Mild Idiopathic Infantile Hypercalcemia-Part 2: A Longitudinal Observational Study
Nina Lenherr-Taube1, Michelle Furman1, Esther Assor1
1Department of Pediatrics, Division of Endocrinology, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
The Journal of Clinical Endocrinology and Metabolism
|June 17, 2021
Summary
Dietary changes for idiopathic infantile hypercalcemia (IIH) improved calcium levels but not vitamin D. This condition requires treatments targeting vitamin D metabolism to prevent worsening kidney calcification.
Area of Science:
- Pediatric Endocrinology
- Genetics
- Nephrology
Background:
- Idiopathic infantile hypercalcemia (IIH) is a rare disorder with diverse clinical manifestations.
- The long-term effects of dietary modifications and their impact on IIH progression are not well understood.
Purpose of the Study:
- To evaluate the clinical and biochemical outcomes of dietary calcium and vitamin D restriction in children with mild, genetically characterized IIH.
Main Methods:
- A longitudinal observational cohort study involving 20 children diagnosed with mild IIH.
- Prospective monitoring included biochemical markers, dietary intake, and renal ultrasounds every 4-6 months for a median of 21 months.
Main Results:
- Dietary calcium restriction improved serum and urinary calcium levels.
- However, elevated 1,25 dihydroxyvitamin D (1,25(OH)2D) persisted, and renal calcification worsened in 2 subjects.
- No significant differences in response were observed between patients with CYP24A1 or SLC34A1/A3 variants.
Conclusions:
- Dietary interventions for mild IIH offer partial benefits, normalizing calcium but not consistently resolving hypervitaminosis D or preventing renal calcification.
- Future therapies should focus on addressing the underlying vitamin D metabolism defect in IIH.
