{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T17:01:31Z","timestamp":1781715691519,"version":"3.54.5"},"reference-count":46,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T00:00:00Z","timestamp":1781654400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Clinics and Practice"],"abstract":"<jats:p>Background: Post-thyroxine treatment of thyroid dysfunction remains a clinical concern, especially in Middle Eastern populations. Methods: This descriptive cross-sectional study was conducted in 2023 at King Fahad Hospital, Hufof, Kingdom of Saudi Arabia. Of the 237 patients treated with L-thyroxine (L-T4) for hypothyroidism, 163 patients, almost exclusively females (152 females, 11 males), met the inclusion criteria and were enrolled. Thyroid hormones, lipid profiles, and 25-hydroxyvitamin D (25OH-D) were measured using standard laboratory assays. Results: Only 57% of patients achieved euthyroid status following L-T4 treatment, while 12.3% developed post-thyroxine-treatment (PTT) hyperthyroidism, and 30.7% developed PTT hypothyroidism. Older age was significantly associated with dysthyroidism (p = 0.018), whereas obesity (p = 0.937) and vitamin D levels (p = 0.982) were not. Total cholesterol (TC) and LDLc positively correlated with TSH levels, while elevated triglycerides (TGs) were significantly associated with PTT hyperthyroidism. The two dysthyroid subgroups were comparable across all non-thyroid parameters, including age, BMI, 25(OH)D levels, and lipid fractions. However, free T4 was significantly higher in PTT hyperthyroidism (p &lt; 0.001); free T3 showed a trend toward higher levels in PTT hyperthyroidism (p = 0.052); and TSH was significantly higher in PTT hypothyroidism (p &lt; 0.001). Conclusions: The proportions of patients with PTT hypo- and hyperthyroidism are aligned with international observations. Furthermore, the age was significantly associated with dysthyroidism, and dyslipidemia is the most consistent biochemical correlate of suboptimal thyroid status; however, the associations of PTT dysthyroidism with hypovitaminosis D and BMI were not noticed in this setting.<\/jats:p>","DOI":"10.3390\/clinpract16060116","type":"journal-article","created":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T15:11:22Z","timestamp":1781709082000},"page":"116","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Post-Levothyroxine Thyroid Dysfunction in Saudi Arabian Patients with Hypothyroidism: A Cross-Sectional Study"],"prefix":"10.3390","volume":"16","author":[{"given":"Baraah Ghssan","family":"AlHassan","sequence":"first","affiliation":[{"name":"Department of Biomedical Sciences, College of Medicine, King Faisal University, Al-Ahsa P.O. Box 400, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6559-9742","authenticated-orcid":false,"given":"Maujid Masood","family":"Malik","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences, College of Medicine, King Faisal University, Al-Ahsa P.O. Box 400, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ahmed","family":"Mohamedain","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences, College of Medicine, King Faisal University, Al-Ahsa P.O. Box 400, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-6819-4688","authenticated-orcid":false,"given":"Adnan","family":"Jehangir","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences, College of Medicine, King Faisal University, Al-Ahsa P.O. Box 400, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Farhana","family":"Ayub","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences, College of Medicine, King Faisal University, Al-Ahsa P.O. Box 400, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1435-3774","authenticated-orcid":false,"given":"Omer","family":"Musa","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences, College of Medicine, King Faisal University, Al-Ahsa P.O. Box 400, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6516-5450","authenticated-orcid":false,"given":"Ahmed","family":"Ibrahim","sequence":"additional","affiliation":[{"name":"Department of Public Health, College of Applied Medical Sciences, King Faisal University, Al-Ahsa 31982, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8751-495X","authenticated-orcid":false,"given":"Habib Ahmad","family":"Qureshi","sequence":"additional","affiliation":[{"name":"Mohammed Al-Mana College for Medical Sciences, Al Khobar 34222, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hayder A.","family":"Giha","sequence":"additional","affiliation":[{"name":"Centre for Cardiovascular Science, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1111\/j.1365-2265.1995.tb01894.x","article-title":"The incidence of thyroid disorders in the community: A twenty-year follow-up of the Whickham Survey","volume":"43","author":"Vanderpump","year":"1995","journal-title":"Clin. 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