Hormone Panel Explained: What Testosterone, Estrogen, LH, FSH, and Prolactin Actually Mean on Your Lab Report

Hormone panels generate some of the most confusing lab reports people encounter. The values are often unfamiliar, the reference ranges are wide, and the relationship between individual hormones and symptoms is rarely straightforward. A testosterone of 320 ng/dL – is that low? It depends on the lab’s reference range, the clinical context, the time of day the sample was drawn, and what symptoms are present. A single number without context is rarely sufficient.

This article covers the major reproductive and pituitary hormones tested in both men and women – what each measures, what the reference ranges mean, what causes abnormalities, and how the pattern of values tells a more complete story than any single number.

How the Hormonal Axis Works: The HPG Axis

Before interpreting individual hormone values, it’s essential to understand the hypothalamic-pituitary-gonadal (HPG) axis – the three-tier control system that regulates reproductive hormones.

Hypothalamus → secretes GnRH (gonadotropin-releasing hormone) in pulses ↓ Pituitary gland → secretes LH (luteinizing hormone) and FSH (follicle-stimulating hormone) ↓ Gonads (testes or ovaries) → secrete testosterone, estrogen, and progesterone

This is a feedback system: rising sex hormone levels signal back to the hypothalamus and pituitary to reduce GnRH, LH, and FSH output. Falling sex hormone levels cause LH and FSH to rise.

This feedback relationship is the single most important concept for interpreting hormone panels. When sex hormone levels are low, the cause is either:

1. Primary hypogonadism: The gonads are failing – LH and FSH will be high (the pituitary is working hard trying to stimulate unresponsive gonads)
2. Secondary hypogonadism: The pituitary or hypothalamus is failing – LH and FSH will be low or inappropriately normal (the gonads are capable but not receiving adequate stimulation)

This distinction is clinically critical because treatment and prognosis differ fundamentally.

LH (Luteinizing Hormone)

LH is produced by the pituitary gland. In men, LH stimulates Leydig cells in the testes to produce testosterone. In women, LH stimulates ovulation (the LH surge triggers egg release) and stimulates the corpus luteum to produce progesterone after ovulation.

Normal ranges:

Men:

• 1.7-8.6 mIU/mL (reference ranges vary by laboratory)

Women:

• Follicular phase: 2.4-12.6 mIU/mL
• Midcycle ovulatory surge: 14-96 mIU/mL (dramatically higher at ovulation)
• Luteal phase: 1.0-11.4 mIU/mL
• Postmenopausal: 7.7-58.5 mIU/mL (significantly elevated after menopause)

Elevated LH:

• In men: primary testicular failure (Klinefelter syndrome, testicular damage from infection, radiation, surgery, or trauma). The pituitary is trying to stimulate failing testes.
• In women: primary ovarian insufficiency (premature ovarian failure), menopause, PCOS (characteristically elevated LH with elevated LH:FSH ratio)

Low LH:

• In men and women: hypothalamic or pituitary dysfunction (hypopituitarism), high-dose exogenous sex hormone use (anabolic steroids suppress LH), hyperprolactinemia (prolactin suppresses GnRH/LH), Kallmann syndrome (congenital GnRH deficiency)
• In men: secondary hypogonadism – the testes could produce testosterone with adequate LH stimulation, but the signal isn’t coming

FSH (Follicle-Stimulating Hormone)

FSH is also produced by the pituitary. In men, FSH stimulates Sertoli cells in the testes to support sperm production (spermatogenesis). In women, FSH stimulates follicle growth in the ovaries and estrogen production.

Normal ranges:

Men:

• 1.5-12.4 mIU/mL

Women:

• Follicular phase: 3.5-12.5 mIU/mL
• Midcycle: 4.7-21.5 mIU/mL
• Luteal phase: 1.7-7.7 mIU/mL
• Postmenopausal: 25.8-134.8 mIU/mL

Day 3 FSH (measured on the third day of the menstrual cycle) is used as a marker of ovarian reserve – a woman’s remaining egg supply and ovarian function. Elevated day 3 FSH indicates diminished ovarian reserve and is used in fertility evaluation.

Elevated FSH:

• In men: indicates primary testicular failure affecting sperm production (Sertoli cell failure, cryptorchidism complications, chemotherapy damage). Elevated FSH in a man with azoospermia suggests a significant impairment of sperm production.
• In women: diminished ovarian reserve, premature ovarian insufficiency, menopause

Low FSH:

• Same pattern as low LH – hypopituitarism, hyperprolactinemia, exogenous hormone suppression

Testosterone

Testosterone is the primary male sex hormone – produced mainly by the testes in men and in smaller amounts by the ovaries and adrenal glands in women.

