Risk of osteopenia after proctocolectomy and ileal pouch-anal anastomosis for ulcerative colitis

The aim of our study was to evaluate the influence of pouchitis and villous atrophy on bone mineral density and metabolism at least 5 years after ileal pouch-anal anastomosis for ulcerative colitis (UC).

Eighty-eight subjects with a J-pouch operated on between 1985 and 1994, and 20 ulcerative colitis subjects with a conventional ileostomy were enrolled. Endoscopy was performed and spine and femoral neck bone mineral densities measured. Bone metabolism was assessed by measurement of serum levels of parathyroid hormone, osteocalcin, 25-hydroxyvitamin D3, calcium, alkaline phosphatase and urinary N-telopeptide cross-linked of type I collagen (NTX).

In the lumbar spine, 37% of the J-pouch subjects with subtotal to total villous atrophy had osteopenia (Z score <-1), whereas none of the subjects with normal villous structure had reduced bone densities in the spine or femoral neck. The highest prevalence of osteopenia (66.7%) and the lowest spine (mean -0.89+/-0.36; P = 0.006) and femoral neck (mean -0.63+/-0.29; P = 0.07) Z scores were found among the patients (n = 12) with inflammation in the proximal limb of the pouch. No biochemical parameters were found to predict osteopenia and in stepwise regression analysis, the only independent risk factors for osteopenia were low body mass index and villous atrophy.

Patients with a J-pouch showing high inflammatory activity and villous atrophy in the pouch need long-term follow-up and should be ensured adequate intake of calcium and vitamin D.