Bone Mineralization In Children Research Articles

Autosomal recessive hypophosphatemic rickets type 2 due to ENPP1 deficiency (ARHR2)

Autosomal recessive hypophosphatemic rickets type 2 (ARHR2; MIM #613312) is a very rare disorder caused by biallelic loss-of-function mutations in the ENPP1 (ectonucleotide pyrophosphatase/phosphodiesterase 1) gene. ENPP1 deficiency encompasses a spectrum of phenotypes that includes, in addition to ARHR2, generalized arterial calcification of infancy (GACI), ossification of the posterior longitudinal ligament (OPLL), and pseudoxanthoma elasticum. ARHR2 can be found in GACI survivors, but it may also be the first manifestation of ENPP1 deficiency. Although the precise mechanisms are not fully elucidated, patients with GACI and ARHR2 have elevated serum FGF23 levels, leading to renal phosphate wasting and hypophosphatemia. As a result, the clinical and radiological phenotype of ARHR2 patients is very similar to that of patients affected with other forms of hypophosphatemic rickets, such as X-linked hypophosphatemia. Patients show signs of rickets (abnormal mineralization of growth plates in children) and osteomalacia (abnormal bone mineralization in children and adults) of varying severity. Clinical manifestations specific to ENPP1 loss-of-function mutations and common to GACI, such as ectopic calcifications (valvular, arterial, or periarticular), deafness, OPLL, and PXE, may also be found. Genetic confirmation of the disease is important so as to ensure that patients receive the appropriate treatment or have the opportunity to participate in clinical trials to evaluate the safety and efficacy of novel and promising recombinant enzyme therapies.

Bone densitometry in children with idiopathic nephrotic syndrome on prolonged steroid therapy: A tertiary multicenter study.

Long-term glucocorticoids administration inhibits bone mineralization and has a negative impact on basic cellular mechanisms that are critical in the development and maintenance of bone strength. Steroids can cause osteoporosis in children and have a negative impact on bone mineral content (BMC) and bone mineral density (BMD).We aim to determine the BMD of children with idiopathic nephrotic syndrome (INS) who are on corticosteroids therapy.This cross-sectional study included 90 patients on corticosteroids therapy and 50 apparently healthy age and sex-matched children served as a control group. Renal functions, bone biochemistry, and parathyroid hormone (PTH) were measured in patients and controls. BMD was measured at the lumbar spinal region (L2–L4) using Dual-energy X-ray absorptiometry (DEXA) scan in both patients and controls groups.Serum PTH, phosphorous, and alkaline phosphatase levels were significantly higher in patients than in controls. There was a statistically significant reduction in blood calcium levels in patients compared to controls. Osteopenia was diagnosed by DEXA scan in 24 patients (26.7%) and osteoporosis in 12 patients (13.3 %). There was a statistically significant decline in BMD-z score, BMD, and BMC in patients compared to the healthy group.Patients with INS on corticosteroids treatment have a lower BMD than their peers. Pediatric INS patients had a high prevalence of osteopenia and osteoporosis as measured by DEXA. Steroid therapy has a deleterious impact on bone mineralization in children with INS.

Influences on Skeletal Health and Bone Mineralization in Children.

Bone is in its most active formation phase of mineralization in the pediatric and adolescent population. Peak bone mass is achieved around the late teens to early 20s. Deficient bone mineralization and decreased peak bone mass acquisition predispose an individual to childhood fractures or lifelong fracture risk. Adolescent fragility or stress fractures should prompt a secondary evaluation for the causes of a low bone mineral content, the root of a fracture. The purpose of this article is to review published literature that discusses the risk factors associated with a decreased bone mineral content in children from birth to the age of peak bone mass. The article also includes a public health planning model for pediatric osteoporosis.

NCPD Tests: Influences on Skeletal Health and Bone Mineralization in Children.

NCPD Tests: Influences on Skeletal Health and Bone Mineralization in Children.

Size-adjustment techniques of lumbar spine dual energy X-ray absorptiometry measurements in assessing bone mineralization in children on maintenance hemodialysis.

