forearm fractures are the most common childhood fracture that presents to the emergency room in the united states . despite improvements in many childhood conditions ,
the incidence of forearm fractures in pediatric patients has increased throughout the last few decades .
more concerning , children with a history of a forearm fracture have a higher risk of entering adulthood with decreased peak bone mass .
although most research efforts have focused on fractures in late adulthood , there is emerging evidence that fractures in childhood may be the initial insult that leads to lifelong bone fragility . in neonates and children ,
vitamin d deficiency has been directly linked to suboptimal bone mineralization and adverse conditions such as rickets and short stature [ 46 ] .
specifically , vitamin d is an important regulator of calcium ( ca ) and phosphorus ( p ) homeostasis , the minerals necessary for bone formation . through its interactions in the kidney and intestine , activation of vitamin d stimulates bone mineralization [ 8 , 9 ] .
furthermore , by the time children enter adolescence 40% of their peak bone mass has been accrued .
dual - energy x - ray absorptiometry ( dxa ) imaging is a widely available clinical tool used in adults to diagnose osteoporosis , predict fracture risk , and monitor response to therapy . with increased concern for future bone health
, investigations using dxa in the pediatric population are becoming an area of high research interest [ 12 , 13 ] . similar to adults , dxa is the preferred imaging modal to measure bone mineral density ( bmd ) and bone mineral content in children due to the precise results , minimally invasive approach , and little exposure to radiation .
multiple studies have demonstrated an association between vitamin d deficiency and fracture risk in children [ 1417 ] .
however , few studies have correlated vitamin d deficiency with bmd , fracture risk , and laboratory markers of bone health . to our knowledge , no study has evaluated vitamin d status , bmd , and serologic markers of bone health in children from a developing country presenting to the emergency room with a forearm fracture .
therefore , the aim of this study is to determine the prevalence of vitamin d deficiency and its effects on bmd in egyptian children presenting with forearm fractures .
we hypothesize that egyptian children with forearm fractures have lower serum 25-hydroxy - vitamin d levels and bmd z - scores compared to children without forearm fractures .
this study was conducted at ain shams university hospital ( asuh ) in cairo , egypt .
the ethical committee of asuh approved the study which was conducted between december 2012 and june 2013 which corresponds to winter and spring in egypt .
children between the ages of 3 and 10 years who presented to the emergency room at asuh and had a confirmed radiologic fracture to the radius , ulna , or both were included in the study as cases .
controls were children who had forearm pain or trauma but did not have radiographic evidence of forearm fracture .
children were excluded from the study if they had a previous history of fractures , prolonged immobilization , or chronic use of antiepileptic drugs or glucocorticoids .
children with chronic illnesses that may interfere with bone health such as kidney disease or intestinal malabsorption were also excluded .
this was a prospective case control study in children with or without forearm fractures to determine their vitamin d status and its impact on bmd .
intake data was categorized into adequate , suboptimal , and low intake using the us department of agriculture nutrient database for standard reference   ( table 1 ) .
extent of sun exposure was also categorized into daily , weekly , or no sun exposure .
all total body bmd measurements were performed using a hologic discovery ci / wi bone densitometer ( hologic , bedford , massachusetts , usa ) by a certified radiology technologist .
measurement results were obtained using hologic 's internal pediatric data software which takes into account patient 's height , weight , and gender .
a z - score of zero was equivalent to the mean , while a z - score between 1 and + 1.5 was equivalent to values of one standard deviation below and 1.5 standard deviations above the mean , respectively . per the international society for clinical densitometry ,
a z - score less than or equal to 2 is defined as  low bone mass or bone mineral density  .
the following laboratory tests were obtained in all subjects : serum ca was measured via colorimetric assay ( o - cresolphthalein complexone method ) using sp120 autochemistry analyzer ( spectrum diagnostics , cairo , egypt ) .
