Waning estrogen in post-menopausal women is a major cause of oxidative stress, a powerfully destructive force that causes cell damage and bone loss. Identifying the presence of oxidative stress in an individual with osteoporosis would therefore be extremely important. 

In my book, The Whole-Body Approach to Osteoporosis, I explain how biomarkers (lab tests) can be used as therapeutic targets to indirectly monitor changes in bone health and use them to direct therapy. When specific lab tests related (directly or indirectly) to bone health are found to be abnormal, changes in diet and supplemental nutrition can be directed to cause a positive change. Labs can then be retested after 3 to 4 months to determine therapeutic effectiveness. If there is improvement, the patient and health care provider are reassured that they are on the correct therapeutic path. If not, a change in therapy can be applied.
In the case of waning estrogen, serum lipid peroxides and urine 8-hydroxy-2-deoxyguanosine (8OH2dG) can be used to determine oxidative stress levels in individuals with osteoporosis. In my book, I cite several examples were patients’ bone health improved and fracture risk was reduced by using these labs to help direct therapy. In research published in Clinical Chemistry and Laboratory Medicine, Cervellati et al. demonstrate this same negative correlation between bone density and lipid hydroperoxides in post-menopausal women.
This is another example of how the assessment of changes in bone quality, as can be inferred through lab testing, provides intermediate indicators of bone health to help guide therapy.
Cervellati et al., 2012, Bone mass density selectively correlates with serum markers of oxidative damage in post-menopausal women, Clin Chem Lab Med, doi:10.1515/cclm-2012-0095.