Dear Dr. Cannell:
I just saw a patient with Fosamax Jaw. I think I know why it occurs.
It seems that BOTH low Bone Mineral Density (BMD) and vitamin D deficiency are very common in adults with developmental disabilities. I, and others, believe that much (if not most) of the low BMD in these folks represents osteomalacia in addition to osteoporosis. It can be harmful to treat osteomalacia with a bisphosphonate and may lead to fractures of even Fosamax Jaw. Since the DXA machine cannot tell the difference between osteomalacia and osteoporosis, it makes sense to treat for osteomalacia first-especially, if alkaline phosphatase and other bone markers are elevated.
So many of our patients with developmental disabilities are put on bisphosphonates because the DXA reads “osteoporosis,” when they really have osteomalacia. This can lead to hypocalcemia, worsening of seizures, severe muscle weakness and Fosamax Jaw.
The Vitamin D Council could do a real service by getting the word out that just because you have low BMD on DXA, this does not necessarily mean you have osteoporosis—and you had better check for vitamin D deficiency before you start a bisphosphonate-because you might have osteomalacia.
Dr. Steve, Virginia