Growing skeleton is uniquely vulnerable to impaired mineralization in chronic kidney disease (CKD). Continued debate exists about the optimal method to adjust for body size when interpreting dual energy X-ray absorptiometry (DXA) scans in children with CKD given the burden of poor growth. The study aimed to evaluate the clinical usefulness of size-adjustment techniques of lumber-spine DXA measurements in assessing bone mineralization in children with kidney failure on maintenance hemodialysis (HD). Case-control study included 93 children on maintenance HD (9-18years; 48 males). Participants were subjected to spinal-DXA-scan to obtain areal bone mineral density (aBMD; g/cm2). Volumetric-BMD (vBMD; g/cm3) was mathematically estimated. Z-scores of aBMD for chronological age (aBMDZ-CA), aBMD adjusted for height age (aBMDZ-HA), and vBMDZ-score were calculated using mean and SD values of age subgroups of 442 healthy controls (7-18years). In short-for-age CKD patients, aBMDZ-CA was significantly lower than vBMDZ-score, while aBMDZ-HA was significantly higher than aBMDZ-CA and vBMDZ-score. In normal height-for-age CKD patients, no significant difference between aBMDZ-scores and vBMDZ-score was detected. aBMDZ-CA was significantly lower and aBMDZ-HA was significantly higher in short-for-age compared to normal height-for-age patients without significant differences in vBMDZ-score. We observed age-related decrements in the percentage of HD patients with normal densitometric Z-scores, the effect of age was less pronounced in aBMDZ-HA than vBMDZ-score. vBMDZ-score correlated negatively with age, but not with heightZ-score. Estimated vBMD seems to be a convenient size-adjustment approach of spinal-DXA measurements in assessing BMD especially in older short-for-age children with CKD. aBMDZ-CA underestimates, while aBMDZ-HA overestimates BMD in such patients.

Dietary calcium intake does not meet the nutritional requirements of children with chronic kidney disease and on dialysis

BackgroundAdequate calcium (Ca) intake is required for bone mineralization in children. We assessed Ca intake from diet and medications in children with CKD stages 4–5 and on dialysis (CKD4–5D) and age-matched controls, comparing with the UK Reference Nutrient Intake (RNI) and international recommendations.MethodsThree-day prospective diet diaries were recorded in 23 children with CKD4–5, 23 with CKD5D, and 27 controls. Doses of phosphate (P) binders and Ca supplements were recorded.ResultsMedian dietary Ca intake in CKD4–5D was 480 (interquartile range (IQR) 300–621) vs 724 (IQR 575–852) mg/day in controls (p = 0.00002), providing 81% vs 108% RNI (p = 0.002). Seventy-six percent of patients received < 100% RNI. In CKD4–5D, 40% dietary Ca was provided from dairy foods vs 56% in controls. Eighty percent of CKD4–5D children were prescribed Ca-based P-binders, 15% Ca supplements, and 9% both medications, increasing median daily Ca intake to 1145 (IQR 665–1649) mg/day; 177% RNI. Considering the total daily Ca intake from diet and medications, 15% received < 100% RNI, 44% 100–200% RNI, and 41% > 200% RNI. Three children (6%) exceeded the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (KDOQI) upper limit of 2500 mg/day. None with a total Ca intake < RNI was hypocalcemic, and only one having > 2 × RNI was hypercalcemic.ConclusionsSeventy-six percent of children with CKD4–5D had a dietary Ca intake < 100% RNI. Restriction of dairy foods as part of a P-controlled diet limits Ca intake. Additional Ca from medications is required to meet the KDOQI guideline of 100–200% normal recommended Ca intake.Graphical abstract

Association between maternal smoking and child bone mineral density: a systematic review and meta-analysis.

Maternal smoking during pregnancy has detrimental effects on fetal development. The current review examined the differences in offspring's bone mineral density (BMD) between mothers smoked during pregnancy and those who did not. A systematic review and meta-analysis on the studies investigating the influence of maternal smoking during pregnancy on children or neonates' bone measures published up to October 30, 2018, was performed. BMD results measured at different body sites were pooled and then fixed or random effect models were used based on the presence of heterogeneity. The desired pooled effect size was the offspring's BMD mean difference with 95% confidence interval between smoker and non-smoker mothers. Sensitivity analysis was performed for birth weight and current weight, two important mediator/confounders causing heterogeneity. Overall, eight studies consisting of 17,931 participants aged from infancy to 18years were included. According to the fixed effect model, the mean of BMD in offspring whose mothers smoked during pregnancy was 0.01g/cm2 lower than those with non-smoker mothers (95% CI = - 0.02 to - 0.002). However, subgroup meta-analysis adjusted for birth weight and current weight demonstrated no significant mean difference between BMD of children with smoker and non-smoker mothers (d = 0.06, 95% CI = -0.04 to 0.16, p value = 0.25 and d = - 0.005, 95% CI = - 0.01 to 0.004, p value = 0.28, respectively). According to available studies, it is suggested that maternal smoking during pregnancy does not have direct effect on the offspring's BMD. Instead, this association might be confounded by other factors such as placental weight, birth weight, and current body size of children.

