Serum Vitamin D and Osteocalcin for Assessment of Bone Mineral Metabolism: A Comparison of Children with Steroid-Sensitive and Resistant Nephrotic Syndrome

Abstract

Background Long-term corticosteroid use decreases osteoblastic activity and bone matrix formation. Osteocalcin (OC), a marker of bone turnover, is more sensitive than alkaline phosphatase in indicating bone matrix synthesis. Materials and Methods The cross-sectional study was done from January to September 2021; a total of 62 (40 males, 22 females) children (2–18 years) with nephrotic syndrome in disease remission were enrolled. Thirty-two had steroid-sensitive nephrotic syndrome (SSNS), and 30 had steroid-resistant nephrotic syndrome (SRNS). Children who had received daily steroids or high doses of vitamin D within the previous three months were excluded. The primary objective of this study was to assess bone mineral metabolism by measuring vitamin D, parathyroid hormone (PTH), and osteocalcin levels. Results In children with SSNS, 46.8% had vitamin D insufficiency, 21.9% vitamin D deficiency, and median vitamin D levels were 28.4 ng/mL; in the SRNS group, 40% had insufficiency, 33.4% deficiency, and vitamin D levels were 26.6 ng/mL. The median steroid dose used in the previous 6 months was significantly higher in the SRNS patients, 0.63 (0.35, 0.77) mg/kg on alternate days compared to SSNS, 0.50 (0.32, 0.60) mg/kg (p = 0.02). Median serum OC levels were lower in SRNS 20.4 (10.8, 33.5) ng/mL compared to SSNS, 35.6 (22.5, 42.7) ng/mL (p = 0.004). Conclusion Bone metabolism is negatively affected in children with nephrotic syndrome, especially in those with SRNS and must continue to be vitamin D insufficient despite routine supplementation; serum OC appears to be a promising marker for this evaluation.