Role of Parathyroid Hormone in Determination of Fat Mass in Patients with Vitamin D Deficiency

Obesity has become a global epidemic and it is rising is Asia. Vitamin D deficiency (VDD) is widely prevalent in the Indian subcontinent. Studies have linked VDD to obesity and shown correlation between parathyroid hormone (PTH), 25-hydroxy Vitamin D (25(OH)D), and fat mass (FM). However, studies on the role of PTH among subjects with VDD are lacking. The objective of this study is to study the role of PTH in the determination of FM in participants with VDD. Five hundred and fifty-one adults (m:247, f:304) were included in this study. Total and regional (trunk, arm, and leg) FM was assessed by dual X-ray absorptometry. Biochemical and hormonal parameters such as calcium, phosphorus, alkaline phosphatase, ionic calcium, 25(OH)D, and PTH were also analyzed. The mean age of the study population was 58.8 ± 15.8 years (Male: [63.3 ± 13.1], Female: [55.2 ± 16.9]). FM and body mass index were significantly lower in females with higher levels of serum 25(OH)D. Total FM was negatively correlated with serum 25(OH)D ( = -0.363, < 0.0001) and positively correlated with serum PTH (r: 0.262, < 0.0001) in females only. Females with VDD and secondary hyperparathyroidism had higher FM than those with normal PTH. Females with VDD had higher total and regional FM. However, this correlation was evident only in those with high serum PTH levels, suggesting a potential role of PTH in the accumulation of FM.