Relationship between vitamin D and TSH levels in obese individuals with hypertension

Obesity, hypertension (HT), and vitamin D deficiency are increasingly prevalent global health issues with significant clinical implications. Obesity, defined as a body mass index (BMI) of 30 or above, represents an excessive accumulation of adipose tissue that poses a serious health risk. Hypertension, characterized by a systolic blood pressure of ≥140 mmHg and/or a diastolic pressure of ≥90 mmHg, is a major risk factor for several life-threatening conditions including coronary artery disease, stroke, aneurysms, and renal failure. Vitamin D, a prohormone with endocrine, autocrine, and paracrine effects, plays a vital role not only in bone metabolism but also in various systemic processes. Its deficiency has been associated with a range of pathological conditions such as diabetes, metabolic syndrome, autoimmune disorders, cardiovascular diseases, HT, and cancer. In recent years, increasing attention has been directed toward the broader physiological roles of vitamin D. The thyroid gland, an endocrine organ regulated by thyroid-stimulating hormone (TSH), is responsible for synthesizing thyroid hormones that are critical for metabolic regulation. This retrospective study aimed to evaluate the levels of vitamin D and thyroid hormones, including T3, T4, and TSH, in obese individuals diagnosed with hypertension, with the goal of contributing to the understanding of the interactions among these variables. The study included 102 participants aged over 18 years with a BMI above 30 who were diagnosed with HT and presented to Sabuncuoğlu Şerefeddin Training and Research Hospital between 2020 and 2023. Subjects were divided into three groups: obese individuals with HT, obese individuals without HT, and non-obese individuals without HT. No statistically significant differences were observed among the groups in terms of vitamin D, T3, T4, or TSH levels (p > 0,05). However, a significant age difference was identified between the hypertensive and control groups (p <0,05). Correlation analysis revealed a weak but statistically significant positive relationship between vitamin D and T3 levels (p <0,05), as well as a moderate positive correlation between T3 and T4 (p <0,05). Regression analysis showed that gender had a significant negative effect on T3 levels (β = -0,278; p = 0,007), while T4 levels were negatively associated with TSH (β = -0,248; p = 0,015). No other significant associations were detected. The findings indicate that while HT prevalence increases with age and T3 levels tend to be lower in females, vitamin D and thyroid hormone levels do not exhibit significant associations with age or gender, nor is there a direct correlation between vitamin D status and thyroid function.