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

Background: 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.

Objective: The objective of this study is to study the role of PTH in the determination of FM in participants with VDD.

Subjects: Five hundred and fifty-one adults (m:247, f:304) were included in this study.

Materials and Methods: 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.

Results: 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 ( r = -0.363, P < 0.0001) and positively correlated with serum PTH (r: 0.262, P < 0.0001) in females only. Females with VDD and secondary hyperparathyroidism had higher FM than those with normal PTH.

Conclusions: 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.