ACTH Levels by Decade of Life: What Your Results Mean at Every Age

By Sarah Chen, MSN, WHNP-BCMedically reviewed by Elena Vasquez, MD, FACOG

Published Jan 28, 2025Updated Jan 28, 2025Last reviewed Jan 28, 2025

At a glance

Reference range / 10 to 60 pg/mL (morning, fasting; most US labs)
Peak timing / 6 to 8 AM; levels drop 50 to 80% by evening
Pregnancy effect / ACTH rises up to 2 to 3x by the third trimester
Perimenopause shift / cortisol dysregulation can alter HPA feedback; ACTH patterns become less predictable
PCOS relevance / adrenal androgen excess driven by ACTH-mediated 17-hydroxyprogesterone may be elevated
Primary adrenal insufficiency / ACTH high (>200 pg/mL), cortisol low
Secondary adrenal insufficiency / ACTH low or inappropriately normal, cortisol low
Optimal morning ACTH (longevity-medicine consensus) / 10 to 40 pg/mL; upper-normal values warrant investigation

What ACTH Actually Does and Why Women Need to Know the Details

ACTH is a pituitary hormone that tells your adrenal glands to produce cortisol. The relationship runs on a feedback loop: low cortisol prompts the hypothalamus to release CRH, which tells the pituitary to release ACTH, which drives cortisol production. When cortisol rises, it feeds back to suppress both CRH and ACTH. This axis is called the hypothalamic-pituitary-adrenal (HPA) axis, and it does not behave identically in women and men.

Sex steroids modulate every node of this axis. Estrogen amplifies CRH gene expression and increases corticosteroid-binding globulin, which changes how cortisol is measured and transported. Progesterone competes with cortisol at the mineralocorticoid receptor. That means your ACTH result is not a static number: it reflects your hormonal environment on the morning blood was drawn.

The Morning Draw Rule

ACTH follows a circadian rhythm, peaking between 6 and 8 AM and falling to its lowest point around midnight. Studies show a roughly 2-fold diurnal variation, and some labs report variations as large as 3-fold. Blood drawn at noon or later will give a lower number than a morning draw, which can falsely suggest secondary adrenal insufficiency if the clinician does not account for timing. Always draw ACTH between 7 and 9 AM, fasting, in a pre-chilled EDTA tube that is processed within 15 minutes. Missing any of these steps produces an unreliable result.

Why Most Reference Ranges Are Built on Male-Predominant Data

The 10 to 60 pg/mL reference interval reported by most US laboratories is derived from studies that either did not stratify by sex or were predominantly male. Women were historically underrepresented in HPA-axis physiology trials. This is a real evidence gap. What we know from smaller female-specific studies is that ACTH responses to stress, insulin-induced hypoglycemia, and CRH stimulation differ between sexes, and that menstrual cycle phase changes the result. When you review your own lab report, the reference range printed on it was almost certainly not built from women stratified by cycle day, hormonal contraceptive use, or menopausal status.

ACTH in Your 20s: Reproductive Peak and the Cycle Effect

In your 20s, assuming regular ovulatory cycles, ACTH and the entire HPA axis are influenced monthly by fluctuating estrogen and progesterone. During the follicular phase, estrogen enhances CRH sensitivity, which can nudge ACTH slightly higher. In the luteal phase, progesterone's partial anti-glucocorticoid effect may blunt feedback, also affecting the cortisol-ACTH relationship.

A 2003 study in the Journal of Clinical Endocrinology and Metabolism found that healthy women showed significantly higher ACTH responses to ovine CRH in the follicular phase compared with the mid-luteal phase, a cycle-phase difference that is not reflected in a single reference range. If your ACTH is drawn on cycle day 10 versus cycle day 22, the numbers are not directly comparable.

Hormonal Contraception Changes the Picture

If you use combined oral contraceptives, estrogen-containing pills raise corticosteroid-binding globulin, which binds more cortisol, which may paradoxically reduce free cortisol feedback and nudge ACTH slightly upward. Progestin-only methods have a smaller effect. Research has documented increased CBG in women on ethinyl estradiol-containing pills, which complicates interpretation of cortisol and indirectly of ACTH. If you are on combined hormonal contraception and your ACTH looks high-normal, that context matters.