Combined effects of physical activity and calcium on bone health in children and adolescents: a systematic review of randomized controlled trials.

A better understanding of the role of exercise and nutrition in bone health is significant for preventing osteoporosis. The aim of this review was to assess the combined effects of physical activity and calcium intake on improving bone mineral density in children and adolescents. A search of electronic databases (MedLine, ISI Web of Science, Science Direct) and the literature references were performed. Randomized controlled trials published between 1997 and 2017, evaluating the effect of both physical activity and calcium intake intervention on bone mineral density or bone mineral content among children aged 3-18years were selected. The Improved Jadad Rating Scale was used to assess the methodological quality of the included studies. Study characteristics were summarized in accordance with the review's PICO criteria. Changes in bone mineral content were detected at several different bone sites. A total of nine studies involving 908 participants were included in this review. The combined intervention of physical activity and calcium increased bone mineral in children and adolescents, especially when baseline calcium intake level was low and among participants on the stage of early puberty. Regular physical activity combined with high level of calcium intake is beneficial for bone health in young population. Further research is needed to evaluate the dose-response associations and long-term effects of the interaction between physical activity and calcium intake.

The impact of diet, body composition, and physical activity on child bone mineral density at five years of age\u2014findings from the ROLO Kids Study

Bone health is extremely important in early childhood because children with low bone mineral density (BMD) are at a greater risk of bone fractures. While physical activity and intake of both calcium and vitamin D benefit BMD in older children, there is limited research on the determinants of good bone health in early childhood. The aim of this cross-sectional study was to investigate the impact of diet, physical activity, and body composition on BMD at five years of age. Dietary intakes and physical activity levels were measured through questionnaires. Whole body BMD was measured by dual-energy X-ray absorptiometry in 102 children. Child weight, height, circumferences, skinfolds and serum 25-hydroxyvitamin D (25OHD) concentrations were assessed. There was no association between BMD and dietary calcium, dietary vitamin D, 25OHD, physical activity, or sedentary behaviour. Several measures of body composition were significantly positively associated with BMD; however, neither fat mass nor lean body mass was associated with BMD.Conclusion: Although we found no association between self-reported dietary and lifestyle factors and bone health in early years, increased body size was linked with higher BMD. These findings are important as identifying modifiable factors that can improve bone health at a young age is of utmost importance.What is Known:• Bone health is extremely important in early childhood, as children with low bone mineral density (BMD) are at greater risk of bone fractures.• Physical activity has been found to be beneficial for bone health in adolescents, and body composition has also been associated with BMD in teenage years.• Limited research on the determinants of good bone health in early childhood.What is New:• No association between self-reported lifestyle and dietary factors with bone health in early childhood.• Increased body size was associated with higher BMD at five years of age.

Maternal vitamin D in pregnancy and offspring bone measures in childhood: The Vitamin D in Pregnancy study.

Previously we have demonstrated an association between maternal serum 25-hydroxyvitamin D (25(OH)D) during pregnancy and knee-heel length in offspring at birth. However, it is unknown whether maternal serum 25(OH)D is associated with bone measures in childhood. Thus, we aimed to examine associations between 25(OH)D at two stages of pregnancy and offspring bone measures at 11 years. Women were recruited from a single antenatal clinic in Victoria, Australia before 16 weeks gestation and provided two serum samples to determine 25(OH)D status at recruitment and 28-32 weeks gestation. Children and their mothers were followed up at 11 years of age. Children undertook dual energy X-ray absorptiometry scans at the lumbar spine and total body. Maternal 25(OH)D at recruitment (before 16 weeks gestation) was positively associated with the children's bone mineral content and density in boys, but not girls. In boys, a 10 nmol/L (4 ng/mL) increase in maternal 25(OH)D was associated with a median 0.5 g (95% CI 0.1,0.8) and 0.009 g/cm2 (95% CI 0.001,0.017) increase in bone mineral content and density at the spine, respectively, and a median 0.006 g/cm2 (95% CI 0.001,0.011) increase in at the total body. There was no sustained associations with 25(OH)D at the later timepoint (28-32 weeks) with any outcome. At age 11 years, maternal 25(OH)D levels during early pregnancy, but not late were positively associated with bone measures in boys, but not girls.