normative values were provided by the manufacturer and were between 9.2 and 11  mg / dl in children of 416 years and 7.2 and 11.2  mg / dl in children of 4 weeks3 years.serum p was measured by one - step colorimetric endpoint method without deproteinization by vitro scient company , cairo , egypt .
expected values were 4.45.5  mg / dl in children of 216 years.serum alkaline phosphatase ( alp ) was measured by one - step colorimetric endpoint ( teco diagnostics , anaheim , ca , usa ) .
normal values stated by the manufacturer include 3292  iu / l.serum vitamin d measurements were analyzed using 25-hydroxy - vitamin d ( i ria kit by diasorin company , still water , mn , usa ) .
serum ca was measured via colorimetric assay ( o - cresolphthalein complexone method ) using sp120 autochemistry analyzer ( spectrum diagnostics , cairo , egypt ) .
normative values were provided by the manufacturer and were between 9.2 and 11  mg / dl in children of 416 years and 7.2 and 11.2  mg / dl in children of 4 weeks3 years .
serum p was measured by one - step colorimetric endpoint method without deproteinization by vitro scient company , cairo , egypt .
serum alkaline phosphatase ( alp ) was measured by one - step colorimetric endpoint ( teco diagnostics , anaheim , ca , usa ) .
serum vitamin d measurements were analyzed using 25-hydroxy - vitamin d ( i ria kit by diasorin company , still water , mn , usa ) .
categorization of 25-oh - vitamin d results followed the recommendations from the american academy of pediatrics : sufficiency > 20100  ng / ml.insufficiency > 1520  ng / ml.deficiency 15  ng
/ ml.severe deficiency 5  ng / ml . sufficiency > 20100  ng / ml . insufficiency > 1520  ng / ml . deficiency 15  ng / ml . severe deficiency 5  ng / ml . continuous data was analyzed using student 's t - test , and categorical data was analyzed using chi - squared analysis , or fisher 's exact test where appropriate .
stata v.13 ( microsoft corporation , college station , texas , usa ) was used to analyze data .
the mean age was 7.2  2.0 years , and 61% of subjects were boys .
overall , half of the participants in the study had suboptimal or low intake of vitamin d and ca . however , 30% of the subjects in the cases group reported low vitamin d and ca intake compared to 4% in the controls group ( p  0.05 ) .
values for all serum ca labs drawn ranged from 5.5 to 11.3  mg / dl with a mean of 8.8  mg / dl .
serum alp levels drawn ranged from 160 to 400  iu / l , with a mean of 245 
children with fractures had statistically significant lower serum ca values ( p  0.05 ) and higher serum alp levels when compared with the controls group ( p  0.05 ) .
vitamin d measurements ranged from 1.3 to 100  ng / ml with a mean of 38  ng / ml . our study had one patient that was vitamin d deficient and eight patients with severe vitamin d deficiency .
the four subjects in the cases group with no reported sun exposure all had severe vitamin d deficiency .
the mean z - score in cases was 0.19  1.99 and 0.3  1.04 in the controls group ( p = 0.3 ) .
the 7 cases with severe vitamin d deficiency had a z - score 2 ( low bone mineral density ) .
the single patient in the controls group that had severe vitamin d deficiency had a z - score of 1.9 .
graphic representation is seen in figure 1 . as shown in figure 2 , serum ca had correlations with serum 25-oh - vitamin d levels ( p  0.01 ) .
there were no significant correlations found between serum 25-oh - vitamin d and phosphorus or alkaline phosphatase .
no association was found between vitamin d and gender , age , or body mass index ( bmi ) .
this study found a high percentage of severe vitamin d deficiency in egyptian children with forearm fractures .
furthermore , this study demonstrates that 25-oh - vitamin d is an important marker of bone mineralization in children with fractures .