PCOS and Adrenal Androgen Excess

Polycystic ovary syndrome affects approximately 8 to 13% of women of reproductive age. In a subset of women with PCOS, excess androgens come primarily from the adrenal glands rather than the ovaries. ACTH stimulates adrenal 17-hydroxyprogesterone (17-OHP) and DHEA-S production. Women with adrenal-predominant PCOS may show exaggerated ACTH-stimulated 17-OHP responses on a standard cosyntropin stimulation test. ACTH itself is not always elevated in these cases, but the axis is hypersensitive. If you have PCOS and elevated DHEA-S with a normal ACTH, an adrenal ACTH stimulation test may be more informative than a basal ACTH alone.

ACTH in Your 30s: Chronic Stress, Burnout, and Subclinical Dysregulation

The 30s are, for many women, the decade of maximum allostatic load: career, parenting, and potential fertility treatments all running simultaneously. Chronic psychosocial stress activates the HPA axis repeatedly, and animal and human studies suggest females show greater HPA reactivity to psychosocial stressors than males. Whether this translates to chronically elevated basal ACTH in otherwise healthy women is less clear. Basal morning ACTH may remain in range even when the diurnal rhythm is flattened, which a single morning draw does not capture.

What Flattened Cortisol Rhythm Looks Like

A blunted diurnal cortisol slope, meaning cortisol that is not much higher in the morning than at bedtime, is associated with fatigue, mood dysregulation, and metabolic risk. You will not see this on a single fasting ACTH draw. Four-point salivary cortisol testing captures the rhythm better. ACTH is most useful for diagnosing frank insufficiency or excess, not subtle HPA dysregulation.

Fertility Treatments and HPA Axis

Gonadotropin stimulation for IVF produces a sharp rise in estrogen over days, which can transiently increase CRH sensitivity and alter ACTH responses. This is not clinically dangerous in a healthy HPA axis, but women with latent adrenal issues may notice worsening fatigue during stimulation cycles.

ACTH in Your 40s: Perimenopause Begins and HPA Feedback Shifts

Perimenopause typically begins in the mid-40s, though it can start earlier. During this transition, estrogen fluctuates widely before declining. Because estrogen modulates CRH receptor expression and cortisol-binding globulin, fluctuating estrogen in perimenopause alters HPA axis reactivity. Some women notice that their stress response feels more intense, or that they feel wired-but-tired. ACTH itself may remain technically in range during this period, but the timing of peaks and the amplitude of diurnal variation may change.

When to Actually Test ACTH in Perimenopause

Testing ACTH in perimenopause is not routine. The Endocrine Society recommends ACTH measurement primarily when adrenal insufficiency is suspected, when an adrenal mass is found, or when Cushing syndrome is under investigation. If you are in perimenopause and experiencing profound fatigue, hyperpigmentation of skin creases, dizziness on standing, salt cravings, and nausea, those symptoms warrant both an 8 AM cortisol and a paired ACTH. The Endocrine Society's 2016 clinical practice guideline on adrenal insufficiency recommends an 8 AM serum cortisol as the first step, with a threshold of <5 mcg/dL strongly suggesting insufficiency and >15 mcg/dL making it unlikely. ACTH is then paired to determine whether insufficiency is primary (high ACTH) or secondary (low or inappropriately normal ACTH).

Autoimmune Risk Peaks in Women

Primary adrenal insufficiency (Addison disease) has a prevalence of approximately 93 to 140 per million in developed countries, and the autoimmune form is more common in women. Autoimmune polyglandular syndrome type 2, which includes Addison disease alongside autoimmune thyroid disease and type 1 diabetes, disproportionately affects women in their 30s and 40s. If you have Hashimoto thyroiditis or type 1 diabetes and develop unexplained fatigue, your ACTH and cortisol should be checked.

ACTH in Your 50s and 60s: Post-Menopause, Aging, and Interpretation Challenges

After menopause, estrogen drops to persistently low levels, removing its amplifying effect on CRH sensitivity. The HPA axis does not simply quiet down: aging is associated with increased basal cortisol, reduced cortisol variability, and impaired negative feedback. In post-menopausal women, ACTH tends to remain within the standard reference range, but cortisol regulation becomes less precise.

Does ACTH Change with Age?

Cross-sectional studies suggest basal morning ACTH does not change dramatically with age in healthy individuals, but the system becomes less responsive. A study in the Journal of Clinical Endocrinology and Metabolism found that while basal ACTH levels were similar in young and older subjects, the diurnal nadir was higher in older individuals, reflecting impaired suppression. The clinical implication: an ACTH of 55 pg/mL in a 62-year-old post-menopausal woman carries different weight than the same number in a 28-year-old.

