Low bone density can be due to osteomalacia. Osteomalacia is “soft bones” meaning the amount of bone is normal but it is not mineralized. Therefore in osteomalacia, measurement of “bone mineral density” with a DXA scan will be low. This is due to lack of bone mineral rather than abnormal bone structure. This is in contrast to low bone mass due to osteoporosis where the bone microstructure has deteriorated.
Vitamin D Deficiency
Vitamin D deficiency is a common cause of osteomalacia. With correction of low vitamin D, more calcium is available to provide the needed mineral to make the bone “hard” again. During childhood, osteomalacia is manifest as rickets. The long bones of the legs may bend creating the characteristic bowed legs of rickets.
Low bone density does not equal osteoporosis. The investigation of your low bone density is basically to figure out if this reading is due to osteoporosis or other causes that may manifest as osteomalacia.