Is it correct to supplement patients with nephrotic syndrome with vitamin D and calcium?

Vitamin D status and bone density in steroid-treated children with glomerulopathies: effect of cholecalciferol and calcium supplementation

PURPOSE

The aim of this study was to assess vitamin D status and bone density in steroid-treated children with glomerulopathies and to evaluate the effect of prophylactic vitamin D and calcium supplementation.

MATERIAL AND METHODS

Retrospective analysis was performed on 55 children aged 4-18 yrs with glomerulopathies. The following data were analyzed: antropometrical parameters, bone densitometries, parathormone, 25-hydroxyvitamin D (25-OHD), urinary calcium excretion and medications received for prevention of low bone mass.

RESULTS

A significant number of children (38%) had decreased spinal bone mineral density (BMD z-score < -2.0) and the majority of them (89%) had hypovitaminosis D (25-OHD < 30 ng/ml), 75% were vitamin D insufficient (25-OHD < 20 ng/ml) and 16% were vitamin D deficient (25-OHD < 10 ng/ml). The mean serum 25-OHD concentration was comparable to that of controls (19.32 ± 12.87 vs. 15.05 ± 8.52 ng/ml). Nearly all patients (82%) were receiving preparations of calcium and/or vitamin D to improve bone health. Patients on cholecalciferol had higher mean concentration of 25-OHD compared to those who were not receiving it (p=0.027) and to the controls (p=0.047). In 23 children on vitamin D and calcium supplementation for an average 6-month time, we observed an increase in the mean BMD values (p=0.004), however, mean BMD z-score and 25-OHD concentrations did not significantly change over time.

CONCLUSIONS

Vitamin D and bone density deficits are remarkably common in steroid-treated children with glomerulopathies, despite vitamin D and calcium repletion. In order to enhance the effectiveness of vitamin D supplementation for improvement of bone density, we suggest regular assessment of serum concentration of 25-OHD that can guide subsequent dose adjustment of vitamin D.

Longitudinal follow-up of bone mineral density in children with nephrotic syndrome and the role of calcium and vitamin D supplements

BACKGROUND

We previously have demonstrated that children with idiopathic nephrotic syndrome (INS) are at risk of metabolic bone disease (MBD). In this study, we report the longitudinal follow-up of these children and the role of calcium and vitamin D supplements.

METHODS

We prospectively studied 100 consecutive children with INS. They were treated with prednisone. All were subjected to a baseline clinical, biochemical and radiological evaluation. They were initiated on calcium (500 mg/day) and vitamin D3 (200 IU/day) supplements, followed by a repeat assessment. The primary outcome measure was the Deltaz score (difference between the initial and final z scores) on dual energy X-linked absorptiometry (DEXA). A univariate and multivariate analysis using stepwise linear regression was performed for factors predictive of an improved Deltaz score.

RESULTS

Of the 88 children that completed the study, the majority (n = 54) had improved bone mineral density (BMD) at the spine, and another 25 children had stable BMD on calcium and vitamin D3 supplements. The mean spinal BMD values were significantly better on follow-up (0.607+/-0.013 g/cm2) as compared with baseline values (0.561+/-0.010 g/cm2) (P<0.0001). The interval between initial and follow-up assessment was 1.5+/-0.07 years. Children who were on these supplements (n = 73) had a significantly improved z score as compared with those who did not receive them (n = 15) (P = 0.008). On multivariate analysis, the factors predictive of an improved z score were: younger age (P<0.0001), calcium and vitamin D3 supplement (P<0.0001), greater dietary calcium intake (P = 0.022) and lower interval steroid dose (P = 0.001).

CONCLUSIONS

Children with greater steroid doses were likely to have low BMD on follow-up. Calcium and vitamin D supplements may help in improving BMD in children with INS.

Are children with idiopathic nephrotic syndrome at risk for metabolic bone disease?

BACKGROUND

Children with idiopathic nephrotic syndrome (INS) may be at risk for metabolic bone disease (MBD) because of biochemical derangements caused by the renal disease, as well as steroid therapy. No large study to date has shown conclusively that these children are prone to MBD.

METHODS

We prospectively studied 100 consecutive children with INS for clinical, biochemical, and radiological evidence of MBD. These children were treated with prednisone as follows: initial episode, prednisone, 60 mg/m2/d for 6 weeks, followed by 40 mg/m2 on alternate days for 6 weeks. Relapses were treated with 60 mg/m2/d until remission for 3 days, followed by 40 mg on alternate days for 4 weeks and tapered by 10 mg/m2/wk. Osteoporosis is defined as a bone mineral density (BMD) value evaluated by dual-energy X-linked absorptiometry of the lumbar spine of a z score of 2.5 SDs less than the mean. Univariate and multivariate analyses were performed to analyze for factors predictive of low BMD z score. Children were divided into two groups: those who had received repeated courses of steroid therapy (group II: frequent relapsers (FRs), steroid dependent (SD), or steroid nonresponders (SNRs) versus those who had received infrequent courses (group I: infrequent relapsers).

RESULTS

Twenty-two of 100 children (22%) had osteoporosis. Comparing clinical features, we observed that 6 of 70 children in group II were symptomatic (hypocalcemic signs) compared with none of 30 children in group I (P = 0.10). However, children in group II had significantly lower mean BMD z scores compared with group I (-1.65 +/- 1.35 versus -1.08 +/- 1.0; P = 0.01). Also, 20 of 70 children in group II had osteoporosis compared with 2 of 30 children in group I (P = 0.012). Children in group II had been administered significantly greater doses of steroids compared with group I (P < 0.00001). On multivariate analysis, factors predictive of a low BMD score were older age at onset (P = 0.000), lower total calcium intake (P = 0.000), and greater cumulative steroid dose (P = 0.005).

CONCLUSION

Children with INS are at risk for low bone mass, especially those administered higher doses of steroids (FRs, SD, or SNRs). These children should undergo regular BMD evaluations, and appropriate therapeutic interventions should be planned.