{
  "abstract": "Background/Objectives: Pre-admission levothyroxine use may influence the interpretation of thyroid tests beyond the conventional framework of non-thyroidal illness syndrome (NTIS). We examined whether thyroid hormone–outcome associations differed by treatment status. Methods: This retrospective study included medical inpatients with thyroid-stimulating hormone (TSH) < 5 mIU/L during 2006–2024. Propensity-score matching used age, sex, and 16 comorbidity indicators. Complete-case negative-binomial and logistic models examined hospitalization length and in-hospital mortality, with treatment-by-hormone interactions. Results: Among 14,332 matched patients, 3717 had complete data (1986 users; 1731 nonusers). Higher free triiodothyronine (FT3) in nonusers was associated with shorter hospitalization (incidence–rate ratio [IRR] 0.76, 95% confidence interval [CI] 0.73–0.80) and lower mortality odds (odds ratio [OR] 0.47, 95% CI 0.35–0.62). Free thyroxine (FT4) associations differed by levothyroxine use for both hospitalization length (interaction IRR 0.95, 95% CI 0.94–0.97) and mortality (interaction OR 0.83, 95% CI 0.77–0.90; both p < 0.001). At mean hormone concentrations, levothyroxine use was associated with shorter hospitalization (IRR 0.87, 95% CI 0.81–0.94) and lower mortality odds (OR 0.53, 95% CI 0.35–0.82). Crude mortality was 4.6% versus 5.0%, respectively; the conditional estimates represent a different comparison. Conclusions: FT4–outcome associations differed by pre-admission levothyroxine use, extending the established low-T3 prognostic framework to treatment-specific hormone patterns. These findings support considering treatment history when interpreting inpatient thyroid tests. Selective testing and residual confounding limit causal interpretation.",
  "abstract_shown": true,
  "affiliations": [
    "Institute of Endocrinology, Bnai Zion Medical Center, 47 Eliyahu Golomb Avenue, Haifa 3339419, Israel",
    "The Ruth and Bruce Rappaport Faculty of Medicine, Technion, Israel Institute of Technology, 1 Efron Street, Haifa 3339101, Israel",
    "Clinical Laboratories Division, Bnai Zion Medical Center, Haifa 3339419, Israel"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 8,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Mohammad Sheikh-Ahmad"
    },
    {
      "affs": [
        0
      ],
      "name": "Ilana Rosenblatt"
    },
    {
      "affs": [
        0
      ],
      "name": "Hadas Rabani"
    },
    {
      "affs": [
        2
      ],
      "name": "Clara Henig"
    },
    {
      "affs": [
        0
      ],
      "name": "Balsam Dakwar"
    },
    {
      "affs": [
        0
      ],
      "name": "Ekaterina Yovanovich"
    },
    {
      "affs": [
        0
      ],
      "name": "Emad Khoury"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Leonard Saiegh",
      "orcid": "0000-0001-5771-6569"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bkb1a1dtp9sva.bib",
  "cited_by": 0,
  "doi": "10.3390/jcm15218382",
  "fulltext_url": null,
  "id": "bkb1a1dtp9sva",
  "issns": [
    "2077-0383"
  ],
  "landing_url": "https://www.mdpi.com/2077-0383/15/21/8382",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2712|Thyroid Disorders and Treatments"
    ]
  ],
  "openalex": "W7224114053",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-28",
  "publisher": "MDPI AG",
  "ris": "https://research.draconitic.com/paper/bkb1a1dtp9sva.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:01Z",
      "native_id": "10.3390/jcm15218382",
      "source": "crossref",
      "url": "https://www.mdpi.com/2077-0383/15/21/8382"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2712|Thyroid Disorders and Treatments",
      "subfield": "endocrinology-metabolism"
    }
  ],
  "title": "Beyond Euthyroid Sick Syndrome: Pre-Admission Levothyroxine Use and Thyroid Hormone–Outcome Associations in Hospitalized Patients",
  "title_text": "Beyond Euthyroid Sick Syndrome: Pre-Admission Levothyroxine Use and Thyroid Hormone–Outcome Associations in Hospitalized Patients",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:20:01Z",
  "url": "https://research.draconitic.com/paper/bkb1a1dtp9sva",
  "venue": "Journal of Clinical Medicine",
  "versions": []
}