{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T08:05:07Z","timestamp":1784880307786,"version":"3.55.0"},"reference-count":32,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T00:00:00Z","timestamp":1784678400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Pathogens"],"abstract":"<jats:p>Hepatitis B surface antigen (HBsAg) signal-to-cutoff (S\/CO) values and isolated anti-HBc positivity represent two significant diagnostic challenges in hepatitis B virus (HBV) serology. This retrospective study, conducted in Karabuk between 2021 and 2025, aimed to evaluate the correlation between these profiles and HBV DNA positivity to determine the optimal S\/CO thresholds for confirmatory testing and clarify the clinical relevance of isolated anti-HBc reactivity. Among 17,356 patients screened for anti-HBc, isolated anti-HBc positivity was identified in 506 patients (2.9%), of whom 3.2% had detectable HBV DNA. Positivity was significantly higher in patients older than 50 years and in the Gastroenterology department. Separately, 213 specimens with HBsAg S\/CO values between 1.0 and 10.0 underwent HBV DNA confirmation testing. ROC analysis yielded an excellent area under the curve of 0.937, with an S\/CO threshold of \u22653.04, achieving 100% sensitivity for HBV DNA detection. All specimens with S\/CO values between 1.0 and 3.0 were HBV DNA-negative. In this study population, no serum HBV DNA positivity was detected among samples with S\/CO values below 3.04, suggesting that HBV DNA testing may help avoid unnecessary confirmatory work-up in this range. Anti-HBc screening should be prioritized in older patients. S\/CO-based confirmatory algorithm using HBV DNA testing may improve diagnostic accuracy and reduce unnecessary clinical interventions in routine hepatitis B screening programs.<\/jats:p>","DOI":"10.3390\/pathogens15070777","type":"journal-article","created":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T13:25:46Z","timestamp":1784726746000},"page":"777","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Two Diagnostic Challenges in Hepatitis B Serology: Low HBsAg S\/CO Values and Isolated Anti-HBc Positivity"],"prefix":"10.3390","volume":"15","author":[{"given":"\u015eerife","family":"Y\u0131lmaz G\u00fcrb\u00fcz","sequence":"first","affiliation":[{"name":"Department of Medical Microbiology, Medical Faculty, Karabuk University, 78050 Karabuk, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-1565-5223","authenticated-orcid":false,"given":"O\u011fuzhan","family":"Ya\u011fd\u0131","sequence":"additional","affiliation":[{"name":"Medical Microbiology Laboratory, Karabuk Training and Research Hospital, 78100 Karabuk, Turkey"},{"name":"Medical Microbiology Laboratory, \u00c7orlu State Hospital, 59850 Tekirda\u011f, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Erhan","family":"Ba\u015far","sequence":"additional","affiliation":[{"name":"Medical Microbiology Laboratory, Karabuk Training and Research Hospital, 78100 Karabuk, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"385","DOI":"10.3138\/canlivj-2024-0014","article-title":"Canadian Association for the Study of the Liver Single Topic Conference on Hepatitis B Virus: \u2018Progress toward hepatitis B elimination in Canada\u2019","volume":"7","author":"Hercun","year":"2024","journal-title":"Can. Liver J."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Ali, H., Buenning, C., and Daghfal, D. (2025). Advancing HBV Diagnostics: The Role of Ultrasensitive HBsAg Testing. Diagnostics, 15.","DOI":"10.20944\/preprints202510.0021.v1"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1","DOI":"10.15585\/mmwr.rr7201a1","article-title":"Screening and Testing for Hepatitis B Virus Infection: CDC Recommendations\u2014United States, 2023","volume":"72","author":"Conners","year":"2023","journal-title":"MMWR Recomm. Rep."},{"key":"ref_4","first-page":"65","article-title":"Evaluation of HBsAg Seroclearance in Patients with Hepatitis B","volume":"12","year":"2022","journal-title":"Euroasian J. Hepatogastroenterol."},{"key":"ref_5","first-page":"10","article-title":"Current Status on the Epidemiology of Hepatitis B Virus Infection in \u0130stanbul","volume":"14","author":"Karabey","year":"2025","journal-title":"Mediterr. J. Infect. Microb. Antimicrob."