title: Evaluation of bone mineral density and bone metabolism in children with multiple bone fractures.
abstract: BACKGROUND
  The aim of the study was to carry out a comprehensive analysis of determinants of multiple bone fractures in children with regard to densitometric indices and markers of bone metabolism.
  
  
  METHODS
  The study involved 112 children aged 5-18 years, including 81 patients with a history of at least 3 bone fractures and 31 healthy patients in a control group. Total body and spinal DXA densitometry of the skeleton (DPX-L apparatus, Lunar) was carried out in all children. Laboratory assays comprised the determination of calcium, phosphorus, magnesium (in the serum and 24-hour urine collection), parathormone, liver metabolite of vitamin D, osteocalcin, bone alkaline phosphatase, and N-terminal cross-linked telopeptide of collagen type I (NTx).
  
  
  RESULTS
  Mean values of DXA Z-score, both in total body and in spinal scans, were significantly lower in children with multiple fractures as compared to controls. In children with multiple fractures, there was a higher prevalence of hypercalciuria, hypermagnesuria and hyperphosphaturia. Decreased levels of the liver metabolite of vitamin D were observed in 20/81 (24.7%) patients in this group and in 6/31 controls. Other findings included a higher level of NTx in 38/75 (50.7%) patients with fractures, an increased activity of bone alkaline phosphatase in 29, and of osteocalcin in 12 patients. In this group, there was a significant negative correlation between biochemical bone turnover markers and low bone mass. Also, lower DXA Z-scores were found in children with higher urinary calcium excretion.
  
  
  CONCLUSIONS
  1. Decreased bone mineral density was the most frequent risk factor for bone fractures in children; it was found in about 2/3 of the patients with multiple bone fractures. 2. Accelerated bone turnover, and, particularly, increased bone resorption, indicates a derangement of bone metabolism in children with multiple fractures. 3. Repeated fractures during the body growth period are an indication for a quantitative evaluation of bone mass, calcium-phosphate metabolism and bone turnover markers.
authors.affiliation: Department of Propedeutics of Paediatrics, Medical University of Lodz. propedeutyka@usk4.umed.lodz.pl
authors.forename: Izabela
authors.initials: I
authors.lastname: Michałus
authors.forename: Danuta
authors.initials: D
authors.lastname: Chlebna-Sokół
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Rusińska
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Jakubowska-Pietkiewicz
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kulińska-Szukalska
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000378:metabolism; D015519:Bone Density; D001842:Bone and Bones / Q000378:metabolism*; D002118:Calcium / Q000652:urine; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D005260:Female; D050723:Fractures, Bone / Q000453:epidemiology* / Q000503:physiopathology*; D006801:Humans; D007015:Hypophosphatemia, Familial / Q000453:epidemiology; D008274:Magnesium / Q000652:urine; D008297:Male; D008664:Metal Metabolism, Inborn Errors / Q000453:epidemiology*; D009104:Multiple Trauma / Q000453:epidemiology* / Q000503:physiopathology*; D014807:Vitamin D / Q000378:metabolism
chemical_list: D015415:Biomarkers; D014807:Vitamin D; D008274:Magnesium; D002118:Calcium