Estrogen, Progesterone & Testosterone in Women: What They Do & What Happens When They're Off

Women's hormones are not simply a "reproductive" system — they are a whole-body signaling network affecting mood, memory, metabolism, sleep, libido, bone density, cardiovascular health, and immune function. When these hormones fall out of balance — whether due to the monthly cycle, PCOS, perimenopause, or stress — the effects ripple through nearly every system in the body. Understanding what each hormone does is the first step toward taking back control.

The Big Three: An Overview

Most people think of "women's hormones" as a single entity. In reality, the hormonal landscape in women involves a constantly shifting interplay of multiple hormones with distinct — and sometimes opposing — effects. The three most clinically significant are estrogen, progesterone, and testosterone.

Estrogen: The Builder and the Protector

Estrogen is a family of hormones — estrone (E1), estradiol (E2), and estriol (E3) — with estradiol being the most biologically potent and clinically relevant in premenopausal women. Estradiol is produced primarily by the ovaries in response to FSH (follicle-stimulating hormone) from the pituitary gland, with smaller contributions from adipose tissue, the adrenal glands, and — during pregnancy — the placenta.

Estrogen's functions span far beyond reproduction:

• Bone density: Estrogen inhibits osteoclasts (bone-degrading cells) and promotes osteoblast activity, maintaining skeletal integrity. The sharp drop in estrogen at menopause is why women lose bone density rapidly in the first 5–10 years after their last period.
• Cardiovascular protection: Estradiol promotes vasodilation, reduces LDL cholesterol, raises HDL cholesterol, and has anti-inflammatory effects on arterial walls. Premenopausal women have significantly lower rates of cardiovascular disease than men of the same age — an advantage largely attributed to estrogen.
• Cognitive function: Estrogen receptors are distributed throughout the brain, including in the hippocampus (memory), prefrontal cortex (executive function), and limbic system (emotion regulation). Estrogen supports serotonin synthesis, promotes neuroplasticity, and protects against neuroinflammation.
• Skin and connective tissue: Estrogen stimulates collagen production and dermal thickness. The accelerated skin aging many women notice after menopause reflects declining estrogen levels, not simply chronological aging.
• Vaginal and urinary health: The genitourinary tract is rich in estrogen receptors. Declining estrogen causes vaginal dryness, atrophy, and urinary frequency/urgency — collectively called genitourinary syndrome of menopause (GSM).

Progesterone: The Balancer and the Calmer

Progesterone is produced by the corpus luteum (the follicle that released the egg) in the second half of the menstrual cycle — the luteal phase — and by the placenta during pregnancy. It is also produced in small amounts by the adrenal glands.

Progesterone's primary reproductive role is to prepare and maintain the uterine lining for potential implantation and sustain early pregnancy. But its systemic effects are equally important:

• Anti-anxiety and calming: Progesterone is a precursor to allopregnanolone, a potent positive modulator of GABA-A receptors — the same receptors targeted by benzodiazepines and alcohol. Higher progesterone levels (as in the luteal phase and pregnancy) tend to reduce anxiety; falling progesterone (premenstrually or in perimenopause) can cause anxiety, irritability, and sleep disruption.
• Sleep quality: Progesterone promotes NREM deep sleep through its GABA-ergic metabolites. Women with low progesterone frequently report difficulty falling asleep and frequent nighttime waking.
• Counterbalancing estrogen: Estrogen stimulates uterine lining proliferation; progesterone limits it. Without adequate progesterone, estrogen's proliferative effects on the uterus can lead to endometrial hyperplasia and increase cancer risk. This is why hormone replacement therapy in women with an intact uterus always includes progesterone (or a synthetic progestogen).
• Thyroid function: Progesterone supports thyroid hormone action at the cellular level and may counteract some of estrogen's effects on thyroid-binding globulin.

Testosterone: The Underappreciated Women's Hormone

Testosterone is often dismissed as a "male hormone" in the context of women's health — a remarkable oversight, given that the ovaries produce testosterone throughout a woman's reproductive years, and that women's tissues are packed with androgen receptors that depend on testosterone for normal function.

