[Ostéomalacia following uretero sigmoidostomies (author's transl)].

Surgical anastomosis of the ureter in the sigmoid could lead to osteomalacia. The pathogenesis of this disease is rather complicated and involves several factors, the most important of which is hyerchloremic acidosis associated with modifications of transport across the intestinal lining, and in particular, the elimination of bicarbonates and the reabsorption of H+ ions. This systemic acidosis makes the calcium balance negative by mobilizing calcium bicarbonate from bone and possibly by inhibiting alkaline phosphatase activity. The role of PTH and vitamin D has yet to be satisfactorily explained. The authors present cases of osteomalacia following two uretero-sigmoidostomies, one for bladder exstrophy and the other after bladder removel for tumour. The physiopathological mechanisms of osteomalacia are briefly recalled together with indications of treatment.