Hormones shape libido, and after 40 they shift: testosterone drifts down in men, estradiol and progesterone begin to swing in women, and thyroid problems become more common in both. But desire also depends on sleep, stress, mood, medications and the relationship itself, and those often change at the same age. A panel shows which part is hormonal. It cannot show the rest, which is why a clinician asks.
The hormones that matter
- Testosterone, total and free, with SHBG. It drives desire in men and contributes in women, and free testosterone is the number that counts.
- Estradiol. In women, falling estradiol changes vaginal tissue and can make sex uncomfortable, which lowers desire on its own. In men, both too little and too much affect libido.
- Progesterone, which shifts sleep and mood in women as ovulation becomes irregular.
- TSH, Free T4 and Free T3. An underactive thyroid lowers energy and libido together.
- DHEA-sulfate, an adrenal hormone that declines with age and feeds into both testosterone and estradiol.
What else moves desire after 40
Sleep, stress, mood, alcohol and a number of common medications, antidepressants and some blood pressure drugs among them, all reduce libido, and several of them tend to arrive in the same decade. A relationship that has changed matters too. None of that appears on a lab report, and a plan that ignores it treats the wrong thing.
Why the panel comes before any plan
The bloodwork separates the physical contributors from the rest. Low free testosterone, an underactive thyroid or low iron are concrete and addressable. If the panel is clean, that is useful too: it points the conversation toward sleep, medications and stress with the blood questions already answered.
How Regener8 approaches it
You share your history privately through a clinical intake, draw the full panel at LabCorp, and go through both with a board certified clinician on a private 30 minute video visit. Any plan is built around your numbers and what you actually want, and nothing is assumed from a questionnaire.
Last updated
April 10, 2026
