ABSTRACT

Metabolic bone disease following urinary diversion seems to have been first described by Turner,1 who in 1929 reported an 18-year-old boy with generalized rickets developing 10 years after implantation of the ureters into the sigmoid colon because of congenital bladder defect. Turner, however, was unaware of a link between the rickets and the urinary diversion. The possibility of bone complications in patients with urinary diversion was first recognized by Boyd2 when in 1931 he reported a 10-year-old boy who 3 years previously had undergone similar

BOX 8.1 PATHOGENESIS OF OSTEOMALACIA AND RICKETS

Abnormal vitamin D metabolism Vitamin D deficiency

Inadequate dermal production of vitamin D3

Inadequate hepatic synthesis of 25-hydroxyvitamin D3

Defective renal synthesis of 1,25-dihydroxyvitamin D3

Defective end-organ response to l,25-dihydroxyvitamin D3

Renal loss of vitamin D-binding protein

Phosphate deficiency Diminished phosphate intake

Impaired renal tubular absorption of phosphate

Defects in mineralization Enzyme deficiency

Circulating inhibitors of calcification

Abnormal bone collagen or matrix

States of rapid bone formation Miscellaneous

Parenteral alimentation

Gastrectomy

Hyperchloremic metabolic acidosis

ureteric transplantation due to exstrophy of the bladder and 2 years later had developed active rickets as well as chronic acidosis, hypocalcemia, hypophosphatemia and nitrogen retention. The rickets resisted treatment with vitamin D until it was combined with large doses of sodium bicarbonate. Rickets and osteomalacia belong to a group of metabolic bone diseases with varying pathogenesis and characterized by deficient mineralization of osteoid (Box 8.1). Rickets involves widening of the growth plate in the distal ends of long bones, whereas in osteomalacia, mineralization is impaired in the cortical and cancellous bone when growth has ceased (Figure 8.1).