title: Updated assays for inhibin B and AMH provide evidence for regular episodic secretion of inhibin B but not AMH in the follicular phase of the normal menstrual cycle.
abstract: OBJECTIVE
  What is the daily variation in serum inhibin B (InhB) and anti-Müllerian hormone (AMH) in relation to the LH surge in women of reproductive age.
  
  
  CONCLUSIONS
  AMH is secreted in a biphasic follicular/luteal pattern in women with higher AMH secretion, while InhB secretion is episodic in the early to mid-follicular phase and immediately after the LH surge but not in the luteal phase.
  
  
  BACKGROUND
  In women of reproductive age with a mean serum AMH >1 ng/ml, levels are highest in Days 2-7 of the cycle. InhB concentrations are highest in the follicular phase of the cycle.
  
  
  METHODS
  In this cohort study conducted in an academic center, blood samples were collected daily from 20 women during one normal menstrual cycle.
  
  
  METHODS
  Regularly menstruating 30- to 40-year-old women had daily serum InhB, AMH, LH and FSH levels measured. Intracycle variability of InhB and AMH were assessed after aligning to the LH surge.
  
  
  RESULTS
  When classified into quartiles of AMH concentration, the lowest AMH levels did not vary across the cycle; the highest AMH levels showed a mid-follicular increase, mid-cycle decrease and mid-luteal increase. A surge of InhB was noted following the LH surge in 16/20 cycles. Episodic increases in InhB occurred in 17/20 cycles prior to the LH surge. In the luteal phase, InhB decreased or became undetectable and did not demonstrate episodic secretion. Old and new assays for AMH and InhB were compared in all samples, with the AMH assays demonstrating good correlation (Rsq = 0.9625) but the InhB assays showing less correlation (Rsq = 0.4903).
  
  
  CONCLUSIONS
  The study population is small and in the mid-to-late reproductive age group. Single daily sampling may not detect more frequent variability (i.e. pulses) in hormone levels.
  
  
  CONCLUSIONS
  These data suggest different regulatory mechanisms for InhB and AMH secretion, and confirm an 'aging ovary' pattern of AMH and InhB secretion, which is consistent with decreased ovarian reserve. We also demonstrated comparability of the AMH Gen II assay with the previous version in standard usage but our data raised concerns about comparability of the InhB Gen II assay.
  
  
  BACKGROUND
  General Clinical Research Center for phlebotomy work has been supported in part by NIH grant UL1RR024986. Recruitment and data analyses were supported by the Center for Integrated Approaches to Complex Diseases (SD Harlow, Director). The authors report no conflicts of interest.
  
  
  BACKGROUND
  N/A.
authors.affiliation: Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, USA.
authors.forename: John F
authors.initials: JF
authors.lastname: Randolph
authors.forename: Siobán D
authors.initials: SD
authors.lastname: Harlow
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Helmuth
authors.forename: Huiyong
authors.initials: H
authors.lastname: Zheng
authors.forename: Daniel S
authors.initials: DS
authors.lastname: McConnell
mesh_terms: D000328:Adult; D054304:Anti-Mullerian Hormone / Q000097:blood / Q000378:metabolism*; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D005498:Follicular Phase / Q000097:blood*; D006801:Humans; D007265:Inhibins / Q000097:blood / Q000378:metabolism*; D008183:Luteal Phase / Q000097:blood; D007986:Luteinizing Hormone / Q000097:blood; D008597:Menstrual Cycle / Q000097:blood; D010507:Periodicity; D011933:Reagent Kits, Diagnostic / Q000592:standards
chemical_list: D011933:Reagent Kits, Diagnostic; C422364:inhibin B; D007265:Inhibins; D054304:Anti-Mullerian Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone
keywords: anti-Müllerian hormone; inhibin B; menstrual cycle variability; ovarian reserve; reproductive aging