Menopausal Hormone Therapy and ACTH

Oral estrogen-containing menopausal hormone therapy raises corticosteroid-binding globulin, just as oral contraceptives do, which again affects how total cortisol is interpreted alongside ACTH. Transdermal estradiol has a smaller effect on CBG. The Menopause Society (formerly NAMS) recommends transdermal estradiol for women at metabolic risk, and this route also avoids the CBG-confounding effect if you are trying to interpret cortisol alongside ACTH.

Adrenal Incidentalomas Increase After 50

Adrenal incidentalomas (adrenal masses found incidentally on imaging done for another reason) are found in approximately 4 to 7% of CT scans in individuals over 50. When an incidentaloma is found, ACTH is part of the workup to rule out ACTH-independent cortisol excess. A suppressed ACTH alongside elevated cortisol points toward autonomous adrenal cortisol production, which has metabolic and bone consequences.

What "Optimal" ACTH Means vs. What "Normal" Means

This distinction matters. The standard lab reference range of 10 to 60 pg/mL defines "normal" as the range that includes 95% of a reference population. "Optimal" is a different question: what range is associated with the lowest risk of adrenal dysfunction, metabolic disease, and HPA dysregulation over time?

Longevity medicine practitioners and functional endocrinologists often target morning ACTH between 10 and 40 pg/mL, reasoning that values in the 40 to 60 pg/mL zone, while technically normal, may reflect a cortisol-feedback system under strain. There is no randomized trial evidence for this tighter target, and it has not been adopted by the Endocrine Society or ACOG guidelines. The distinction the WomanRx editorial board applies is this: a value of 10 to 40 pg/mL in a morning draw is generally reassuring; a value of 40 to 60 pg/mL warrants review of clinical context, symptoms, and a paired cortisol; a value above 60 pg/mL needs a formal workup.

Values below 10 pg/mL with a low cortisol suggest secondary adrenal insufficiency and require pituitary imaging. Values above 200 pg/mL with a low cortisol confirm primary adrenal insufficiency.

Reading the ACTH Result Alongside Cortisol: A Decision Framework

ACTH alone does not tell you enough. The paired interpretation of morning ACTH and morning cortisol is essential.

| Pattern | What It Suggests | |---|---| | ACTH high (>60), cortisol low (<5 mcg/dL) | Primary adrenal insufficiency (Addison disease) | | ACTH low or normal, cortisol low | Secondary or tertiary adrenal insufficiency (pituitary or hypothalamic) | | ACTH high (>60), cortisol high (>20 mcg/dL) | Ectopic ACTH syndrome or Cushing disease | | ACTH low or suppressed, cortisol high | Adrenal adenoma producing cortisol autonomously | | ACTH normal (10 to 40), cortisol normal (10 to 20 mcg/dL), 8 AM draw | No adrenal axis abnormality detected |

A single result landing in the "normal" row does not rule out subclinical Cushing syndrome. The Endocrine Society recommends late-night salivary cortisol, 24-hour urinary free cortisol, or 1 mg overnight dexamethasone suppression testing if Cushing syndrome is clinically suspected, even with a normal morning ACTH.

Conditions That Specifically Affect Women's ACTH Results

Several conditions that disproportionately or exclusively affect women change how ACTH should be interpreted.

Autoimmune Thyroid Disease

Hashimoto thyroiditis affects approximately 5% of women. Hypothyroidism slows cortisol clearance, which may suppress ACTH through enhanced cortisol feedback, potentially masking early primary adrenal insufficiency. If your thyroid disease is poorly controlled, your ACTH may be falsely low-normal. Treating hypothyroidism first, then rechecking adrenal function, is the standard approach.

Endometriosis and Chronic Pain

Chronic pain conditions including endometriosis produce sustained HPA activation. Endometriosis affects approximately 10% of women of reproductive age. Sustained pain-related HPA activation can produce diurnal rhythm flattening. Again, basal ACTH may remain normal even when the system is dysregulated.

Anorexia Nervosa and Hypothalamic Amenorrhea

Caloric restriction and low body weight suppress the hypothalamus. In women with functional hypothalamic amenorrhea, CRH and ACTH may be elevated as part of the stress response that suppresses the reproductive axis. Research has documented elevated CRH and increased cortisol in women with hypothalamic amenorrhea, even with ACTH remaining in the upper-normal range. If you have lost your period due to low weight or excessive exercise, your adrenal axis is likely activated and ACTH context matters.

Pregnancy and Postpartum: The Most Dramatic ACTH Changes of Your Life

Pregnancy changes ACTH physiology more than any other life stage. This section is required reading if you are pregnant, planning pregnancy, or recently postpartum.

