Osteopenia is diagnosed by measuring BMD at the hip, forearm, or spine. The gold standard test for measuring BMD is a dual-energy x-ray absorptiometry (DEXA) scan, and osteopenia is diagnosed when BMD is 1−2.5 standard deviations below the average BMD for a young, healthy individual of the same sex. When measuring BMD, this is referred to as a T-score, and therefore a T-score between −1 and −2.5 is diagnostic for osteopenia. Similarly, a T-score of −2.5 or lower is diagnostic for osteoporosis.[1]
After diagnosis, blood tests are used to check levels of calcium, phosphorus, vitamin D, thyroid hormones, parathyroid hormone, and testosterone in men, as well as to assess liver and kidney function. These tests can help identify underlying issues that may be contributing to reduced BMD.[1][2]