Skeletal findings in the first 12 months following initiation of glucocorticoid therapy for pediatric nephrotic syndrome

Incident vertebral fractures and lumbar spine bone mineral density (BMD) were assessed in the 12 months following glucocorticoid initiation in 65 children with nephrotic syndrome. The incidence of vertebral fractures was low at 12 months (6 %) and most patients demonstrated recovery in BMD Z-scores by this time point.

INTRODUCTION

Vertebral fracture (VF) incidence following glucocorticoid (GC) initiation has not been previously reported in pediatric nephrotic syndrome.

METHODS

VF was assessed on radiographs (Genant method); lumbar spine bone mineral density (LS BMD) was evaluated by dual-energy X-ray absorptiometry.

RESULTS

Sixty-five children were followed to 12 months post-GC initiation (median age, 5.4 years; range, 2.3-17.9). Three of 54 children with radiographs (6 %; 95 % confidence interval (CI), 2-15 %) had incident VF at 1 year. The mean LS BMD Z-score was below the healthy average at baseline (mean ± standard deviation (SD), -0.5 ± 1.1; p = 0.001) and at 3 months (-0.6 ± 1.1; p < 0.001), but not at 6 months (-0.3 ± 1.3; p = 0.066) or 12 months (-0.3 ± 1.2; p = 0.066). Mixed effect modeling showed a significant increase in LS BMD Z-scores between 3 and 12 months (0.22 SD; 95 % CI, 0.08 to 0.36; p = 0.003). A subgroup (N = 16; 25 %) had LS BMD Z-scores that were ≤-1.0 at 12 months. In these children, each additional 1,000 mg/m(2) of GC received in the first 3 months was associated with a decrease in LS BMD Z-score by 0.39 at 12 months (95 % CI, -0.71 to -0.07; p = 0.017).

CONCLUSIONS

The incidence of VF at 1 year was low and LS BMD Z-scores improved by 12 months in the majority. Twenty-five percent of children had LS BMD Z-scores ≤-1.0 at 12 months. In these children, LS BMD Z-scores were inversely associated with early GC exposure, despite similar GC exposure compared to the rest of the cohort.

The development of bone mineral lateralization in the arms

Bone mineral content (BMC) is known to be greater in the dominant arm after the age of 8 years. We studied a group of children and found that BMC sidedness gradually increased up to the age of 6 years and then remained stable into late adolescence.

INTRODUCTION

Bone mineral content (BMC) exhibits sidedness in the arms after the age of 8 years, but it is not known whether BMC is greater in the dominant arm from birth or whether lateralization develops in early childhood. To address this, we examined bone mineral status in relation to handedness and age.

METHODS

Subjects (N = 158) were children recently initiating glucocorticoids for underlying disease (leukemia 43 %, rheumatic conditions 39 %, nephrotic syndrome 18 %). Handedness was determined by questionnaire and BMC by dual-energy X-ray absorptiometry.

RESULTS

Median age was 7.2 years (range, 1.5 to 17.0 years), 49 % was male, and the spine BMD Z-score was -0.9 (SD, 1.3). By linear regression, BMC sidedness in the arms was significantly related to age (r = 0.294, p = 0.0005). Breakpoint analysis revealed two lines with a knot at 6.0 years (95 % CI, 4.5-7.5 years). The formula for the first line was: dominant:nondominant arm BMC ratio = 0.029 × age [in years] + 0.850 (r = 0.323, p = 0.017). The slope of the second line was not different from 0 (p = 0.332), while the slopes for the two lines were significantly different (p = 0.027).

CONCLUSIONS

These results show that arm BMC sidedness in this patient group develops up to age 6 years and then remains stable into late adolescence. This temporal profile is consistent with mechanical stimulation of the skeleton in response to asymmetrical muscle use as handedness becomes manifest.

Prevalent vertebral fractures among children initiating glucocorticoid therapy for the treatment of rheumatic disorders

OBJECTIVE

Vertebral fractures are an under-recognized problem in children with inflammatory disorders. We studied spine health among 134 children (87 girls) with rheumatic conditions (median age 10 years) within 30 days of initiating glucocorticoid therapy.

