[Systematic diagnostic workup: differential diagnosis of various forms of osteoporosis].

The objects of a rational approach to the diagnosis of osteoporosis are the identification of patients with osteopenia/osteoporosis by radiological methods, investigations concerning the etiology of the disease and an assessment of bone turnover by biochemical markers. Current classifications of osteoporosis are explained. The WHO classification of osteoporosis and a clinical classification according to severity are based on bone densitometry and fractures. In accordance with pathogenetic aspects a division in osteoporosis without or with known causes is possible (primary/secondary), moreover several regional forms of osteoporosis are mentioned. A classification in "low-" or "high-turnover" osteoporosis is possible by an assessment of the rate of bone loss. The diagnostic procedures in osteoporosis include the patients' history (pain, skeleton, risk factors for osteoporosis and for falls) and an exact physical examination. Essential radiological investigations are radiographs of thoracic and lumbar spine and a bone mass measurement (dual X-ray absorptiometry--DXA or quantitative computerized tomography--QCT, possibly also a quantitative ultrasonography). Basic laboratory tests, including markers of bone turnover are routinely performed, whereas additional specific tests are optional, according to the clinical situation. Scintigraphy and bone biopsy are seldom used in the diagnostic procedure. Practical guidelines for the diagnosis of osteoporosis in patients with or without pain are discussed. Diagnostic investigations should only be performed, if the patients gain benefit from it concerning prophylaxis or therapy.