Waiting for an elevated FSH – Too late a marker of reduced ovarian reserve?

Authors

  • Kalani Mudhitha Kahapola Arachchige,

    Corresponding author
    • Western Diagnostic Pathology, Myaree, WA, Australia
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  • Robert Wardrop,

    1. PathWest Laboratory Medicine, Department of Biochemistry, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
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  • Ee Mun Lim,

    1. PathWest Laboratory Medicine, Department of Biochemistry, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
    2. Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Perth, WA, Australia
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  • Bronwyn Stuckey,

    1. Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Perth, WA, Australia
    2. Keogh Institute for Medical Research, Perth, WA, Australia
    3. School of Medicine and Pharmacology, University of Western Australia, Nedlands, WA, Australia, WA, Australia
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  • Narelle Hadlow

    1. Western Diagnostic Pathology, Myaree, WA, Australia
    2. PathWest Laboratory Medicine, Department of Biochemistry, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
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Correspondence: Dr Kalani Mudhitha Kahapola Arachchige, Department of Endocrinology and Diabetes, Royal Perth Hospital, 197 Wellington Street, Perth, WA 6000, Australia. Email: kalanimuditha@yahoo.com

Abstract

Aim

To assess age at which median follicle-stimulating hormone (FSH) is elevated above 10 U/L.

Background

Fertility and ovarian reserve decrease over the 4th decade with evidence that sensitive markers such as anti-Mullerian hormone fall even earlier. Despite its limitations, a basal or day 2–3 FSH is commonly used to assess ovarian reserve with levels over 10 U/L often used as a cut-point for further investigations.

Methods

Women referred to a community laboratory for ‘hormone testing’, including FSH and oestradiol (n = 40 254), were included in a retrospective analysis. Cases excluded were those with suppressed FSH (<1 U/L) who were likely on the oral contraceptive pill or pregnant and those with increased oestradiol (>500 pmol/L) who were likely approaching mid-cycle or pregnant. Remaining cases (n = 32 445) were analysed in five-year age bands for FSH median, mean, and 2.5 and 97.5 percentiles.

Results

Median FSH remained consistently low (≤5 U/L) in women ≤35 years of age and was 6 U/L in 35- to 40-year-olds. The mean FSH and 97.5 percentile increased steadily. The 97.5th percentile was 10 U/L or lower in women up to 30 years of age.

Conclusions

Follicle-stimulating hormone is a late indicator of known reducing ovarian reserve, and in this study, median FSH did not increase over 10 U/L until >45 years of age. FSH levels >9 U/L were above the 97.5th percentile in those <25 years of age. If fertility is a concern, FSH levels persistently above age-specific medians in women under 40 years may prompt earlier follow-up with more sensitive tests for ovarian reserve.

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