated, indicating variable degrees of hypogonadism. Hypogonadism was associated with reduced lumbar spine aBMD (P = 0.03).

CONCLUSION

Patients with paediatric reasons for bladder augmentation are at risk of osteopenia and compression fractures. The risk factors are mostly related to the patient's underlying illness and not to the augmentation per se.

Significance of renal function in changes in acid-base metabolism after orthotopic bladder replacement: colon neobladder compared with ileal neobladder

BACKGROUND

The objective of this study was to determine whether renal function influences the acid-base metabolism in patients undergoing orthotopic bladder replacement using intestinal segment.

METHODS

Acid-base balance, serum electrolytes and renal function were studied in 30 patients with colon neobladder and 18 patients with ileal neobladder. Mean follow up was 51 months. Effects of renal function on acid-base metabolism in both types of bladder replacement were compared. Therapeutic efficacy of the sodium bicarbonate administration was also evaluated in cases with hyperchloremic acidosis.

RESULTS

No significant differences were observed in any of the variables examined between the colon and ileal neobladder groups, except for potassium concentration. Although metabolic acidosis was detected using the Siggard-Anderson acid-base nomogram in eight (26.7%) and seven (38.9%) patients in the colon and ileal neobladder groups, respectively, this difference was not significant. In both the colon and ileal neobladder groups, the serum creatinine concentrations in patients diagnosed with metabolic acidosis were significantly higher than in those diagnosed with a normal metabolic status. Furthermore, as a result of severe metabolic acidosis, three (10.0%) and three (16.7%) patients in the colon and ileal neobladder groups, respectively, were administered sodium bicarbonate and their metabolic status was fully normalized.

CONCLUSIONS

Despite there being no statistical difference, patients with ileal neobladder may more easily develop metabolic acidosis compared with those with colon neobladder. In addition, a close association between the serum creatinine level and the degree of metabolic acidosis was observed in both groups. However, even if severe metabolic acidosis occurs, it is relatively easy to correct using sodium bicarbonate. These findings suggest that it might be safe to use a colon segment for orthotopic bladder reconstruction in patients with higher serum creatinine levels, despite no significant difference in acid-base metabolism and detection rates of metabolic acidosis between the colon and ileal neobladder groups.