In women, testosterone is produced by both the ovaries and the adrenal glands and circulates at about one-tenth the levels found in men — but this does not mean it is less important. Its roles include:

• Libido and sexual function: Testosterone is the primary driver of sexual desire in women. Low testosterone is the most common hormonal cause of hypoactive sexual desire disorder (HSDD). This is so well-established that testosterone therapy for HSDD in postmenopausal women has been recommended in international guidelines since 2019, though it remains off-label in the U.S.
• Lean muscle mass and strength: Like in men, testosterone drives protein synthesis and muscle fiber growth. Women losing testosterone — as happens through the 30s and 40s, with a sharper drop at menopause — experience progressive loss of muscle mass and strength that worsens metabolic health.
• Mood, motivation, and confidence: Testosterone acts in the brain's reward and motivational circuits. Women with low testosterone frequently describe a loss of drive, reduced assertiveness, and a flattening of emotional engagement.
• Bone density: Both estrogen and testosterone contribute to bone maintenance in women. Androgen receptors in bone respond to testosterone independently of estrogen pathways.

When Hormones Go Wrong: Common Conditions

PMS and PMDD: The Luteal Phase Crash

Premenstrual syndrome (PMS) affects an estimated 75% of menstruating women at some point; premenstrual dysphoric disorder (PMDD), the severe form, affects 3–8%. Both occur in the luteal phase — the two weeks between ovulation and menstruation — and resolve within a few days of menstrual onset.

The hormone picture in PMS/PMDD is not simply "too much estrogen." Current research points to an abnormal sensitivity to normal hormonal fluctuations — particularly the drop in progesterone (and its allopregnanolone metabolite) in the late luteal phase — in genetically predisposed individuals. For some women, this progesterone withdrawal triggers dysregulation of the serotonergic and GABAergic systems, producing mood symptoms, anxiety, irritability, bloating, breast tenderness, and sleep disruption that are not present at other cycle phases.

PCOS: The Androgen Excess Syndrome

Polycystic ovary syndrome (PCOS) affects 6–12% of women of reproductive age, making it the most common endocrine disorder in this population. Despite its name, cysts on the ovaries are neither necessary nor sufficient for diagnosis; the Rotterdam criteria requires any two of three features: irregular or absent ovulation, clinical or biochemical evidence of androgen excess (hirsutism, acne, elevated androgens), and polycystic ovarian morphology on ultrasound.

The hormonal picture in PCOS is complex and varies between individuals, but characteristic features include:

• Elevated LH relative to FSH, disrupting normal follicular development
• Elevated androgens (testosterone, DHEA-S, androstenedione) — causing hirsutism, acne, scalp hair thinning, and irregular periods
• Insulin resistance in 65–70% of PCOS patients, driving hyperinsulinemia that further stimulates ovarian androgen production
• Low sex hormone-binding globulin (SHBG), amplifying the effects of circulating androgens
• Relative progesterone deficiency due to anovulation (no progesterone is made without ovulation)

PCOS is not a one-size-fits-all condition. The "lean PCOS" presentation differs from insulin-resistant PCOS, adrenal-dominant PCOS, and post-pill PCOS in nuanced ways that require personalized evaluation.

Perimenopause: The Decade of Hormonal Turbulence

Perimenopause — the transition to menopause — begins, on average, in the mid-40s and lasts 4–8 years before the final menstrual period. It is not a gradual, smooth decline in hormones. It is characterized by erratic, unpredictable hormonal fluctuations that can be profoundly disruptive.

In early perimenopause, FSH rises as the ovaries become less responsive, driving estradiol levels to surge higher than typical premenopausal levels. These surges can cause breast tenderness, heavy periods, migraines, anxiety, and insomnia. Progesterone declines first — because ovulation becomes less reliable — creating a relative estrogen dominance picture even as overall estrogen is technically still adequate. Later perimenopause brings the more familiar estrogen deficiency symptoms: hot flashes, night sweats, vaginal dryness, and accelerated bone loss.