Variety of activity participation influences leg bone mineral content of pre-pubertal children with developmental coordination disorder

Limited participation in activities in children with developmental coordination disorder (DCD) may have a negative impact on bone mineral accrual. This study aimed to compare bone mineralization and activity participation patterns of pre-pubertal children with DCD and those with typical development, and to determine the relationship between activity participation patterns and bone mineralization in children with DCD. Fifty-two children with DCD (mean age = 7.5 years) and 61 children with typical development (mean age = 7.2 years) participated in the study voluntarily. Appendicular and total body bone mineral content (BMC) and bone mineral density (BMD) were assessed by a whole-body dual-energy X-ray absorptiometry scan. Activity participation patterns were assessed using the Children's assessment of participation and enjoyment (CAPE). Children with DCD had lower appendicular and total body BMCs and BMDs than children with typical development ( P < 0.05). Additionally, they had lower CAPE total activity and physical activity diversity and intensity scores ( P < 0.05). After accounting for the effects of bone age, sex, lean mass and fat mass, the total activity diversity score remained independently associated with leg BMC in children with DCD, explaining 5.5% of the variance ( P < 0.001). However, the physical activity diversity score was no longer associated with leg BMC ( P = 0.084). Diversity (variety) and intensity of activity participation and bone mineralization were lower in pre-pubertal children with DCD. Decreased total activity participation variety was a contributing factor to lower BMC in the legs of children with DCD.

Diversity of activity participation determines bone mineral content in the lower limbs of pre-pubertal children with developmental coordination disorder.

Limited activity participation in children with developmental coordination disorder (DCD) may have a negative impact on bone mineral accrual. The objectives of this study were to compare bone mineralization and activity participation patterns of pre-pubertal children with DCD and those with typical development, and to determine the association between activity participation patterns and bone mineralization in children with DCD. Fifty-two children with DCD (mean age = 7.51years) and 61 children with typical development (mean age = 7.22years) participated in the study. Appendicular and total body (less head) bone mineral content (BMC) and bone mineral density (BMD) were evaluated by a whole-body dual-energy X-ray absorptiometry scan. Activity participation patterns were assessed using the Children's Assessment of Participation and Enjoyment (CAPE) questionnaire. Children with DCD had lower appendicular and total body BMCs and BMDs than children with typical development overall (p < 0.05). They also had lower CAPE total activity and physical activity diversity scores (p < 0.05). After accounting for the effects of age, sex, height, lean mass, and fat mass, the total activity diversity score remained independently associated with leg BMC in children with DCD, explaining 5.1% of the variance (p = 0.030). However, the physical activity diversity score was no longer associated with leg BMC (p = 0.090). Diversity of activity participation and bone mineralization were lower in pre-pubertal children with DCD. Decreased total activity participation diversity was a contributing factor to lower BMC in the legs of children with DCD.

Bone Mineralization and Fracture Risk Assessment in the Pediatric Population

Identifying children most susceptible to clinically significant fragility fractures (low trauma fractures or vertebral compression fractures) or recurrent fractures is an important issue facing general pediatricians and subspecialists alike. Over the last decade, several imaging technologies, including dual-energy X-ray absorptiometry and peripheral quantitative computed tomography, have become useful to identify abnormal bone mineralization in children and in adolescents. This review aimed to summarize the latest literature on the utility of these modalities as they pertain to use in pediatrics. In addition, we review several disease states associated with poor bone health and increased fracture risk in children, and discuss the implications of low bone mineral density in these patients. Finally, we will highlight the gaps in knowledge with regard to pediatric bone health and make recommendations for future areas of research.

Shoulder Function and Bone Mineralization in Children with Obstetric Brachial Plexus Injury After Neuromuscular Electrical Stimulation During Weight-Bearing Exercises.

The purpose of this study was to evaluate the effects of neuromuscular electrical stimulation during weight-bearing exercises on shoulder function and bone mineral density (BMD) in children with obstetric brachial plexus injury (OBPI). This study was a randomized controlled trial. Forty-two children with OBPI were recruited. Their ages ranged from 3 to 5 years. They were randomly assigned either to control group (received a selected program) or study group (received the same program as the control group and neuromuscular electrical stimulation during weight bearing). Mallet grading system and dual-energy x-ray absorptiometry were used to evaluate shoulder function and BMD respectively at entry and after intervention (3 months later). No significant differences of the outcome measures were detected at entry. Significant differences were observed within both groups when the pre and post treatment scores within each group were compared. Finally, significant differences favoring the study group were recorded when their post treatment scores were compared. Neuromuscular electrical stimulation during weight bearing exercises is an effective and simple method to improve shoulder function and BMD in children with OBPI.

