Quick answer: Androstenedione is a precursor hormone made by the adrenal glands and the ovaries or testes, and the body converts it into testosterone and an estrogen called estrone. Higher levels in women are often seen with polycystic ovary syndrome and have been linked with lower insulin sensitivity, and in a controlled trial in young men, taking androstenedione raised estrogen rather than testosterone.
Androstenedione is a steroid hormone that most people have never heard of, even though it sits right in the middle of the body’s sex hormone pathway. The adrenal glands and the ovaries or testes make it, usually one step after DHEA, and tissues then convert it into testosterone or, through an enzyme called aromatase, into an estrogen called estrone. Because it can move in either direction, androstenedione is often described as a precursor hormone. My articles on DHEA-S and SHBG cover two of its close neighbors, and this article focuses on what androstenedione itself can tell you.
This article is educational. It explains what the marker reflects and how researchers connect it to the deeper mechanisms of aging, so you can have a more informed conversation with your own provider.
What does an androstenedione level tell you?
Androstenedione is usually measured in a blood sample, and newer labs use a method called tandem mass spectrometry, which measures steroid hormones more accurately than older antibody-based tests. Because it is made by both the adrenal glands and the reproductive glands, the result reflects the combined output of both. In women after menopause, the adrenal glands become the main source, and a good share of the estrogen that remains is made from androstenedione in fat tissue.
A higher androstenedione level in women is most often seen alongside polycystic ovary syndrome, where the ovaries make more androgens, and it can also reflect high adrenal output. Some rare inherited adrenal enzyme conditions raise it as well, which is why an unusually high result deserves a careful look with your own provider. A lower level can reflect lower adrenal or ovarian output. Because androstenedione feeds both testosterone and estrogen, it is most useful when it is read alongside testosterone, DHEA-S, SHBG and the estrogens rather than on its own.
How is androstenedione connected to aging and root causes?
Androstenedione is a messenger hormone, so it connects most directly to the way cells signal to one another. Hormones carry instructions between the brain, the adrenal glands, the ovaries or testes, fat tissue and muscle, and changes in that communication are one of the deeper processes researchers link with aging. As adrenal and reproductive hormone output shifts through midlife, the balance between androgens and estrogens shifts too, and androstenedione sits at the point where that balance is set.
Insulin is one of the strongest influences on this pathway. Insulin encourages the ovaries to make more androgens and lowers SHBG, the protein that holds sex hormones in reserve, so insulin resistance tends to push androgen levels up in women. The research below shows how closely androstenedione tracks with lower insulin sensitivity in polycystic ovary syndrome. Nutrient sensing, the way cells respond to fuel and insulin signals, is another process researchers connect with aging, and it ties this hormone back to blood sugar balance.
Fat tissue matters too. Aromatase in fat tissue converts androstenedione into estrone, so more body fat generally means more of this conversion, especially after menopause. Fat tissue that is under strain also releases inflammatory signals, which links this pathway to chronic low-grade inflammation, although the research tying androstenedione itself to inflammation is still early.
From a root-cause view, androstenedione reflects stress and adrenal signaling, sleep and the daily rhythm that drives adrenal hormones, blood sugar and insulin, body composition, physical activity and food quality. Some everyday exposures, such as certain plastic chemicals, are studied for how they interact with hormone signaling, though human evidence for their effect on androstenedione specifically is limited. Genetics plays a part as well, since polycystic ovary syndrome tends to run in families. In practice, steady sleep, regular movement, blood sugar balance and stress support tend to shape this pathway more than any single nutrient does.
What does the research show about androstenedione?
One of the clearest studies of androstenedione as a marker comes from women with polycystic ovary syndrome. In 2014 in the Journal of Clinical Endocrinology and Metabolism, O’Reilly and colleagues compared 86 women who met the Rotterdam criteria for polycystic ovary syndrome with 43 controls matched for age and body mass index, measuring hormones by tandem mass spectrometry and running an oral glucose tolerance test. Every woman with high testosterone also had high androstenedione, but 20 women had high androstenedione with normal testosterone, and only 10 had both in the normal range. Androstenedione showed a strong negative association with insulin sensitivity, and abnormal blood sugar on the glucose test rose from 0 percent in women with normal levels of both hormones, to 14 percent in women with high androstenedione alone, to 25 percent in women with both high. This was a cross-sectional study of a modest number of women, so it shows a link at one point in time rather than cause and effect.
A large pooled analysis looked at androstenedione in women after menopause. In 2002 in the Journal of the National Cancer Institute, the Endogenous Hormones and Breast Cancer Collaborative Group, led by Key and colleagues, reanalyzed individual data from nine prospective studies that included 663 postmenopausal women who developed breast cancer and 1,765 who did not, none of whom were taking hormones when their blood was drawn. Breast cancer risk rose with higher levels of every sex hormone examined, including androstenedione, and the size of the increase for the androgens was similar to that for the estrogens, where women in the top fifth of estradiol had twice the risk of those in the bottom fifth. Because these were observational studies and the hormones convert into one another, the analysis cannot show that androstenedione itself is responsible for the difference.
A randomized trial tested what happens when androstenedione is taken by mouth. In 1999 in JAMA, King and colleagues studied 30 healthy men aged 19 to 29. Twenty of them did eight weeks of whole-body resistance training and were randomized to 300 milligrams of androstenedione a day or placebo, and 10 others took a single 100 milligram dose. Testosterone did not rise with either the single dose or eight weeks of use, but estradiol rose from about 220 to about 310 picomoles per liter after two weeks, estrone rose from about 106 to about 153, and HDL cholesterol fell from 42 to 37 milligrams per deciliter. Strength and muscle fiber gains were similar in both groups. The trial was small and short and included only young men, but it shows clearly how much of this hormone can be routed toward estrogen.
Taken together, these studies suggest that androstenedione is a useful companion to testosterone in women with signs of androgen excess, and that it is best understood as part of a connected hormone network rather than as a single number.
Related reading
If you would like to explore related topics, my articles on DHEA-S, SHBG and fasting insulin and HOMA-IR go deeper. You can also see the specialty tests I commonly recommend on my functional labs page.
Common questions about Androstenedione
Is androstenedione the same as testosterone?
No. Androstenedione is a precursor hormone, and tissues convert it into testosterone or into the estrogen estrone depending on which enzymes they have, so it can feed either side of the hormone balance.
Why test androstenedione if testosterone is normal?
In one study of women with polycystic ovary syndrome, 20 of 86 women had high androstenedione with normal testosterone, so measuring both can show androgen excess that a testosterone result alone would miss.
Can androstenedione raise estrogen?
Yes. In a randomized trial in young men, eight weeks of oral androstenedione raised estradiol and estrone while testosterone stayed the same, which shows how readily the body converts it toward estrogen.
Sources
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before making changes to your diet, exercise, supplements, or medications, especially if you are pregnant, nursing, or managing a health condition.
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