Department of Pediatrics, Lady Hardinge Medical College and Kalawati Saran Children's Hospital, New Delhi, India.
Department of Pediatrics, Lady Hardinge Medical College and Kalawati Saran Children's Hospital, New Delhi, India Correspondence to: Dr. Abhijeet Saha, Professor, Department of Pediatrics, Lady Hardinge Medical College and associated Kalawati Children's Hospital, New Delhi, India.
Indian Pediatr. 2024 Oct 15;61(10):941-946. Epub 2024 Jul 23.
To estimate the levels of serum bioavailable vitamin D in children presenting with first episode nephrotic syndrome (FENS) at diagnosis and after 4 weeks of standard steroid therapy while the child is in remission, and compare the same with age-sex matched healthy controls.
We included children aged 1 month to 12 years presenting as FENS and estimated the serum calcium, phosphorus, alkaline phosphatase, 25-hydroxy vitamin D [25(OH)D], parathormone, serum and urine vitamin D binding protein (VDBP) at diagnosis and after 4 weeks of standard steroid therapy while the child is in remission. We also included age-sex matched healthy controls for comparison. Bioavailable and free 25(OH)D were estimated at enrolment and at 4 weeks of therapy.
The mean (SD) 25(OH)D level (ng/mL) in children with FENS was 11.3 (6.1) at diagnosis and 13.6 (6.2) at 4 weeks follow-up, while the observed value in healthy controls was 16 (7) ng/mL. The median (IQR) serum VDBP level in FENS at enrolment was 223.0 (144, 305.5) µg/mL. There was significant correlation between serum VDBP and serum albumin levels (P = 0.04). At 4 weeks (remission), the median (IQR) VDBP levels increased to 554.5 (383, 644.75) µg/mL (P < 0.001). The median (IQR) free 25(OH)D levels (pg/mL) in children with FENS was 1.07 (0.8, 1.6) at enrolment and 0.53 (0.37, 0.86) at 4 weeks follow-up. The median (IQR) bioavailable vitamin D in FENS during proteinuria was 0.58 (0.4, 0.83) ng/ml, much lower as compared to controls 0.97 (0.85, 1.08) ng/mL (P < 0.001). On follow-up at 4 weeks of remission the median (IQR) bioavailable vitamin D levels increased to 0.87 (0.59, 1.42) ng/mL (P = 0.015). There was a very strong positive correlation between free vitamin D and bioavailable vitamin D (r = 0.9, P < 0.001); a strong negative correlation between serum VDBP and bioavailable vitamin D (r = - 0.69, P < 0.001). There was a positive correlation between 25 (OH)D and bioavailable vitamin D (r = 0.63, P < 0.001). Serum VDBP and serum albumin showed statistically significant positive correlation (r = 0.37, P < 0.05).
Children with FENS are deficient in vitamin D. The free and bioavailable vitamin D levels are reduced in children with FENS during the proteinuric phase. Further studies to assess the association between bioavailable vitamin D and 25(OH)D with bone mineral density are needed in children with nephrotic syndrome to validate the utility of bioavailable vitamin D in clinical practice.
评估初发肾病综合征（FENS）患儿在诊断时及标准类固醇治疗 4 周后缓解期的血清生物可利用维生素 D 水平，并与年龄性别匹配的健康对照组进行比较。
我们纳入了年龄在 1 个月至 12 岁之间的初发肾病综合征患儿，并在诊断时和标准类固醇治疗 4 周后缓解期时评估血清钙、磷、碱性磷酸酶、25-羟维生素 D [25(OH)D]、甲状旁腺激素、血清和尿维生素 D 结合蛋白（VDBP）。我们还纳入了年龄性别匹配的健康对照组进行比较。在入组时和治疗 4 周时评估生物可利用和游离 25(OH)D。
FENS 患儿的平均（SD）25(OH)D 水平（ng/mL）在诊断时为 11.3（6.1），在 4 周随访时为 13.6（6.2），而健康对照组的观察值为 16（7）ng/mL。FENS 患儿在入组时的血清 VDBP 中位数（IQR）为 223.0（144，305.5）µg/mL。血清 VDBP 与血清白蛋白水平之间存在显著相关性（P = 0.04）。在 4 周（缓解期）时，VDBP 中位数（IQR）水平升高至 554.5（383，644.75）µg/mL（P<0.001）。FENS 患儿的游离 25(OH)D 中位数（IQR）水平在入组时为 1.07（0.8，1.6）pg/mL，在 4 周随访时为 0.53（0.37，0.86）pg/mL。FENS 患儿在蛋白尿期间的生物可利用维生素 D 中位数（IQR）为 0.58（0.4，0.83）ng/ml，远低于对照组的 0.97（0.85，1.08）ng/mL（P<0.001）。在缓解期 4 周随访时，生物可利用维生素 D 中位数（IQR）水平升高至 0.87（0.59，1.42）ng/mL（P=0.015）。游离维生素 D 和生物可利用维生素 D 之间存在很强的正相关（r=0.9，P<0.001）；血清 VDBP 和生物可利用维生素 D 之间存在很强的负相关（r=-0.69，P<0.001）。25(OH)D 与生物可利用维生素 D 之间存在正相关（r=0.63，P<0.001）。血清 VDBP 和血清白蛋白之间存在统计学显著的正相关（r=0.37，P<0.05）。
FENS 患儿维生素 D 缺乏。在 FENS 患儿蛋白尿期，游离和生物可利用维生素 D 水平降低。需要进一步研究评估生物可利用维生素 D 与 25(OH)D 与骨矿物质密度之间的关联，以验证生物可利用维生素 D 在肾病综合征患儿中的临床应用价值。
