Deficiency of Vitamin D in Patients with Hypothyroidism and as a Related Risk Factor for Cardiovascular Disease

Hypothyroidism is a common health condition caused by a deficiency of the thyroxine hormone. The thyroxine hormone regulates the body's metabolic functions, and its deficiency can result in complications across various organs. Vitamin D deficiency is a worldwide concern that has health implications; it is regarded as a pandemic. It represents a global health concern primarily stemming from insufficient sunlight exposure. Hypothyroidism has been demonstrated to adversely affect the cardiovascular system, leading to issues such as vascular endothelial dysfunction, elevated systemic vascular resistance, dyslipidemia, and early-onset atherosclerosis beyond the typical symptoms. Objectives: To examine the frequency of vitamin D insufficiency in individuals with hypothyroidism and assess its possible function as an independent or contributing risk factor for cardiovascular ailments. A cross-sectional study was conducted at Azadi teaching hospital between February 2026 and October 2026.Methedology: A cohort of 90 participants aged between 25 and 65 was assembled and classified into two groups: hypothyroidism group and control group. Venous blood samples were collected after an overnight fast lasting 8 to 12 hours. The following biomarkers were evaluated: Serum TSH and FT4, Serum 25(OH)D concentrations, Fasting Lipid Panel (Total Cholesterol [TC], Low-Density Lipoprotein [LDL-C], High-Density Lipoprotein [HDL-C], Triglycerides [TG], and High-Sensitivity C-Reactive Protein [hs-CRP]). The data analysis was performed using SPSS Version 26.0. Continuous variables were expressed as Mean ± Standard Deviation (SD). Results: Serum 25(OH)D concentrations were significantly lower in patients with hypothyroidism than in healthy subjects. The hypothyroidism group showed a significantly higher prevalence of dyslipidemia and increased inflammatory markers. Pearson correlation assessment showed a statistically significant negative link between blood 25(OH)D and TSH (r = -0.42, p < 0.001, and between 25(OH)D and LDL-C (r = -0.38, p = 0.002). Conclusion: Vitamin D insufficiency was shown to be quite common in primary hypothyroidism patients and was substantially linked with more severe dyslipidemia and elevated inflammatory markers (hs-CRP). These accumulated factors greatly increase the risk for subsequent cardiovascular diseases.