Thyroid function and RED-S risk in elite female GAA athletes across a playing season

Adrianne Wyse; Louise O; Aoife Courtney; Derry O Flynn; Robert McEvoy; Kelly McCarthy; Alison Bransfield; Sean Costelloe; Elaine McCarthy; Paula O; Antoinette Tuthill

doi:10.1530/endoabs.115.EP37

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Endocrine Abstracts (2026) 115 EP37 | DOI: 10.1530/endoabs.115.EP37

IES2025 Research, Audit and Quality Improvement Projects E-Posters (60 abstracts)

Thyroid function and RED-S risk in elite female GAA athletes across a playing season

Adrianne Wyse ^1,3,4 , Louise O’Connell ² , Aoife Courtney ¹ , Derry O Flynn ¹ , Robert McEvoy ¹ , Kelly McCarthy ¹ , Alison Bransfield ¹ , Sean Costelloe ^1,3 , Elaine McCarthy ^1,3, , Paula O’Leary ^1,3 & Antoinette Tuthill ^1,3

Author affiliations

¹Cork University Hospital, Wilton, Cork; ²Cork Ladies Gaelic Football Association; ³University College Cork, Cork 4 Research Ireland

Low energy availability (LEA) arises when an athlete’s energy expenditure exceeds intake, and can lead to Relative Energy Deficiency in Sport (REDS). LEA has been associated with downregulation of the thyroid axis as a metabolic adaptation, and studies to date have shown reduced levels of T3 but variable TSH and T4 results. This study, with CREC approval and supported by Research Ireland, assessed thyroid function (TSH, T3 and T4) in 44 female intercounty GAA players at three time points across a season, as part of a larger investigation. Fifty-six percent of assessed participants were identified as at risk of LEA based on a validated questionnaire(LEAF-Q), while 30% were considered at mild risk of REDS via the International Olympic Committee REDS Clinical Assessment tool (REDS IOC CAT 2).

Mean free T 3 concentration results across the season were:

• pre-season 4.79 ± 0.71 pmol/l[3.7 - 7.5 pmol/l]

• mid-season 5.34 ± 0.79 pmol/l[3.7 - 7.4 pmol/l]

• end-season 4.99 ± 0.87 pmol/l[3.8 - 7.5 pmol/l].Notably, 43% (19) of participants recorded at least one low/subclinically low T3 result and 4 athletes had two low/subclinically low results. However, no significant association was found between thyroid function and LEA risk, determined by LEAF-Q or IOC REDS CAT2. Previous studies in female team sports have a prevalence of low/subclinically low T3 of 10- 13% (Dasa et al,2024.doi:10.1002/ejsc.12129). The prevalence of low/subclinically low T3 in our study is higher than previously reported, however no association was noted with risk of LEA or REDS in this cohort.