[ 17 , 18 ] who found that a significant proportion of children with forearm fractures were vitamin d insufficient [ 21 , 22 ] . in our study , 33% of children had vitamin d insufficiency .
similarly , their studies describe a direct association between 25-oh - vitamin d levels and bmd z - scores .
the patients in our study had overall lower z - scores compared to the subjects in their study ( .06 z - score versus 0.8 z - score ) .
collecting dietary calcium and vitamin d intake and sunlight exposure allows us to infer that the differences in z - scores may be secondary to the suboptimal / low nutritional status ( 50% ) of the egyptian children , as well as the lack of sun exposure [ 24 , 25 ] .
our study included four individuals with no sun exposure who were found to have vitamin d deficiency as well as low bmd measurements .
this was recently emphasized by studies comparing indoor and outdoor training in athletes and found significant lower vitamin d levels in those with indoor training .
our study adds to the growing literature that supports the importance of outdoor sunlight exposure for children .
studies as early as the industrial revolution in europe have demonstrated bone deformities in children living in the inner cities exposed to minimal sun exposure .
this study showed a significant correlation between serum calcium levels and vitamin d. vitamin d plays an important role in calcium homeostasis through its absorption in the intestine and kidney . in cases of poor calcium intake or absorption ,
1,25-hydroxyvitamin d mobilizes ca from bone thereby inhibiting mineral deposition into the osteoid matrix [ 29 , 30 ] . in postmenopausal women , low levels of serum calcium
furthermore , poor calcium intake and distal forearm fractures during childhood are strong predictors of skeletal fragility in adulthood [ 32 , 33 ] . in agreement with our results michaus et al . found lower mean values of bmd z - scores with higher alkaline phosphatase levels in children who had multiple bone fractures . in our study , although serum alp levels were within normal reference values , they were significantly higher in those with fractures .
the importance of serum calcium and alkaline phosphatase as markers for abnormal bone health and osteomalacia has been described in the study by peach et al . .
in their study , they found elevated plasma alkaline phosphatase and hypocalcemia in 48% of patients diagnosed histologically as having osteomalacia . moreover , alkaline phosphatase measurements have recently been recommended as a screening tool for osteomalacia . also , alp has been described as a screening tool for preterm newborns at risk for metabolic bone disease , especially when accompanied with low serum phosphate .
we found that cases have significant higher body mass index ( bmi ) than controls , p = 0.01 .
this supports other studies which found that high adiposity is associated with increased risk of forearm fractures in children .
this study is important because children who develop vitamin d deficiency can potentially have life - long complications .
considering that peak bone mass is reached by the end of the second decade of life , children with early fractures have a high probability of future fracture and more concerning osteoporosis later in life [ 39 , 40 ] . thus improvement in awareness of bone health in the pediatric population can directly impact on quality of life .
although pubertal status is important in evaluating bmd , our subjects were in the age between 3 and 10 years which is less than the optimal age of puberty in egyptian children .
a major limitation of this study is the small number of subjects included in the study .
this study demonstrates that vitamin d insufficiency / deficiency is common among middle eastern children .
 
 objective . to determine the likelihood of vitamin d deficiency and low bone mineral density in egyptian children with forearm fractures 
 . methods . a case control study of 46 children aged 3 to 10 years with or without forearm fractures . 
 validated questionnaires were used to assess calcium and vitamin d intake as well as sun exposure . 
 serum calcium , phosphorus , alkaline phosphatase , and 25-hydroxy - vitamin d were collected . 
 bone mineral density was evaluated using dual - energy x - ray absorptiometry . 
 results . compared to the control group , 
 calcium and vitamin d intake was lower in the cases group ( p = 0.03 ) . 
 cases had higher body mass index than controls , p = 0.01 . 
 children in the cases group had lower mean serum calcium values 8.3  1.4 compared to 9.3  1.1 in controls ( p = 0.01 ) . 
 alkaline phosphatase was higher in cases 265  65.8 than controls 226  54.6 ( p = 0.03 ) . 
 vitamin d and bone mineral density scores were significantly lower in the cases group ( p < 0.05 ) . conclusion . 
 our data shows an increased rate of vitamin d deficiency and decreased bone mineral density in egyptian children with forearm fractures . 