METHODS

Children were categorized as follows: juvenile dermatomyositis (n = 30), juvenile idiopathic arthritis (n = 28), systemic lupus erythematosus and related conditions (n = 26), systemic arthritis (n = 22), systemic vasculitis (n = 16), and other conditions (n = 12). Thoracolumbar spine radiograph and dual x-ray absorptiometry for lumbar spine (L-spine) areal bone mineral density (BMD) were performed within 30 days of glucocorticoid initiation. Genant semiquantitative grading was used for vertebral morphometry. Second metacarpal morphometry was carried out on a hand radiograph. Clinical factors including disease and physical activity, calcium and vitamin D intake, cumulative glucocorticoid dose, underlying diagnosis, L-spine BMD Z score, and back pain were analyzed for association with vertebral fracture.

RESULTS

Thirteen vertebral fractures were noted in 9 children (7%). Of these, 6 patients had a single vertebral fracture and 3 had 2-3 fractures. Fractures were clustered in the mid-thoracic region (69%). Three vertebral fractures (23%) were moderate (grade 2); the others were mild (grade 1). For the entire cohort, mean +/- SD L-spine BMD Z score was significantly different from zero (-0.55 +/- 1.2, P < 0.001) despite a mean height Z score that was similar to the healthy average (0.02 +/- 1.0, P = 0.825). Back pain was highly associated with increased odds for fracture (odds ratio 10.6 [95% confidence interval 2.1-53.8], P = 0.004).

CONCLUSION

In pediatric rheumatic conditions, vertebral fractures can be present prior to prolonged glucocorticoid exposure.

Human endogenous retrovirus with a high genomic sequence homology with IDDMK(1,2)22 is not specific for Type I (insulin-dependent) diabetic patients but ubiquitous

AIMS/HYPOTHESIS

It has been reported recently that a novel human endogenous retroviral gene, insulin-dependent diabetes mellitus (IDDM)K(1,2)22, was expressed in the plasma of Type I diabetic patients but not in that of nondiabetic control subjects. This investigation was initiated to determine the specificity of the selective expression of IDDMK(1,2)22 in diabetic patients.

METHODS

We isolated the total RNA from the plasma and lymphocytes of 13 new onset Type I diabetic patients and 10 normal control subjects and amplified it by reverse transcriptase polymerase chain reaction. We then determined the presence of IDDMK(1,2)22 with a specific primer set, U3/R-poly(A), used in a recent report and the 5 'SAg/3 'SAg primer set recognizing the putative superantigen encoding the region of the IDDMK(1,2)22 envelope (env) gene. In addition, we carried out nested PCR of the U3/R-poly(A) polymerase chain reaction product using U3N/R primers.

RESULTS

We found no difference in the presence of the polymerase chain reaction products between diabetic patients and all nondiabetic subjects tested. Sequencing of the U3/R-poly(A) polymerase chain reaction products showed that the exact sequence of IDDMK(1,2)22 was not present in any of the samples tested, neither in the plasma of diabetic patients nor in that of nondiabetic control subjects. Endogenous retroviral sequences with 90-93% sequence homology to IDDMK(1,2)22 were, however, equally present in both the diabetic and nondiabetic subjects.

CONCLUSION/INTERPRETATION

We conclude that a human endogenous retroviral gene with high sequence homology with IDDMK(1,2)22 is not specific for diabetic patients but, rather, is ubiquitous.

Probable autoimmune thyroid disease and combined immunodeficiency disease

An 8-year-old girl with combined immunodeficiency secondary to adenosine deaminase deficiency developed thyroid failure of probable autoimmune origin manifested by linear growth deceleration, marked bone-age delay, and myxedema. To our knowledge, this association has not been previously reported. Immunologic abnormalities included absolute T-cell lymphopenia and markedly reduced in vitro lymphocyte responses to phytohemagglutinin and to alloantigen in the mixed lymphocyte reaction. The diagnosis of autoimmune thyroid disease was suggested by the presence of antithyroglobulin antibodies in the serum and by decreased, patchy uptake of iodine 123 on a thyroid scan. Autoimmune thyroid disease may have developed because the immunodeficient state, with its greater deficiency of suppressor/cytotoxic T cells, allowed expression of a clone of helper T lymphocytes specific for thyroidal antigens. Thus, autoimmune disease may be more common in immunodeficient states and appropriate surveillance should be instituted.