In Men

Forms measured:

• Total testosterone: All testosterone in the blood, including protein-bound and free fractions. The most commonly ordered test.
• Free testosterone: The unbound, biologically active fraction (~2-3% of total). More relevant clinically because only free testosterone can enter cells and exert effects.
• Bioavailable testosterone: Free testosterone plus albumin-bound testosterone (also biologically available).

Normal range for total testosterone in men: 300-1000 ng/dL (9.2-34.7 nmol/L) – ranges vary significantly between laboratories. The AUA defines hypogonadism at below 300 ng/dL in men with symptoms.

Why the time of testing matters critically: Testosterone follows a strong diurnal (daily) rhythm – it peaks in the morning (typically 7-10am) and reaches a trough in the afternoon and evening. A sample drawn at 3pm can be 20-30% lower than a morning sample in the same individual. Testosterone should be measured in the morning (before 10am) for accurate clinical interpretation. Afternoon values that are mildly low are frequently normal when repeated in the morning.

What low testosterone in men causes:

• Reduced libido and sexual function
• Erectile dysfunction (though this has multiple causes)
• Fatigue, reduced energy and motivation
• Reduced muscle mass and strength
• Increased body fat (particularly visceral)
• Mood changes, depression
• Reduced bone density (long-term low testosterone increases osteoporosis risk)
• Reduced red blood cell production (mild anemia)
• Infertility (testosterone in the testes, not blood, is required for sperm production)

Primary vs secondary hypogonadism in men:

• Low testosterone + high LH/FSH = primary hypogonadism (testicular failure)
• Low testosterone + low/normal LH/FSH = secondary hypogonadism (pituitary or hypothalamic failure, or exogenous testosterone/anabolic steroid suppression)

Causes of secondary hypogonadism in men (beyond pituitary disease): Obesity (adipose tissue converts testosterone to estrogen through aromatization, and obesity-related factors suppress LH), sleep apnea, chronic illness, opioid medications, glucocorticoids, and anabolic steroid use (which profoundly suppresses the HPG axis – sometimes for years after discontinuation).

In Women

Normal range for total testosterone in women: 15-70 ng/dL (though ranges vary considerably and many labs use outdated reference ranges)

Testosterone in women contributes to libido, energy, muscle mass, and bone density. It’s also the direct precursor to estradiol (via aromatization).

Elevated testosterone in women is associated with:

• Polycystic ovary syndrome (PCOS) – the most common cause of androgen excess in women; elevated total or free testosterone with clinical features of hyperandrogenism (hirsutism, acne, irregular periods)
• Congenital adrenal hyperplasia (CAH) – particularly non-classical 21-hydroxylase deficiency
• Adrenal or ovarian tumors (rapidly rising testosterone, very high levels)
• Exogenous androgen use

Low testosterone in women is associated with reduced libido, fatigue, and reduced sense of wellbeing, though the evidence for testosterone therapy in women is more limited than in men and is not universally standard.

Estrogen (Estradiol / E2)

The most clinically relevant estrogen for testing purposes is estradiol (E2) – the most potent form. Estrone (E1) and estriol (E3) are also estrogens but are measured in more specific contexts.

Normal ranges for estradiol (E2):

Women (premenopausal):

• Follicular phase: 15-350 pg/mL (highly variable)
• Midcycle peak: 100-500 pg/mL (at ovulation)
• Luteal phase: 30-450 pg/mL

Women (postmenopausal): below 10-20 pg/mL

Men: 10-40 pg/mL

Elevated estradiol in women: Interpretation is highly cycle-phase dependent. Elevated mid-cycle estradiol is normal. Elevated in the follicular phase may indicate ovarian cysts or tumors, exogenous estrogen use, or liver disease (which impairs estrogen metabolism).

Low estradiol in women: Primary ovarian insufficiency, menopause, hypothalamic amenorrhea (low body weight, excessive exercise, severe stress causing hypothalamic GnRH suppression), hyperprolactinemia.

Elevated estradiol in men: Obesity (aromatization of testosterone to estrogen in adipose tissue), liver disease, testicular tumors (some are estrogen-secreting), exogenous estrogen.

Elevated estrogen in men produces: gynecomastia (breast tissue development), reduced libido, erectile dysfunction, and can suppress testosterone production.

Prolactin

Prolactin is produced by the pituitary and stimulates milk production. In non-pregnant, non-breastfeeding individuals, prolactin levels should be low. Elevated prolactin (hyperprolactinemia) has important consequences because prolactin directly suppresses GnRH and LH/FSH – producing secondary hypogonadism.