Bone mineralization in children with Wilson's disease.

The goal of this study was to determine bone mineralization in children with Wilson's disease (WD). Twenty-seven patients (16 males) and two age- and gender-matched healthy children for each patient were enrolled in the study. Bone mineral content (BMC, grams) and density (BMD, g/cm(2)) at lumbar 1-4 vertebrae were measured by dual-energy X-ray absorptiometry. Urinary calcium excretion was calculated in 19 patients. The effect of cirrhosis and hypercalciuria on BMC and BMD was also evaluated in WD patients. There was no statistically significant difference between patients and healthy controls regarding mean BMC (33.0 ± 13.9 vs. 35.8 ± 13.8 g) (p = 0.940) and mean BMD values (0.66 ± 0.16 vs. 0.71 ± 0.18 g/cm(2)) (p = 0.269), respectively. Nine (47.4 %) patients had hypercalciuria. Hypercalciuric patients had statistically significant lower BMC and BMD values than those without hypercalciuria. A significant difference continued to be present after age, weight, height, and pubertal stage adjustment was done, but disappeared after weight, height, follow up duration, and pubertal stage adjustment was done. The presence of cirrhosis did not affect BMC and BMD significantly in WD patients. BMC and BMD in children with WD were normal. The presence of hypercalciuria but not cirrhosis may affect BMC and BMD negatively in the patients.

3.5. The feasibility of measuring body weight on CT images and the first steps in anatomical mirroring

Objective To estimate body weight using the data of a post mortem total body CT scan and establish its efficacy in a forensic context. Material and method PMCT data were used to compute fat, soft tissue and bone volume using in house developed software based on density and HU. The digitally calculated body weight was then compared with the measured body weight on autopsy. Results Analysis of the obtained results showed a good correlation between the measured body weight and the CT-derived body weight. The highest discrepancies were noticed in children and decomposed bodies presumably due to different bone mineralization in children versus adults and putrefactive gas formation and liquefaction in decomposed bodies. In general, there was no distinct consistent over- or underestimation. In case of partial scans, where a body part was not scanned or was missing, mirroring the unaffected side was seen to give equally good results. Conclusion The weight of a body can be sufficiently estimated using volume measurements of different body tissues obtained from the PMCT data. This technique can be applied when concern is raised about the documented body weight, or if weighing was omitted all together. Furthermore the aforementioned body weight estimates can be useful in case of mass casualties, for victim identification purposes, or in case of traumatic deaths (e.g. dismemberments).

Lead exposure influence on children's bone mineral density

Lead exposure is toxic to children.With the development of industry,lead exposure of children becomes more and more serious.Bone is the major target organ for lead loading.In terms of bone development,childhood is a critical period for the production of peak bone mass,and keeping it normal is important for the measurement of bone health and decreasing the morbidity of osteoporosis.Recent research revealed that children's bone mineral density is affected by elevated level of blood lead and this effect is mainly through the inhibition of the activity of osteoblast cell,the influence on calcium and phosphorus metabolism,and the retardation of children's bone growth.Therefore,the review focuses on the source,toxic effect,and the influence on bone mineral density and its mechanism of children lead exposure. Key words: Children; Lead exposure; Source; Toxic effect; Bone mineral density

