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Published on: June 2, 2022
Rapid Hypercalciuria Induction With Bone Formation Marker Reduction During Immobilization in Children
Haruna Otakeyama-Kakimoto1, Yasuko Ogiwara2, Norikazu Ota3
1Division of Endocrinology and Metabolism, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan; Department of Pediatrics, Kagoshima University Medical and Dental Science, Kagoshima, Japan.
Insights
Pediatric immobilization causes increased urine calcium levels and decreased bone formation markers, unlike adults. Bone resorption markers remained unchanged in children during this period.
Area of Science:
- Pediatric Orthopedics
- Pediatric Endocrinology
- Pediatric Nephrology
Background:
- Immobilization in children can lead to significant physiological changes.
- Understanding bone and calcium metabolism during immobilization is crucial for pediatric patient care.
Purpose of the Study:
- To prospectively investigate hypercalciuria and bone metabolite marker alterations in pediatric patients undergoing immobilization.
- To compare pediatric responses to immobilization-induced metabolic changes with those observed in adults.
Main Methods:
- Prospective study of 13 pediatric patients (median age 7 years) with orthopedic diseases requiring immobilization >2 weeks.
- Collected blood and urine samples to measure urine calcium/creatinine (Ca/Cr) ratio and bone metabolite markers.
- Measurements were taken before and at 1-4 week intervals during and after immobilization.
Main Results:
- Urine Ca/Cr ratio significantly increased within a week of immobilization (P < .01), returning to normal ~6 weeks after mobility.
- Serum alkaline phosphatase (ALP) and bone-specific ALP significantly decreased during immobilization (P < .01), returning to baseline in 2-4 weeks post-immobilization.
- Serum N-terminal telopeptides showed no significant change during immobilization.
Conclusions:
- Pediatric immobilization rapidly increases urinary calcium excretion (hypercalciuria).
- Bone formation markers (ALP) decrease in children during immobilization, contrasting with adults where resorption markers may increase.
- This study provides novel insights into pediatric bone metabolism during immobilization.
Objective:
To prospectively examine the occurrence of hypercalciuria and changes in bone metabolite markers in pediatric patients during immobilization.
Methods:
In total, 13 children with an orthopedic disease requiring immobilization longer than 2 weeks were enrolled. Blood samples were collected after breakfast. Urine samples were collected at the second voiding after waking. The urine calcium/creatinine (Ca/Cr) ratio and various bone metabolite parameters were measured before and every 1 to 4 weeks after the start of immobilization.
Results:
The median patient age was 7 years with a range of 2 to 13 years. Orthopedic diseases in the patients were dislocated hip joint (N = 7), slipped capital femoral epiphysis (N = 2), etc. The urine Ca/Cr ratio increased significantly within a week after immobilization (P < .01) and continued to increase for 2 more weeks. Once immobilization ended, the urine Ca/Cr ratio gradually decreased and returned to the normal range approximately 6 weeks after mobility was achieved (P < .01). Serum alkaline phosphatase (ALP) and bone-specific ALP significantly decreased after immobilization began (P < .01). After immobilization ended, the serum ALP returned to preimmobilization levels in 2 to 4 weeks (P < .01). Serum N-terminal telopeptides did not change significantly during immobilization.
Conclusion:
The urine Ca/Cr ratio immediately increased after immobilization. In contrast to adults, bone formation markers in children decreased during immobilization, whereas bone resorption markers did not increase. To our knowledge, this study is the first to examine bone metabolism markers in children during immobilization.
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