Introduction: Mineral and bone disorders are common in patients with chronic kidney disease (CKD). Vitamin D plays an important role in calcium-phosphorus balance.
Objectives: The main aim of this investigation is to assess the relation between circulating levels of 25(OH) vitamin D and parathyroid hormone (PTH) and estimating the best threshold of vitamin D which may prevent secondary hyperparathyroidism.
Patients and Methods: This cross-sectional study was conducted between January 2014 to September 2015. Adult patients with CKD who were not on routine peritoneal dialysis or hemodialysis and did not receive any kidney transplantation, enrolled to this study. Patients who were pregnant or who were on vitamin D supplementation therapy were excluded. Basic demographic and laboratory information were measured.
Results: Around 254 patient enrolled in this study (55.1% men). The prevalence of vitamin D deficiency and insufficiency were significantly high, 12.6% and 53.9%, respectively. Serum PTH level increased significantly as circulating plasma level of 25(OH) vitamin D decreased (P = 0.003). Serum total calcium increased significantly with high levels of plasma 25(OH) vitamin D (P < 0.001) and hypercalcemia was seen in 2.8% of patients. Piecewise linear regression modeling of PTH for 25(OH) vitamin D estimated the best threshold for 25(OH) vitamin D of 13.00 ng/mL (95% CI: 2.55-23.44 ng/mL) (P = 0.015).
Conclusion: This study again confirms this fact that sufficient level of serum 25(OH) vitamin D is mandatory in patients with CKD in order to prevent secondary hyperparathyroidism. Although this study recommends level of serum 25(OH) vitamin D to be above 13 ng/mL for this purpose.