Normal ranges:

• Men: 2-18 ng/mL
• Non-pregnant women: 2-29 ng/mL
• Pregnant women: up to 200-400 ng/mL
• Breastfeeding women: can remain elevated for months

What causes elevated prolactin:

Physiological (normal):

• Pregnancy and breastfeeding
• Sleep (prolactin peaks during sleep)
• Stress (physical and psychological)
• Sexual activity
• Nipple stimulation

Pathological:

• Prolactinoma: A benign pituitary adenoma that secretes excess prolactin – the most common pituitary tumor. Ranges from microadenoma (below 10mm) to macroadenoma (above 10mm). Prolactin levels in prolactinoma are often above 200 ng/mL; very high levels (above 1000 ng/mL) essentially confirm prolactinoma.
• Medications: The most common non-physiological cause in clinical practice. Drugs that block dopamine (which normally suppresses prolactin) raise prolactin: antipsychotics (haloperidol, risperidone, olanzapine), metoclopramide, domperidone, certain antidepressants, antihypertensives (methyldopa, verapamil), opioids.
• Primary hypothyroidism: TRH (which rises in hypothyroidism) also stimulates prolactin release.
• Other pituitary tumors: Compressing the pituitary stalk, interrupting dopamine delivery from the hypothalamus.
• Renal failure: Impaired prolactin clearance.

Clinical effects of hyperprolactinemia:

• In women: menstrual irregularities or amenorrhea, infertility, galactorrhea (milk production without pregnancy), reduced libido
• In men: reduced libido, erectile dysfunction, gynecomastia, infertility, galactorrhea (rare)
• In both: secondary hypogonadism with low LH/FSH and low sex hormone levels

The hook effect: Very high prolactin levels (>1000 ng/mL) can paradoxically produce a falsely normal or low result in some immunoassays due to antibody saturation. If a large pituitary mass is identified but prolactin appears normal or only mildly elevated, request a dilution study.

Anti-Müllerian Hormone (AMH) – Ovarian Reserve

AMH is produced by ovarian follicles and is the most reliable marker of ovarian reserve (the remaining egg supply).

Normal range: Approximately 1.0-4.0 ng/mL in reproductive-age women (varies by lab and age)

• High AMH (above 4-5 ng/mL): Suggests high follicle count – seen in PCOS. Also predicts higher risk of ovarian hyperstimulation syndrome (OHSS) with fertility treatment.
• Low AMH (below 1.0 ng/mL, with lower values being more concerning): Diminished ovarian reserve. AMH below 0.5-1.0 ng/mL indicates significantly reduced ovarian reserve.

AMH doesn’t fluctuate significantly with the menstrual cycle (unlike day 3 FSH) and can be measured at any point in the cycle, making it practically convenient for fertility assessment.

Progesterone

Progesterone is produced by the corpus luteum after ovulation and by the placenta during pregnancy. It prepares the uterine lining for implantation and maintains pregnancy.

Clinical use: A mid-luteal phase progesterone (measured approximately 7 days after ovulation, typically around day 21 in a 28-day cycle) confirms that ovulation occurred.

Interpretation:

• Below 3 ng/mL: Suggests anovulation (no ovulation occurred)
• 3-10 ng/mL: Borderline – ovulation may have occurred but luteal phase may be inadequate
• Above 10 ng/mL: Confirms ovulation

In a cycle where ovulation has been confirmed or timed precisely, levels above 15-20 ng/mL are associated with better luteal function. In early pregnancy, progesterone is used to assess viability – though a single value is often less useful than the trend over multiple measurements.

Common Hormone Panel Scenarios

Low testosterone + high LH and FSH in a man: Primary testicular failure. Further workup may include karyotype (to rule out Klinefelter syndrome, 47XXY), semen analysis, and assessment of reversible causes.

Low testosterone + low LH and FSH in a man: Secondary hypogonadism. Evaluate for pituitary disease (MRI pituitary), hyperprolactinemia, medications, obesity, sleep apnea, and hypothyroidism.

Elevated LH, low-normal FSH, elevated testosterone in a woman with irregular periods, acne, and hirsutism: Classic PCOS hormonal pattern. An elevated LH:FSH ratio (above 2:1 or 3:1) is a supporting finding, though not required for diagnosis.

High prolactin + low LH, FSH, and testosterone/estradiol: Hyperprolactinemia causing secondary hypogonadism. Review medications first (dopamine-blocking drugs are the most common cause). If no medication cause, pituitary MRI to look for prolactinoma.

High FSH and LH + low estradiol in a woman under 40: Premature ovarian insufficiency. Confirmed by two measurements more than 4 weeks apart.

