Abstract: diagnostics Article Association of Vitamin D Deficiency and Insufficiency with Pathology in Hospitalized Patients Sandica Bucurica 1,2 , Ioana Prodan 1 , Mihaela Pavalean 1 , Corina Taubner 3 , Ana Bucurica 1 , Calin Socol 1 , Roxana Calin 4 , Florentina Ionita-Radu 1,2, * and Mariana Jinga 1,2 1 2 3 4 * Citation: Bucurica, S.; Prodan, I.; Department of Gastroenterology, “Carol Davila” University of Medicine and Pharmacy Bucharest, 020021 Bucharest, Romania Department of Gastroenterology, “Carol Davila” University Central Emergency Military Hospital, 010825 Bucharest, Romania Medical Analysis Laboratory, “Carol Davila” University Central Emergency Military Hospital, 010825 Bucharest, Romania Department of Gastroenterology, Pucioasa City Hospital, 135400 Pucioasa, Romania Correspondence: fionita04@yahoo.com Abstract: Vitamin D deficiency is one of the most common medical conditions, with approximately one billion people having low vitamin D levels. Vitamin D is associated with a pleiotropic effect (immunomodulatory, anti-inflammatory and antiviral), which can be essential for a better immune response. The aim of this research was to evaluate the prevalence of vitamin D deficiency/insufficiency in hospitalized patients focusing on demographic parameters as well as assessing the possibility of its associations with different comorbidities. Of 11,182 Romanian patients evaluated in the study over 2 years, 28.83% had vitamin D deficiency, 32.11% insufficiency and 39.05% had optimal vitamin D levels. The vitamin D deficiency was associated with cardiovascular disorders, malignancies, dysmetabolic disorders and SARS-CoV2 infection, older age and the male sex. Vitamin D deficiency was prevalent and showed pathology association, while insufficiency of vitamin D (20–30 ng/mL) had lower statistical relevance and represents a grey zone in vitamin D status. Guidelines and recommendations are necessary for homogeneity of the monitoring and management of inadequately vitamin D status in the risk categories. Pavalean, M.; Taubner, C.; Bucurica, A.; Socol, C.; Calin, R.; Ionita-Radu, F.; Jinga, M. Association Keywords: vitamin D deficiency; hospitalized; 25(OH)D; Romania of Vitamin D Deficiency and Insufficiency with Pathology in Hospitalized Patients. Diagnostics 2023, 13, 998. https://doi.org/ 10.3390/diagnostics13050998 Academic Editor: Giulia Bivona Received: 31 January 2023 Revised: 23 February 2023 Accepted: 3 March 2023 Published: 6 March 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).