AMH Measurement Timing During the Menstrual Cycle
AMH can be measured at any time during the menstrual cycle without clinically significant impact on interpretation, as the hormone remains relatively stable throughout the cycle. 1, 2
Evidence Supporting Cycle-Independent Timing
The key advantage of AMH over other ovarian reserve markers is its minimal fluctuation across the menstrual cycle:
AMH exhibits relatively stable expression throughout the menstrual cycle, making it an attractive determinant of ovarian activity that does not require specific cycle day timing. 2
While statistically significant differences exist between follicular and luteal phases (approximately 11.5% variation), these fluctuations are not large enough to alter clinical interpretation or change the timing requirements for AMH measurement in current practice. 3, 4
The American Society of Clinical Oncology states that AMH represents the best endocrine marker for assessing age-related decline in ovarian reserve in healthy women, without specifying cycle day requirements. 1
Contrast with FSH Requirements
This cycle-independent nature distinguishes AMH from FSH testing:
FSH must be measured during cycle days 2-5 of the menstrual cycle for accurate ovarian function assessment. 1
For women with amenorrhea, FSH should be measured randomly rather than waiting for a specific cycle day. 1
Estradiol levels should be measured alongside FSH during the early follicular phase (days 2-3) to help interpret FSH results, as normal FSH with elevated estradiol may mask diminished ovarian reserve. 1
Technical Considerations More Important Than Timing
The significant technical issues regarding AMH assays—including lack of international standardization and variability in sample handling—affect result interpretation more than menstrual cycle timing. 1
Age-specific reference ranges are vital for AMH interpretation, as levels are high in adolescence and fall with age, particularly after menopause. 1
Strong positive correlations exist between follicular and luteal AMH levels across all ovarian response groups (hypo-response, normo-response, and hyper-response), with no statistically significant differences in these correlations. 3
Clinical Caveats
The timing issue becomes relevant only for infertile women with AMH levels near cut-off values, where the 11.5% variation between phases could theoretically influence clinical decision-making. 3
AMH has no established diagnostic value for premature ovarian insufficiency, and no recommendations exist for using AMH in this diagnosis. 1
AMH should not be used as primary surveillance in asymptomatic at-risk women; testing should be triggered by menstrual changes or symptoms of premature ovarian insufficiency. 1