Osteomalacia is characterised by impaired mineralisation of bone, usually caused by vitamin D deficiency but can also be secondary to several other rarer conditions.  It is associated with low BMD, as measured by DXA, and fractures.6 Phosphate wasting caused by the use of TDF may be associated with osteomalacia. The clinical presentation is characterised by bone pain and inability to walk due to microfractures.24  Laboratory findings in osteomalacia are dependent on the cause and can include a low serum vitamin D level, hypophosphataemia and an elevated serum alkaline phosphatase level.  As DXA scanning may not differentiate between osteoporosis and osteomalacia, the presence of osteomalacia may not be appreciated.25 Specialist referral is indicated if this condition is suspected.