We recommend to maintain 25(OH)D levels above 30 ng/mL (75 nmol/L) in subjects: With osteopenia, osteoporosis or fragility fractures; On treatment for osteoporosis; Who belong to at risk categories (see Section 3.1). We suggest to consider serum PTH measurement when vitamin D values are lower than 30 ng/mL (75 nmol/L), particularly if tested in Summer and Autumn.