The placenta produces its own CRH, a molecule identical to hypothalamic CRH, and this placental CRH rises exponentially across gestation, peaking at term. Plasma CRH levels increase up to 1,000-fold by the third trimester. ACTH rises in parallel, with levels in the third trimester reaching two to three times the non-pregnant reference range. Cortisol also rises, driven by increased CBG and true free cortisol increases. This is physiologically normal in pregnancy. A third-trimester ACTH of 90 to 120 pg/mL is expected, not alarming.

What This Means for Diagnosing Adrenal Disease in Pregnancy

Diagnosing Cushing syndrome in pregnancy is notoriously difficult because the normal pregnancy state mimics Cushing biochemically. ACOG guidance on adrenal disease in pregnancy notes that late-night salivary cortisol is the most reliable screening test in pregnancy because the nighttime nadir is less affected by placental CRH than morning values.

Addison disease in pregnancy is a medical emergency. Adrenal crisis during labor or delivery can be fatal. Women with known primary adrenal insufficiency must receive stress-dose hydrocortisone during labor, typically 25 to 50 mg IV hydrocortisone at the start of labor, followed by maintenance dosing. Delivery teams must be informed in advance.

Postpartum Adrenal Considerations

After delivery, placental CRH disappears abruptly. ACTH and cortisol drop sharply. In some women, particularly those who experienced prolonged labor or hemorrhage, this post-delivery HPA axis drop can unmask latent secondary adrenal insufficiency. Postpartum fatigue is ubiquitous, but if you have profound exhaustion, hypotension, and nausea in the weeks after birth, adrenal function testing is warranted alongside thyroid testing.

Postpartum autoimmune thyroiditis, which affects approximately 7 to 10% of women in the first year after delivery, can also affect cortisol clearance and thus ACTH feedback, as described above. If you are being worked up postpartum, test TSH and free T4 alongside morning cortisol and ACTH.

Lactation

Hydrocortisone (the replacement steroid used in adrenal insufficiency) transfers into breast milk in small amounts. Published data suggest that at replacement doses of 20 to 30 mg per day, infant exposure is approximately 0.4% of the maternal dose, which is considered safe. Women with primary adrenal insufficiency can breastfeed on standard replacement therapy. No dose adjustment for lactation is generally required, but consultation with your endocrinologist before and immediately after delivery is mandatory.

Who Should Actually Get an ACTH Test?

Not everyone needs an ACTH. The test is most useful in specific clinical scenarios.

ACTH is appropriate when you have:

Unexplained fatigue, salt cravings, nausea, and unintentional weight loss (evaluate for adrenal insufficiency)
Hyperpigmentation of skin creases, scars, or gums (a sign of chronically elevated ACTH driving melanocortin receptors)
An adrenal mass found on imaging (to assess autonomous function)
Suspected Cushing syndrome (central weight gain, purple stretch marks, proximal muscle weakness)
Known pituitary disease or prior pituitary surgery (check for secondary adrenal insufficiency)
PCOS with elevated DHEA-S (to evaluate adrenal androgen contribution)
Autoimmune thyroid disease with fatigue disproportionate to TSH levels

ACTH is generally not useful for:

Routine wellness panels without symptoms
General fatigue workup without accompanying cortisol and clinical assessment
Monitoring adrenal replacement therapy (dosing is guided by symptoms and cortisol, not ACTH)

How to Prepare for and Interpret Your ACTH Test

Getting the pre-analytical steps right makes the difference between a useful result and a misleading one.

Draw time: 7:00 to 9:00 AM only. No exceptions.
Fasting: Ideally 8 to 12 hours fasted, though evidence on fasting effect is mixed.
Tube type: EDTA (purple-top) tube, pre-chilled on ice.
Processing: Must reach the lab within 15 minutes and be spun down immediately; ACTH degrades rapidly at room temperature.
Cycle day: If you have regular cycles, note the cycle day on the requisition. Day 1 to 10 (follicular) and day 15 to 26 (luteal) values are not directly comparable.
Medications: Corticosteroids (including topical and inhaled) suppress ACTH. Inform your clinician of all steroid-containing medications.
Stress: Acute physical or psychological stress raises ACTH. If you had a stressful commute or a rough night, that can shift the result.

Always request a same-draw 8 AM serum cortisol. An ACTH result interpreted without a paired cortisol is incomplete.

Frequently asked questions

›What is the optimal ACTH range for women?

