Impaired Bone Growth After Ileal Augmentation Cystoplasty

Abstract

Acid challenged weanling rats that underwent ileal augmentation cystoplasty demonstrated decreased bone mineral density and growth compared to controls. These changes were prevented by bicarbonate replacement.

Skeletal growth and long‐term bone turnover after enterocystoplasty in a chronic rat model

“…Only McDougal et al [28] found a minimal systemic acidosis in their rats, but without providing exact data or even significance levels; their observation that the administration of bicarbonate and ascorbic acid prevents a reduction of calcium content in bone‐ash studies, and decrease of bone density in dual‐photon absorptiometry (DPA), respectively (in an unknown proportion of animals), is usually used to support the assumption that even a minimal disturbance of the acid‐base‐balance may cause bone disease. Similar findings were published by Hochstetler et al [27], who stressed their augmented animals with ammonium chloride to mimic the human condition; when rats with augmentation cystoplasty given 1% ammonium chloride were supplemented with an equal molar diet of sodium bicarbonate, metabolic acidosis resolved and bone mineral density normalized to control values (with an unexplained discrepancy of bone mineral ash content and DEXA). Interestingly, Roth and Gasser [26] found no bone pathology in rats with respiratory compensated acidosis using up‐to‐date technology (DEXA, histomorphometry).…”

“…As the renal capacity to excrete acid loads is many times greater in rats than in man, while maintaining a normal or near‐normal serum pH, urinary diversion alone usually does not create detectable acidosis in these animals [25–27]. Only McDougal et al [28] found a minimal systemic acidosis in their rats, but without providing exact data or even significance levels; their observation that the administration of bicarbonate and ascorbic acid prevents a reduction of calcium content in bone‐ash studies, and decrease of bone density in dual‐photon absorptiometry (DPA), respectively (in an unknown proportion of animals), is usually used to support the assumption that even a minimal disturbance of the acid‐base‐balance may cause bone disease.…”

“…McDougal et al [28] used whole‐body measurements in 30 of originally 78 rats (mortality and selection criteria not given) using DPA; interestingly, DPA was not applied in rats with bicarbonate supplement in the drinking water, the group on which their argument was mainly based. Hochstetler et al [27] were the first to use serial whole‐body measurements ( in vivo , DEXA); although not significantly different at any one time, regression analysis identified significant differences in skeletal mineralization. Roth and Gasser [26] found no differences in BMD (by DPA) when comparing acidotic rats, rats with enterocystoplasty and controls.…”

Changes in bone structure after augmentation cystoplasty in chronic uraemic rats

“…In summary, ileocystoplasty in growing rats with no renal failure compromises bone mineralization predominantly in the cancellous compartment and can diminish the biomechanical properties of bone [8,12–14]. In growing rats with renal failure, ileocystoplasty can aggravate the reduced mineralization caused by uraemia [15] and have profound osteopenic effects on the trabecular architecture of bone, as reported here.…”

“…In previous studies we and others reported that the incorporation of an ileal segment into the bladders of growing rats with normal renal function leads to a reduced gain in bone density [8,12] and compromises the mineralization of the entire skeleton, resulting in osteopenia in the tibia and lumbar spine [13]. The loss of bone mass after ileocystoplasty can be associated with altered biomechanical properties, such as a reduced bone strength of the vertebral body [14].…”