Pupiš, MartinBrünn, DavidSýkora, JozefPupišová, ZuzanaBako, Kristián2026-05-042026-05-0420260393-36601827-1812https://doi.org/10.23736/S0393-3660.25.05856-5https://repo.umb.sk/handle/123456789/1453In: Gazzetta medica italiana - Archivio per le scienze mediche = A Journal on Internal Medicine and Pharmacology. Turin : Edizioni Minerva Medica, 2026. ISSN 0393-3660. Vol. 185, no. 1-2 (2026), pp. 27-31.BACKGROUND: The aim of this study was to assess whether the arm from which the blood sample was taken could potentially affect the results of the athlete’s biological passport (ABP) data. METHODS: The study involved 25 adult male athletes aged between 20 and 35 years old. The analysis took place in an accredited laboratory, where all participants had their blood collected in the morning after fasting from both the right and left arms. Regarding the evaluation, we focused on the parameters monitored in the ABP (hemoglobin, reticulocytes, Off-score). The sampling was carried out at 8:00 a.m. The parameters analyzed were those monitored in the athlete’s biological passport: hemoglobin and reticulocytes, from which the Off-score was derived (Off-score = Hgb × 10-60 × (√reticulocytes). RESULTS: The research results suggest that the sampling location - that is, from which arm the blood was sampled, may have a significant impact on the data interpreted in the ABP. CONCLUSIONS: Based on our findings, we recommend further research focused on investigating potential differences caused by the location of blood sampling. Future research should involve conducting similar measurements on a larger sample size of both athletes and non-athletes.enCC BY-NC Creative Commons Attribution-NonCommercial 4.0. Internationalinfo:eu-repo/semantics/openAccessramenášportovcisportsmenhemoglobínretikulocytyreticulocytesArticle