Does bone resorption inhibition affect the anabolic response to parathyroid hormone?

One of the questions arising from the use of parathyroid hormone (PTH) as an anabolic agent is whether preventing bone loss with inhibitors of bone resorption might result in a greater amount of bone in response to PTH. Two recent independent reports indicate that the anabolic effect of PTH in osteoporotic women appears to be significantly reduced when alendronate is administered in combination with PTH in studies using biochemical markers, quantitative computed tomography and bone mineral density (BMD) measurements. The very different mechanisms of the two treatments reduces the impact of the BMD data, but if the overall conclusion is correct, an effect of PTH on resorption might be necessary for the anabolic effect to follow.