Calcium, Vitamin D, and Bone Derangement in Nephrotic Syndrome

Samantha Peiling Yang; Lizhen Ong; Tze Ping Loh; Horng Ruey Chua; Cassandra Tham; Khoo Chin Meng; Lim Pin

doi:10.15605/jafes.036.01.12

Calcium, Vitamin D, and Bone Derangement in Nephrotic Syndrome

J ASEAN Fed Endocr Soc. 2021;36(1):50-55. doi: 10.15605/jafes.036.01.12. Epub 2021 May 3.

Authors

Samantha Peiling Yang^{1

2}, Lizhen Ong³, Tze Ping Loh³, Horng Ruey Chua⁴, Cassandra Tham², Khoo Chin Meng^{1

2}, Lim Pin^{1

2}

Affiliations

¹ Endocrinology Division, Department of Medicine, National University Hospital, Singapore.
² Endocrinology Division, Yong Loo Lin School of Medicine, Singapore.
³ Department of Laboratory Medicine, National University Hospital, Singapore.
⁴ Nephrology Division, Department of Medicine, National University Hospital, Singapore.

Abstract

Introduction: Derangement in calcium homeostasis is common in nephrotic syndrome (NS). It is postulated that low serum total calcium and vitamin D levels are due to loss of protein-bound calcium and vitamin D. It is unclear if free calcium and free vitamin D levels are truly low. The guideline is lacking with regards to calcium and vitamin D supplementation in NS. This study aims to examine calcium and vitamin D homeostasis and bone turnover in NS to guide practice in calcium and vitamin D levels supplementation.

Methodology: This is a prospective pilot study of ten patients diagnosed with NS, and eight healthy controls. Calcium, vitamin D, and bone turnover-related analytes were assessed at baseline, partial and complete remission in NS patients and in healthy controls.

Results: NS patients had low free and total serum calcium, low total 25(OH)D, normal total 1,25(OH)D levels and lack of parathyroid hormone response. With remission of disease, serum calcium and vitamin D metabolites improved. However, nephrotic patients who do not attain complete disease remission continue to have low 25(OH)D level.

Conclusion: In this study, the vitamin D and calcium derangement observed at nephrotic syndrome presentation trended towards normalisation in remission. This suggested calcium and vitamin D replacement may not be indicated in early-phase nephrotic syndrome but may be considered in prolonged nephrotic syndrome.

Keywords: Vitamin D deficiency; bone loss; hypocalcaemia; immune-mediated nephrotic syndrome.