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Mineral metabolism in children with dermatomyositis
M D Perez1, S A Abrams, G Koenning
1Section of Pediatric Rheumatology, Baylor College of Medicine, Houston, TX.
Insights
Children with juvenile dermatomyositis (JDM) show impaired calcium absorption and retention, particularly those on steroid therapy. This suggests a risk of bone mineral loss in JDM patients during active disease phases.
Area of Science:
- Pediatric Rheumatology
- Pediatric Endocrinology
- Bone Metabolism
Background:
- Juvenile dermatomyositis (JDM) is an autoimmune disease affecting children.
- Calcium metabolism is crucial for bone health, especially during childhood growth.
- Steroid therapy is common in managing JDM but may impact bone health.
Purpose of the Study:
- To quantify calcium metabolism in children diagnosed with JDM.
- To compare calcium absorption and retention between JDM patients and healthy controls.
- To investigate the influence of steroid treatment on calcium metabolism in JDM.
Main Methods:
- Utilized dual-tracer stable isotope studies for precise calcium metabolism measurement.
- Included 12 children with JDM, categorized into steroid-treated (JDM-ST) and non-steroid-treated (JDM-NS) groups.
- Compared findings with a control group of 43 healthy children (Group HC).
Main Results:
- Children with JDM on steroids (JDM-ST) exhibited significantly lower calcium absorption (19% vs 30% in HC, p < 0.05).
- JDM-ST patients experienced net daily calcium loss (-35 mg/day vs +140 mg/day in HC, p < 0.01).
- Non-steroid-treated JDM patients (JDM-NS) also showed reduced calcium absorption and retention compared to HC (p < 0.01).
- Decreased bone calcium deposition rates were observed in JDM-ST subjects.
Conclusions:
- Children with JDM face a heightened risk of bone mineral loss.
- Impaired calcium absorption is a key factor contributing to bone loss in JDM.
- Steroid therapy in JDM exacerbates calcium malabsorption and bone mineral loss risk, particularly in active disease stages.
Objective:
To measure calcium metabolism in 12 children with juvenile dermatomyositis (JDM).
Methods:
We used dual-tracer stable isotope studies to measure calcium metabolism in 12 children with JDM and a group of 43 healthy children (Group HC) of similar ages. Five of the JDM subjects were receiving steroids (Group JDM-ST) and 7 were not (Group JDM-NS).
Results:
The rate of calcium absorption in Group JDM-ST was lower than that in Group HC (19 +/- 10% vs 30 +/- 11%, p < 0.05). The lower rate of absorption was associated with a net loss of calcium each day (calculated calcium retention, Vbal, of -35 +/- 14 mg/day compared to +140 +/- 97 mg/day in Group HC, p < 0.01). Group JDM-NS showed slightly lower calcium absorption than Group HC and significantly lower Vbal (+33 +/- 70 mg/day, p < 0.01 vs Group HC) than Group HC. Group JDM-ST subjects also had decreased bone calcium deposition rates.
Conclusion:
Patients with JDM may be at risk for significant loss of bone mineral associated with decreased calcium absorption, especially in the acute phase of their disease when they are receiving steroid therapy.