Normal Estradiol Reference Ranges Throughout the Menstrual Cycle
An estradiol level of 174 pg/mL (approximately 639 pmol/L) is within normal range for a 23-year-old menstruating female, particularly during the late follicular phase, mid-luteal phase, or around ovulation. 1
Phase-Specific Reference Ranges
The normal estradiol levels vary significantly throughout the menstrual cycle, with the following reference intervals established using highly accurate LC-MS/MS methodology 1:
Early Follicular Phase (Days 1-6 from start of menses)
- Range: 31-771 pmol/L (approximately 8-210 pg/mL) 1
- This represents the baseline hormonal state when levels are at their lowest 2
Late Follicular Phase (Days 7-13, approaching ovulation)
- Range: 104-1742 pmol/L (approximately 28-474 pg/mL) 1
- Estrogen rises progressively as the dominant follicle matures 3
LH Peak/Ovulation (Day 14, mid-cycle)
- Range: 275-2864 pmol/L (approximately 75-780 pg/mL) 1
- Peak estrogen levels typically occur on days 12-14, triggering the LH surge that induces ovulation 3
Early Luteal Phase (Days 15-18)
- Range: 95-1188 pmol/L (approximately 26-324 pg/mL) 1
Mid-Luteal Phase (Days 19-23)
- Range: 151-1941 pmol/L (approximately 41-529 pg/mL) 1
- Estrogen levels rise again during this phase alongside progesterone 3
Late Luteal Phase (Days 24-28)
- Range: 39-1769 pmol/L (approximately 11-482 pg/mL) 1
- When estrogen levels recede, menstruation occurs 3
Interpreting Your Patient's Level
The reported level of 174 pg/mL (approximately 639 pmol/L) falls comfortably within normal ranges for multiple cycle phases 1:
- It is within the upper range for early follicular phase
- Well within the range for late follicular phase
- Below the ovulatory peak but consistent with pre-ovulatory rise
- Within normal for mid-luteal phase
Critical Context for Accurate Interpretation
Timing of sample collection is absolutely critical - the same estradiol level can be normal or abnormal depending on cycle day 2. To properly interpret this result, you must know:
- Exact cycle day when blood was drawn (counting from first day of last menstrual period) 2
- Whether the patient has regular cycles (normal is 21-35 days) 2
- Any hormonal contraceptive use, which suppresses normal estradiol patterns 3, 2
When Further Workup Is Needed
Estradiol levels below 20 pg/mL in premenopausal women warrant investigation for functional hypothalamic amenorrhea or ovarian dysfunction 4. Your patient's level of 174 pg/mL is well above this threshold and does not require further diagnostic workup based on the estradiol value alone 4.
Assay Method Considerations
The reference ranges cited above were established using LC-MS/MS methodology, which is more accurate and sensitive than older immunoassays 1, 5. Radioimmunoassays may report different values and have less reliability at lower concentrations 6. Ensure your laboratory uses a validated, traceable method for accurate interpretation 1.