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2238","DOI":"10.1128\/JCM.00324-13","article-title":"Highly Sensitive Detection of Hepatitis B Virus Surface Antigen by Use of a Semiautomated Immune Complex Transfer Chemiluminescence Enzyme Immunoassay","volume":"51","author":"Takeda","year":"2013","journal-title":"J. Clin. Microbiol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1016\/j.jiac.2023.09.007","article-title":"Efficient Implementation of Hepatitis B Surface Antigen Confirmatory Neutralization Tests","volume":"30","author":"Yonezawa","year":"2024","journal-title":"J. Infect. Chemother."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"485","DOI":"10.1093\/labmed\/lmab006","article-title":"Need for Confirmatory Neutralization Tests for Hepatitis B Surface Antigen Tests in Populations with Intermediate Prevalence","volume":"52","author":"Lee","year":"2021","journal-title":"Lab. Med."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Rysgaard, C.D., Morris, C.S., Drees, D., Bebber, T., Davis, S.R., Kulhavy, J., and Krasowski, M.D. (2012). Positive Hepatitis B Surface Antigen Tests Due to Recent Vaccination: A Persistent Problem. BMC Clin. Pathol., 12.","DOI":"10.1186\/1472-6890-12-15"},{"key":"ref_10","first-page":"6","article-title":"Combined HBsAg and Anti-HBc Testing Is Required to Estimate Hepatitis B Virus Seroprevalence in a Low-Endemic Country: Findings from a Nationwide Population-Based Serosurvey, Belgium, 2020","volume":"31","author":"Ho","year":"2026","journal-title":"Eurosurveillance"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"693","DOI":"10.1038\/s41598-023-50907-6","article-title":"Prevalence and Influential Factors of Isolated Hepatitis B Core Antibody Positivity in a Chinese Adult Population","volume":"14","author":"Wang","year":"2024","journal-title":"Sci. Rep."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Hyun, C.S., Lee, S., and Ventura, W.R. (2019). The Prevalence and Significance of Isolated Hepatitis B Core Antibody (Anti-HBc) in Endemic Population. BMC Res. Notes, 12.","DOI":"10.1186\/s13104-019-4287-z"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Saitta, C., Pollicino, T., and Raimondo, G. (2022). Occult Hepatitis B Virus Infection: An Update. Viruses, 14.","DOI":"10.3390\/v14071504"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Yano, Y., Sato, I., Imanishi, T., Yoshida, R., Matsuura, T., Ueda, Y., and Kodama, Y. (2024). Clinical Significance and Remaining Issues of Anti-HBc Antibody and HBV Core-Related Antigen. Diagnostics, 14.","DOI":"10.20944\/preprints202402.0759.v1"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"8","DOI":"10.7754\/Clin.Lab.2025.241219","article-title":"Determination of a Positive Predictive Value for Confirming HBsAg Qualitative II on Architect and Alinity i (Abbott Diagnostics)","volume":"71","author":"Zahi","year":"2025","journal-title":"Clin. Lab."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"475","DOI":"10.1093\/labmed\/lmac021","article-title":"Cutoff Value of Qualitative HBsAg for Confirmatory HBsAg Using the Chemiluminescence Microparticle Immunoassay Method","volume":"53","author":"Pasaribu","year":"2022","journal-title":"Lab. Med."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"e0554","DOI":"10.1097\/HC9.0000000000000554","article-title":"A Need for Confirmatory Testing of Isolated HBcAb-Positive Results in Screening Programs","volume":"8","author":"Fu","year":"2024","journal-title":"Hepatol. Commun."},{"key":"ref_18","first-page":"263","article-title":"Retrospective Evaluation of Isolated Hepatitis B Core Antibody (Isolated Anti-HBc) Positivity in Patients with Different Clinical Complaints","volume":"51","author":"Cihan","year":"2021","journal-title":"Turk. Mikrobiyol. Cemiy. Derg."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Moretto, F., Catherine, F.X., Esteve, C., Blot, M., and Piroth, L. (2020). Isolated Anti-HBc: Significance and Management. J. Clin. Med., 9.","DOI":"10.3390\/jcm9010202"},{"key":"ref_20","first-page":"e154441","article-title":"Evaluation of Isolated Anti-HBc Positivity in Patients Considered for Hepatitis B Diagnosis: 8.5 Years of Data","volume":"17","year":"2024","journal-title":"Jundishapur J. Microbiol."