[Clinical application of serum 25OHD].

Serum 25OHD concentration is considered to be an appropriate measure for judging vitamin D insufficiency/sufficiency. It is hard to set its reference value. Nowadays, two reference values, namely 50 nmol/L for prevention of bone fracture and 75 nmol/L for lowering serum PTH concentration have been proposed. In the elderly, if the former value is used for the assessment, almost half of the population will be classified as insufficient, while the latter is used, almost all the population will be classified as insufficient. Precise and reliable measurements for serum 25OHD are critical for the clinical use of the reference value and the reimbursement of serum 25OHD measurement with the national health care system are required in the treatment of osteoporosis.