<s>[INST] Why do they compare my bones to a 30 year old? [/INST] The classification of low bone density and osteoporosis was standardized against peak bone mass. Adults typically reach peak bone mass around age 30. The scientists used large databases of test results to determine the average for normal peak bone mass, and then the range for low bone mass (osteopenia) and very low bone mass (osteoporosis).

In 1994, the World Health Organization (WHO) reviewed the worldwide data on bone density testing and fracture risk. Prior to this publication, many bone density testing centers reported results by comparing a patient to other patients of the same age. The WHO concluded that, based on studies of older women, reporting the relation of the bone mineral density (BMD) to the average peak bone mineral density of a 30-year old would be more appropriate. Source: American Bone Health. Link: https://americanbonehealth.org/frequently-asked-questions/. Field: Rheumatology. Disease: Ostoeporosis </s>