Bioavailable testosterone represents the amount of circulating free testosterone along with that bound loosely to albumin, which can easily become available. Decreased bioavailable testosterone in women may be associated with atherosclerosis and cardiovascular disease risk. However, increasing levels may be associated with NAFLD and extremely high levels can also be associated with CVD.
Standard Range: Female 0.5 - 8.5 ng/dL (0.02 - 0.29 nmol/L)
The ODX Range: Female 5.5 - 8.5 ng/dL (0.19 - 0.29 nmol/L
Low levels of bioavailable testosterone may be associated with atherosclerosis and CVD risk (Davis 2015).
High levels of bioavailable testosterone may be associated with non-alcoholic fatty liver disease (Wang X, 2021), and at extremely high levels may be associated with CVD (Davis 2015).
Testosterone is physiologically essential in both men and women. Circulating levels of bioavailable testosterone reflect how much of that testosterone is readily available for use. Research indicates that low levels of bioavailable testosterone (BT), along with low total T, free T, and SHBG, are associated with increased risk of atherosclerosis, cardiovascular events, and total mortality in women. Sufficient BT in women has also been associated with reduced risk of hip fractures. However, extremely high levels may increase risk of CVD, suggesting a U-shaped association and possible involvement of other metabolic factors (Davis 2015).
Higher levels of BT may also be associated with liver disease. A study of 2,117 women in a prospective community-based study found that an elevated BT of 9.55 ng/dL (0.33 nmol/L) and a %BT of 35.45% was associated with NAFLD, while an optimal BT of 6.8 ng/dL (0.23 nmol/L) and a %BT of 26.8% were not associated with this condition (Wang X, 2021).
Davis, Susan R., and Sarah Wahlin-Jacobsen. "Testosterone in women—the clinical significance." The Lancet Diabetes & Endocrinology 3.12 (2015): 980-992.
Wang, Xu et al. “Associations between serum total, free and bioavailable testosterone and non-alcoholic fatty liver disease in community-dwelling middle-aged and elderly women.” Diabetes & metabolism vol. 47,3 (2021): 101199. doi:10.1016/j.diabet.2020.09.007