Unit Converter
Estrone (E1)
(Major Postmenopausal Estrogen – Marker for Ovarian, Adrenal & Peripheral Aromatization Activity)
Synonyms
- Estrone
- E1
- Oestrone (British spelling)
- Aromatized estrogen
- Peripheral estrogen
- Postmenopausal estrogen
Units of Measurement
- pmol/L
- ng/L
- ng/dL
- ng/100 mL
- ng%
- pg/mL
Unit Conversions
1 pg/mL = 3.699 pmol/L
1 pg/mL = 100 ng/dL
1 pg/mL = 1000 ng/L
pg/mL = ng/L
ng/dL = ng% = ng/100 mL
Description
Estrone (E1) is one of the three major estrogens (estradiol E2, estrone E1, estriol E3).
It is the predominant circulating estrogen in postmenopausal women, produced mainly via:
- Peripheral aromatization of androstenedione in adipose tissue
- Adrenal contributions
- Ovarian theca production (in premenopausal women)
Estrone is crucial for evaluating:
- Menopause
- Hypogonadism
- Obesity-related hyperestrogenism
- Aromatase excess
- Feminizing tumors
- Hormone replacement therapy monitoring
Physiological Role
Estrone has weaker biological potency compared to estradiol but is important in:
- Postmenopausal bone health
- Vascular function
- Breast tissue regulation
- Hormonal feedback on pituitary (FSH/LH)
Clinical Significance
Low Estrone Levels
Seen in:
1. Menopause & Premature Ovarian Failure
- E1 decreases significantly
- Used with estradiol + FSH for confirmation
2. Hypogonadism
- Hypothalamic amenorrhea
- Pituitary insufficiency
- Turner syndrome
3. Anorexia / Malnutrition
- Low androgen substrate for aromatization
High Estrone Levels
1. Obesity
- Increased aromatase activity in adipose tissue
- Leads to elevated E1 (hallmark finding)
2. PCOS
- Mild-to-moderate E1 elevation due to increased peripheral conversion
3. Estrogen-Secreting Tumors
- Granulosa cell tumors
- Feminizing adrenal tumors
4. Pregnancy
- Estrone increases along with other estrogens
5. Liver Disease
- Decreased estrogen clearance → high E1
6. Male Hyperestrogenism
- Testicular tumors
- Aromatase excess syndrome
Reference Intervals
(Tietz 8E + Endocrine Society + Mayo + ARUP)
Women (pg/mL)
Premenopausal
- Follicular Phase: 17–200 pg/mL
- Luteal Phase: 20–300 pg/mL
Postmenopausal
- 7 – 40 pg/mL (dominant estrogen after menopause)
Men
- 10 – 60 pg/mL
Children
- Prepubertal: <20 pg/mL
- Pubertal stages show gradual rise
Diagnostic Uses
1. Menopause Evaluation
Estrone becomes the primary estrogen → supports diagnosis with estradiol + FSH.
2. PCOS Assessment
E1 helps assess androgen–estrogen conversion patterns.
3. Infertility Workup
Evaluates:
- Ovarian reserve
- Estrogen imbalance
- HRT monitoring
4. Hyperestrogenism in Men
Rule out:
- Testicular tumors
- Adrenal tumors
- Cirrhosis
- Obesity-related aromatization
5. Aromatase Excess & Feminizing Tumors
E1 often elevated more than E2.
6. Breast Cancer Risk
Estrone elevation linked with postmenopausal breast cancer risk.
Analytical Notes
- Serum sample
- Diurnal variation minimal
- Estrone assays less precise than estradiol at very low levels
- LC-MS/MS preferred for men, children, and postmenopausal women
- Immunoassay interference possible with biotin supplements
Clinical Pearls
- Estrone is the dominant estrogen in postmenopausal women, not estradiol.
- Obesity significantly elevates estrone via adipose aromatase activity.
- E1:E2 ratio is helpful in PCOS evaluation.
- Elevated E1 in men is a red flag for estrogen-producing tumors or severe liver disease.
- Estrone interpretation should always be combined with estradiol, testosterone, LH, FSH, SHBG.
Interesting Fact
Estrone was the first estrogen ever discovered (1929) and earned Adolf Butenandt the Nobel Prize in Chemistry for hormone research.
References
- Tietz Clinical Chemistry & Molecular Diagnostics, 8th Edition - Steroid Hormones.
- Endocrine Society Clinical Guidelines - Female Hormone Testing.
- ASRM Reproductive Endocrinology Standards.
- AACE Hormone Evaluation Guidelines.
- Mayo Clinic Laboratories - Estrone.
- ARUP Consult - Estrogen Profile Interpretation.
- MedlinePlus / NIH - Estrone Test.