The efficacy of acute administration of pamidronate on the conservation of bone mass following severe burn injury in children: a double-blind, randomized, controlled study

Abstract

Bone loss is a known complication of severe burn injury. It is, in part, due to increased endogenous glucocorticoids that contribute to the reduction in bone formation and osteoblast differentiation, hypercalciuria secondary to hypoparathyroidism, and vitamin D deficiency. In this study we attempted to prevent post-burn bone loss by acute intravenous administration of the bisphosphonate pamidronate. We enrolled 43 children, with burns of >40% total body surface area, in a randomized, double-blind, placebo-controlled study, administering the study drug within 10 days of burn injury and again 1 week later. Dual energy X-ray absorptiometry was performed prior to drug therapy, at hospital discharge and at 6 months post-burn. Urine specimens were obtained at baseline and discharge for determination of calcium and free deoxypyridinoline. Blood was obtained along with the urine specimens for measurement of intact parathyroid hormone (iPTH) and ionized calcium (Ca) levels. Following doxycycline labeling, intra-operative iliac crest bone biopsies were obtained, and bone histomorphometry was determined. At time of discharge there were no differences in total body bone mineral content (BMC), but lumbar spine BMC was significantly higher in the pamidronate group (P<0.005). By 6 months post-burn the differences in lumbar spine BMC persisted, but, now, total body BMC was significantly higher in the pamidronate group (P<0.05). Bone histomorphometry and levels of urine Ca and free deoxypyridinoline failed to show significant increases in bone formation or decreases in bone resorption. Pamidronate did not exacerbate the hypocalcemia in burn patients. In summary, acute intravenous pamidronate administration following burns may help to preserve bone mass, perhaps by inhibiting the glucocorticoid-induced apoptosis of osteoblasts and osteocytes.