The most common symptoms of perimenopause include:

• Hot flashes and night sweats (vasomotor symptoms)
• Sleep disruption and insomnia
• Irregular or heavy periods
• Mood changes: anxiety, irritability, depression
• Brain fog and memory lapses
• Weight gain, especially around the abdomen
• Low libido
• Vaginal dryness and pain with intercourse
• Joint aches and muscle pain

Many of these symptoms are mistakenly attributed to "stress" or "aging" rather than to the profound neuroendocrine changes of perimenopause. Proper hormonal evaluation and treatment — when appropriate — can dramatically improve quality of life.

Low Libido and the Hormone-Desire Connection

Hypoactive sexual desire disorder (HSDD) — persistently low sexual interest causing personal distress — affects an estimated 10% of premenopausal women and 30–40% of postmenopausal women. Hormones are a major contributing factor, though not the only one.

The key hormonal drivers of low libido in women include:

• Low testosterone: Most direct driver of sexual desire; natural testosterone levels decline throughout the 20s–40s and drop sharply at menopause (natural or surgical)
• Low estradiol: Contributes to vaginal dryness and discomfort that makes sex painful, effectively suppressing desire as a protective mechanism
• Elevated cortisol: Chronic stress suppresses sex hormone production through the HPA-HPG axis competition — the same precursor (pregnenolone) that makes cortisol competes with sex hormone production
• Elevated prolactin: Seen with certain medications (antipsychotics, some antidepressants, domperidone) and prolactinomas; suppresses GnRH pulsatility and sex hormone production
• Low progesterone: Less directly linked to desire, but indirectly affects libido through anxiety, sleep disruption, and mood

Hormones and Anxiety: The Connection Most Doctors Miss

Anxiety disorders are twice as common in women as in men. Hormonal fluctuations are a significant — and underappreciated — contributor. The mechanisms include:

• Progesterone withdrawal: The premenstrual drop in allopregnanolone reduces GABAergic tone, lowering the threshold for anxiety and panic attacks
• Estrogen and serotonin: Estradiol upregulates serotonin synthesis, serotonin receptors, and the reuptake transporter. Falling estrogen — in the late luteal phase, perimenopause, or postpartum — reduces serotonergic activity and increases vulnerability to low mood and anxiety
• The cortisol connection: Low estrogen impairs the HPA axis response to stress, making it harder to modulate cortisol release and return to baseline after a stressor
• Sleep disruption feedback loop: Hormonal disruption causes sleep loss; sleep deprivation amplifies HPA reactivity and anxiety symptoms, creating a self-perpetuating cycle

Women who notice their anxiety is cyclical — worse in the week before their period, worse since perimenopause began — are often responding to hormonal fluctuations, not to a primary anxiety disorder. Treating the hormonal root cause, rather than only the anxiety symptom, is frequently more effective and better tolerated.

Getting the Right Evaluation

Hormonal testing in women requires careful consideration of cycle timing. Estradiol and progesterone vary dramatically across the menstrual cycle; a single random draw is rarely informative. Standard hormonal evaluation typically includes:

• Day 3 FSH, LH, estradiol (early follicular phase baseline)
• Day 21 progesterone (mid-luteal, approximately 7 days after expected ovulation) — to confirm ovulation occurred and assess luteal adequacy
• Total and free testosterone, SHBG
• DHEA-S (adrenal androgen)
• Thyroid panel (TSH, free T4, free T3, anti-TPO antibodies) — thyroid dysfunction mimics many hormonal symptoms
• Fasting insulin and glucose — especially if PCOS is suspected
• Prolactin — if amenorrhea or galactorrhea is present

Interpreting results in the context of symptoms — not just "normal range" lab flags — is essential. A testosterone level in the bottom 10% of the normal range may be entirely normal for one woman and profoundly symptomatic for another.