{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T16:53:50Z","timestamp":1790787230614,"version":"4.1.0"},"reference-count":69,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2025,6,27]],"date-time":"2025-06-27T00:00:00Z","timestamp":1750982400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diseases"],"abstract":"<jats:p>Background: Vitamin D is a steroid hormone, essential for the immune system and bone health. Since the sun is meant to provide at least 80% of daily vitamin D requirements, the COVID-19 pandemic is likely to have induced a considerable influence on calcium metabolism. Methods: We analyzed data from 1138 children, seen in an outpatient pediatric endocrinology clinic from 2022\u20132023. Vitamin D status was classified as deficiency if 25(OH)D \u2264 20 ng\/mL, insufficiency &lt; 30 ng\/mL, and sufficiency \u2265 30 ng\/mL. Results: Overall, 60.8% of children had vitamin D deficiency or insufficiency worsened with age (p &lt; 0.005), and with adolescent males having higher 25(OH)D concentrations than females (p &lt; 0.05). A negative correlation was found between 25(OH)D and BMI SDS (R2 = 0.02, p &lt; 0.001), and 25(OH)D concentrations varied seasonally, decreasing in winter. Subclinical hyperparathyroidism [parathyroid hormone (PTH) &gt; 45 pg\/mL) and normal calcium] was found in 21.5% of children, with 73.5% of them being vitamin D deficient or insufficient. A negative correlation between PTH and 25(OH)D was observed, with PTH plateauing at 25(OH)D above 40 ng\/mL (p &lt; 0.001). Conclusions: Compared to the pre-pandemic data (2016\u20132018), with only 5.1% of children having subclinical hyperparathyroidism (p &lt; 0.001), these findings suggest a marked deterioration in vitamin D status and calcium metabolism in children, with possible unforeseen consequences for bone, immune, and general health.<\/jats:p>","DOI":"10.3390\/diseases13070198","type":"journal-article","created":{"date-parts":[[2025,6,27]],"date-time":"2025-06-27T05:29:58Z","timestamp":1751002198000},"page":"198","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Dramatic Deterioration of Subclinical Hyperparathyroidism in Children and Adolescents During the Post-COVID-19 Period"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2754-9891","authenticated-orcid":false,"given":"Maria","family":"Loutsou","sequence":"first","affiliation":[{"name":"Department of Pediatrics, School of Medicine, University of Thessaly, General University Hospital of Larissa, Biopolis, 41110 Larissa, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eleni","family":"Dermitzaki","sequence":"additional","affiliation":[{"name":"Pediatric Endocrine Clinics, Athens Pediatric Center, Marousi, 15125 Athens, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2804-0859","authenticated-orcid":false,"given":"Rodis D.","family":"Paparodis","sequence":"additional","affiliation":[{"name":"Division of Endocrinology, Diabetes and Metabolism, Loyola University Medical Center, Maywood, IL 60153, USA"},{"name":"Hellenic Endocrine Network, Ermou 6 Str., 10563 Athens, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aspasia N.","family":"Michoula","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, School of Medicine, University of Thessaly, General University Hospital of Larissa, Biopolis, 41110 Larissa, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8901-7161","authenticated-orcid":false,"given":"Nicholas","family":"Angelopoulos","sequence":"additional","affiliation":[{"name":"Hellenic Endocrine Network, Ermou 6 Str., 10563 Athens, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4112-8396","authenticated-orcid":false,"given":"Panagiotis","family":"Christopoulos","sequence":"additional","affiliation":[{"name":"Second Department of Obstetrics and Gynecology, Medical School, \u201cAretaieion\u201d University Hospital, National and Kapodistrian University of Athens, 11527 Athens, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stavros","family":"Diamantopoulos","sequence":"additional","affiliation":[{"name":"Pediatric Endocrine Division, Iaso Children\u2019s Hospital, 11521 Athens, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1929-3275","authenticated-orcid":false,"given":"George","family":"Mastorakos","sequence":"additional","affiliation":[{"name":"Areteio Hospital, Medical School, National and Capodistrian University of Athens, 10674 Athens, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9221-5628","authenticated-orcid":false,"given":"Ioanna N.","family":"Grivea","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, School of Medicine, University of Thessaly, General University Hospital of Larissa, Biopolis, 41110 Larissa, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6083-3560","authenticated-orcid":false,"given":"Dimitrios T.","family":"Papadimitriou","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, School of Medicine, University of Thessaly, General University Hospital of Larissa, Biopolis, 41110 Larissa, Greece"},{"name":"Pediatric Endocrine Clinics, Athens Pediatric Center, Marousi, 15125 Athens, Greece"},{"name":"Hellenic Endocrine Network, Ermou 6 Str., 10563 Athens, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,6,27]]},"reference":[{"key":"ref_1","first-page":"913","article-title":"Analysis of Vitamin D Status in Men Highly Exposed to Sunlight","volume":"28","author":"Zhang","year":"2015","journal-title":"Biomed. 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