Assessment of bone mineral status in children with Marfan syndrome

Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder with skeletal involvement. It is caused by mutations in fibrillin1 (FBN1) gene resulting in activation of TGF-β, which developmentally regulates bone mass and matrix properties. There is no consensus regarding bone mineralization in children with MFS. Using dual-energy X-ray absorptiometry (DXA), we evaluated bone mineralization in 20 children with MFS unselected for bone problems. z-Scores were calculated based on age, gender, height, and ethnicity matched controls. Mean whole body bone mineral content (BMC) z-score was 0.26 ± 1.42 (P = 0.41). Mean bone mineral density (BMD) z-score for whole body was −0.34 ± 1.4 (P = 0.29) and lumbar spine was reduced at −0.55 ± 1.34 (P = 0.017). On further adjusting for stature, which is usually higher in MFS, mean BMC z-score was reduced at −0.677 ± 1.37 (P = 0.04), mean BMD z-score for whole body was −0.82 ± 1.55 (P = 0.002) and for lumbar spine was −0.83 ± 1.32 (P = 0.001). An increased risk of osteoporosis in MFS is controversial. DXA has limitations in large skeletons because it tends to overestimate BMD and BMC. By adjusting results for height, age, gender, and ethnicity, we found that MFS patients have significantly lower BMC and BMD in whole body and lumbar spine. Evaluation of diet, exercise, vitamin D status, and bone turnover markers will help gain insight into pathogenesis of the reduced bone mass. Further, larger longitudinal studies are required to evaluate the natural history, incidence of fractures, and effects of pharmacological therapy. © 2012 Wiley Periodicals, Inc.

Decreased bone mineralization in children with Noonan syndrome: Another consequence of dysregulated RAS MAPKinase pathway?

IntroductionNoonan syndrome (NS) is a disorder of RAS- mitogen activated protein kinase (MAPK) pathway with clinical features of skeletal dysplasia. This pathway is essential for regulation of cell differentiation and growth including bone homeostasis. Currently, limited information exists regarding bone mineralization in NS. Materials and methodsUsing dual-energy X-ray absorptiometry (DXA), bone mineralization was evaluated in 12 subjects (mean age 8.7years) with clinical features of NS. All subjects underwent genetic testing which showed mutations in PTPN11 gene (N=8) and SOS1 gene (N=1). In a subgroup of subjects with low bone mass, indices of calcium-phosphate metabolism and bone turnover were obtained. Results50% of subjects had low bone mass as measured by DXA. Z-scores for bone mineral content (BMC) were calculated based on age, gender, height, and ethnicity. Mean BMC z-score was marginally decreased at −0.89 {95% CI −2.01 to 0.23; p=0.1}. Mean total body bone mineral density (BMD) z-score was significantly reduced at −1.87 {95% CI −2.73 to −1.0; p=0.001}. Mean height percentile was close to - 2 SD for this cohort, thus total body BMD z-scores were recalculated, adjusting for height age. Adjusted mean total body BMD z-score was less reduced but still significant at −0.82 {95% CI −1.39 to −0.25; p=0.009}. Biochemical evaluation for bone turnover was unremarkable except serum IGF-I and IGF-BP3 levels which were low-normal for age. DiscussionChildren with NS have a significantly lower total body BMD compared to age, gender, ethnicity and height matched controls. In addition, total BMC appears to trend lower in children with NS compared to controls. We conclude that the metabolic bone disease present resulted from a subtle variation in the interplay of osteoclast and osteoblast activity, without clear abnormalities being defined in the metabolism of either. Clinical significance of this finding needs to be validated by larger longitudinal studies. Also, histomorphometric analysis of bone tissue from NS patients and mouse model of NS may further elucidate the relationship between the RAS-MAPK pathway and skeletal homeostasis.

Non‐alcoholic fatty liver disease is associated with low bone mineral density in obese children

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in children. Liver disease can be a cause of low bone mineral density. Whether or not NAFLD influences bone health is not known. To evaluate bone mineral density in obese children with and without NAFLD. Thirty-eight children with biopsy-proven NAFLD were matched for age, gender, race, ethnicity, height and weight to children without evidence of liver disease from the National Health and Nutrition Examination Survey. Bone mineral density was measured by dual energy X-ray absorptiometry. Age and gender-specific bone mineral density Z-scores were calculated and compared between children with and without NAFLD. After controlling for age, gender, race, ethnicity and total per cent body fat, the relationship between bone mineral density and the severity of histology was analysed in children with NAFLD. Obese children with NAFLD had significantly (P < 0.0001) lower bone mineral density Z-scores (-1.98) than obese children without NAFLD (0.48). Forty-five per cent of children with NAFLD had low-bone mineral density for age, compared to none of the children without NAFLD (P < 0.0001). Among those children with NAFLD, children with NASH had a significantly (P < 0.05) lower bone mineral density Z-score (-2.37) than children with NAFLD who did not have NASH (-1.58). The NAFLD was associated with poor bone health in obese children. More severe disease was associated with lower bone mineralisation. Further studies are needed to evaluate the underlying mechanisms and consequences of poor bone mineralisation in children with NAFLD.