Frequently Asked Questions

My testosterone is 280 ng/dL. Is that low? It’s below the 300 ng/dL threshold many guidelines use to define low testosterone in men, but the number alone doesn’t make the diagnosis. The time of testing (was it morning?), your symptoms, your LH and FSH (to determine if it’s primary or secondary), and other clinical factors all matter. A value of 280 on a morning sample in a man with classic symptoms of hypogonadism is more meaningful than a 280 on a 3pm sample in an asymptomatic man.

Why do my hormone levels change throughout the month? Because the hormonal system is a dynamic cycle, not a static state. Estrogen, progesterone, LH, and FSH all vary substantially across the menstrual cycle. Testing a woman’s hormones without knowing where she is in her cycle is like taking a snapshot of a moving object – the result depends entirely on the moment it was captured. For women of reproductive age, the cycle day of testing needs to be recorded and referenced against cycle-phase specific reference ranges.

My prolactin is 35 ng/mL. Should I be worried? Mildly elevated prolactin (up to 3-4x upper limit of normal) is frequently transient and non-pathological. Stress, the timing of the blood draw relative to sleep, physical activity before the test, and even nipple stimulation can transiently raise prolactin. A single mildly elevated result should be confirmed with a repeat fasting morning sample before pursuing further investigation. Persistently elevated prolactin warrants medication review and consideration of pituitary imaging.

What’s the difference between total and free testosterone? Total testosterone measures all testosterone – both bound to proteins (mainly sex hormone-binding globulin and albumin) and unbound. Only the free fraction (approximately 2-3% of total) is biologically active – it can enter cells and exert effects. In conditions where SHBG is elevated (obesity, insulin resistance, hypothyroidism, aging), total testosterone can look normal while free testosterone is low. Free testosterone measurement is particularly useful when SHBG abnormalities are suspected.

My AMH is 0.8. What does that mean for fertility? An AMH of 0.8 ng/mL indicates diminished ovarian reserve – fewer remaining follicles than expected for your age. It doesn’t mean you can’t conceive, but it suggests reduced time before menopause and potentially a poorer response to ovarian stimulation in IVF. The clinical implications depend on your age, other fertility factors, and your reproductive goals. This should be discussed with a reproductive endocrinologist.

Disclaimer

This article is for educational purposes only and does not constitute medical advice. Hormone test interpretation is highly context-dependent and requires evaluation by a qualified healthcare provider who can account for your symptoms, cycle timing, medication history, and full clinical picture. Do not make treatment decisions based on isolated hormone values without medical guidance.

References

1. Bhasin S, Brito JP, Cunningham GR, et al. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology & Metabolism. 2018;103(5):1715-1744. https://doi.org/10.1210/jc.2018-00229
2. Melmed S, Casanueva FF, Hoffman AR, et al. Diagnosis and treatment of hyperprolactinemia: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology & Metabolism. 2011;96(2):273-288. https://doi.org/10.1210/jc.2010-1692
3. Azziz R, Carmina E, Chen Z, et al. Polycystic ovary syndrome. Nature Reviews Disease Primers. 2016;2:16057. https://doi.org/10.1038/nrdp.2016.57
4. Practice Committee of the American Society for Reproductive Medicine. Testing and interpreting measures of ovarian reserve. Fertility and Sterility. 2015;103(3):e9-e17. https://doi.org/10.1016/j.fertnstert.2014.12.093
5. Spratt DI, Crowley WF Jr, Butler JP, Hoffman AR, Crowley WF, Beitins IZ. Pituitary LH and FSH secretion and responsiveness in women with hyperprolactinemia. Journal of Clinical Endocrinology & Metabolism. 1984;59(3):472-478. https://doi.org/10.1210/jcem-59-3-472
6. National Institute of Child Health and Human Development (NICHD). Hormones and fertility. https://www.nichd.nih.gov/health/topics/infertility
7. MedlinePlus – National Library of Medicine. Hormone tests. https://medlineplus.gov/hormones.html
8. Endocrine Society. Patient guides – testosterone. https://www.endocrine.org/patient-engagement/endocrine-library/testosterone
9. American College of Obstetricians and Gynecologists. Primary ovarian insufficiency in adolescents and young women. Obstetrics & Gynecology. 2014;124(1):193-197. https://doi.org/10.1097/01.AOG.0000451757.51964.98
10. Handelsman DJ, Hirschberg AL, Bermon S. Circulating testosterone as the hormonal basis of sex differences in athletic performance. Endocrine Reviews. 2018;39(5):803-829. https://doi.org/10.1210/er.2018-00020