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Mikelet Boussoukou, I.P., Andeme Eyi, A.S., Ondh-Obame, J.A., Ondamba, P.J.N., Magossou Mbadinga, M.J., Makoyo Komba, O., Omouessi, S.T., Djoba Siawaya, J.F., and Ndeboko, B. (2026). Molecular Characterization of Atypical Hepatitis B Serological Profiles in HBsAg-Negative Women of Childbearing Age in Gabon. Curr. Issues Mol. Biol., 48.","DOI":"10.3390\/cimb48020184"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1759720X20912646","DOI":"10.1177\/1759720X20912646","article-title":"Reactivation of Hepatitis B Virus Infection in Rheumatic Diseases: Risk and Management Considerations","volume":"12","author":"Koutsianas","year":"2020","journal-title":"Ther. Adv. Musculoskelet. Dis."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Tsai, Y.-F., Hsu, C.-M., and Hsiao, H.-H. (2021). Management of Hepatitis B Virus Reactivation in Malignant Lymphoma Prior to Immunosuppressive Treatment. J. Pers. Med., 11.","DOI":"10.3390\/jpm11040267"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Elharabi, Z., Saba, J., and Akin, H. (2025). Navigating the Latest Hepatitis B Virus Reactivation Guidelines. Diseases, 13.","DOI":"10.3390\/diseases13110355"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"212","DOI":"10.7861\/clinmedicine.18-3-212","article-title":"Hepatitis B Virus Reactivation in Patients Treated with Immunosuppressive Drugs: A Practical Guide for Clinicians","volume":"18","author":"Koffas","year":"2018","journal-title":"Clin. Med."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"e29385","DOI":"10.1002\/jmv.29385","article-title":"High-Speed Centrifugation Rather than Lipoclear Reagent Can Be Used for Removing the Interference of Lipemia on Serological Tests of Infectious Diseases: AIDS, Hepatitis B, Hepatitis C, and Syphilis by Chemiluminescent Microparticle Immunoassay","volume":"96","author":"Liu","year":"2024","journal-title":"J. Med. Virol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"342","DOI":"10.4103\/ajts.ajts_42_24","article-title":"A False Reactive Hepatitis B Surface Antigen Result Due to Dislodged Gel from Vacutainer","volume":"19","author":"Sawant","year":"2025","journal-title":"Asian J. Transfus. Sci."},{"key":"ref_28","first-page":"2","article-title":"Determination of Initial HBsAg Cutoff Index Threshold for Reporting HBsAg Reactivity","volume":"68","author":"Wongchampa","year":"2024","journal-title":"Chula Med. J."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"251","DOI":"10.24293\/ijcpml.v24i3.1335","article-title":"Determination of Reactive HBsAg Cut-Off That Need Confirmatory Test","volume":"24","author":"Purnamawaty","year":"2018","journal-title":"Indones. J. Clin. Pathol. Med. Lab."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"5619","DOI":"10.2147\/JIR.S337561","article-title":"Alteration of the Immune Microenvironment in HBsAg and HBeAg Dual-Positive Pregnant Women Presenting a High HBV Viral Load","volume":"14","author":"Gao","year":"2021","journal-title":"J. Inflamm. Res."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"708","DOI":"10.1002\/cbin.10608","article-title":"HBxAg Suppresses Apoptosis of Human Placental Trophoblastic Cell Lines via Activation of the PI3 K\/Akt Pathway","volume":"40","author":"Wang","year":"2016","journal-title":"Cell Biol. Int."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1211","DOI":"10.3892\/etm.2021.10645","article-title":"HBxAg Promotes HBV Replication and EGFR Activation in Human Placental Trophoblasts","volume":"22","author":"Lin","year":"2021","journal-title":"Exp. Ther. Med."}],"container-title":["Pathogens"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-0817\/15\/7\/777\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T07:51:19Z","timestamp":1784879479000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-0817\/15\/7\/777"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,22]]},"references-count":32,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["pathogens15070777"],"URL":"https:\/\/doi.org\/10.3390\/pathogens15070777","relation":{},"ISSN":["2076-0817"],"issn-type":[{"value":"2076-0817","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,22]]}}}