Most labs report a reference range of 10 to 60 pg/mL for a morning draw. Longevity medicine practitioners often target 10 to 40 pg/mL as an optimal range, reasoning that upper-normal values may reflect HPA axis strain. This tighter target is not endorsed by the Endocrine Society or ACOG guidelines. Regardless of the number, always interpret ACTH with a paired morning cortisol and your clinical symptoms.

›What is a normal ACTH level by age?

Published reference ranges do not formally stratify by decade in women, which is a known evidence gap. Basal morning ACTH generally remains between 10 and 60 pg/mL across adulthood. In the third trimester of pregnancy, ACTH rises to two to three times the non-pregnant range and values up to 120 pg/mL may be normal. After menopause, ACTH stays within the standard range but diurnal variation becomes less pronounced.

›What does a high ACTH level mean in a woman?

High ACTH (above 60 pg/mL, especially above 100 pg/mL) with a low cortisol strongly suggests primary adrenal insufficiency, meaning the adrenal glands are failing and the pituitary is overdriving them. High ACTH with a high cortisol raises concern for Cushing disease (a pituitary ACTH-secreting tumor) or ectopic ACTH syndrome. High ACTH in late pregnancy is normal. Context is everything.

›What does a low ACTH level mean?

Low ACTH (below 10 pg/mL) paired with a low cortisol suggests secondary adrenal insufficiency, most commonly from pituitary disease, prior corticosteroid use, or pituitary surgery. Low ACTH with normal or high cortisol may indicate an autonomous cortisol-secreting adrenal adenoma. Low ACTH alone, without a low cortisol, rarely requires treatment but warrants pituitary evaluation.

›Can ACTH levels change during the menstrual cycle?

Yes. Research shows that ACTH responses to CRH stimulation are higher in the follicular phase than the mid-luteal phase. Estrogen enhances CRH sensitivity, which can nudge ACTH upward in the first half of your cycle. A single morning basal ACTH does not capture this variation reliably, so note your cycle day when the blood is drawn.

›Does perimenopause affect ACTH?

Fluctuating estrogen in perimenopause alters HPA axis reactivity, though basal morning ACTH usually stays within the standard reference range. The cortisol diurnal rhythm may become less regular. Women in perimenopause who have unexplained fatigue, dizziness, and salt cravings should still have adrenal insufficiency ruled out with an 8 AM cortisol and paired ACTH, rather than attributing all symptoms to menopause.

›How does ACTH change during pregnancy?

Placental CRH, which is identical to hypothalamic CRH, rises exponentially across pregnancy and drives ACTH up to two to three times the non-pregnant reference range by the third trimester. This is normal and expected. After delivery, placental CRH disappears abruptly, ACTH and cortisol drop sharply, and in rare cases this can unmask latent adrenal insufficiency.

›What conditions in women cause elevated ACTH?

Primary adrenal insufficiency (Addison disease), Cushing disease (pituitary ACTH-secreting tumor), ectopic ACTH syndrome, congenital adrenal hyperplasia (including non-classic CAH), and normal third-trimester pregnancy all cause elevated ACTH. Autoimmune polyglandular syndrome type 2, which disproportionately affects women, combines Addison disease with autoimmune thyroid disease and is a common cause of elevated ACTH in women in their 30s and 40s.

›Is ACTH testing useful for PCOS?

Basal ACTH is often normal in PCOS, but the adrenal ACTH stimulation test (cosyntropin test with 17-OHP measurement) can identify women with adrenal-predominant androgen excess. Elevated DHEA-S with normal ACTH on a basal draw may still reflect adrenal hypersensitivity to ACTH-driven stimulation. ACTH testing is most useful in PCOS when DHEA-S is elevated and you need to distinguish adrenal from ovarian androgen sources.

›Can stress raise my ACTH test result?

Yes. Acute physical stress, emotional distress, hypoglycemia, and even a stressful commute before the blood draw can transiently raise ACTH. This is one reason pre-analytical conditions matter: the draw should be done in a calm setting, in the morning, with the patient at rest for at least 15 to 20 minutes before venipuncture.

›What time of day should ACTH be measured?

ACTH must be measured between 7:00 and 9:00 AM. ACTH follows a circadian rhythm and levels can be 50 to 80% lower in the evening than in the morning. A result drawn at 2 PM cannot be compared to the standard 10 to 60 pg/mL morning reference range.

›Can hormonal birth control affect my ACTH level?

Combined estrogen-containing contraceptives raise corticosteroid-binding globulin, which binds more cortisol. This can reduce free cortisol feedback and slightly raise ACTH. The effect on basal ACTH is generally modest but can push a borderline result into the high-normal range. Tell your clinician you are on hormonal contraception whenever adrenal labs are ordered.