Osteoporosis as a pediatric problem

Should pediatric idiopathic hypercalciuria be treated with hypocalciuric agents?

BACKGROUND

Hypercalciuria is the most common metabolic risk factor for calcium urolithiasis and is associated with bone loss in adult patients. Reduced bone mineral density (BMD) was already described in idiopathic hypercalciuria (IH) children, but the precise mechanisms of bone loss or inadequate bone mass gain remain unknown. Life-long hypercalciuria might be considered a risk to change bone structure and determine low bone mass throughout life. The peak of bone mass should occur without interferences. A beneficial effect of citrate formulations and thiazides on bone mass in adult and pediatric patients with IH have been shown.

AIM

To evaluate whether pharmacological therapy has a beneficial effect on bone mass in children and adolescents with IH.

METHODS

This retrospective cohort study evaluated 40 hypercalciuric children non-responsive to lifestyle and diet changes. After a 2-mo run-in period of citrate formulation (Kcitrate) usage, the first bone densitometry (DXA) was ordered. In patients with sustained hypercalciuria, a thiazide diuretic was prescribed. The second DXA was performed after 12 mo. Bone densitometry was performed by DXA at lumbar spine (L2-L4). A 24-h urine (calcium, citrate, creatinine) and blood samples (urea, creatinine, uric acid, calcium, phosphorus, magnesium, chloride, hemoglobin) were obtained. Clinical data included age, gender, weight, height and body mass index.

RESULTS

Forty IH children; median age 10.5 year and median time follow-up 6.0 year were evaluated. Nine patients were treated with Kcitrate (G1) and 31 with Kcitrate + thiazide (G2). There were no differences in age, gender, body mass index z-score and biochemical parameters between G1 and G2. There were no increases in total cholesterol, kalemia and magnesemia. Calciuria decreased in both groups after treatment. Lumbar spine BMD z-score increased after thiazide treatment in G2. There was no improvement in G1.

CONCLUSION

Results point to a beneficial effect of thiazide on lumbar spine BMD z-score in children with IH. Further studies are necessary to confirm the results of the present study.

Growth of cortical bone thickness and trabecular bone density in Japanese children

BACKGROUND

The acquisition of a high bone density at a young age is a strategy to prevent fractures/falls later in life. We therefore decided to investigate the increases in cortical thickness (CoTh) and trabecular bone density (TBD) of children.

METHODS

Subjects comprised 1314 students (678 boys and 636 girls) aged between 12 and 18 years. Lifestyle factors were examined with a self-administered questionnaire (sleep times, exercise habits, and calcium intake). Bone growth was assessed based on CoTh and TBD using an ultrasonic bone densitometer. Height, weight, and body fat percentage were also measured.

RESULTS

Increases in CoTh and TBD occurred earlier in girls than in boys. Calcium intake was not sufficient at any of the ages examined, and sleep times were shorter than those recommended by the National Sleep Foundation. Increases in CoTh and TBD occurred subsequent to increases in height. Although increases in CoTh were observed with age in both sexes, TBD increased in boys until the age of 17 years and in girls until the age of 15 years. At 18 years of age, the young adult mean value was greater than 100% for CoTh but lower than 100% for TBD. A multivariate analysis identified age, body mass index (BMI), and exercise as independent positive factors for CoTh, while body fat percentage was an independent negative factor. Age and BMI were independent positive factors for TBD in both sexes, whereas body fat percentage was a positive factor in boys only.

CONCLUSIONS

The study found that CoTH and TBD varied with age and differed in increase in boys and girls; related factors of bone increase could also be found. The results of this study may contribute to the acquisition of high bone density in children and adolescents.

Bone mineral density in adolescent urinary stone formers: is sex important?

Urinary stone disease (USD) is affecting a greater number of children and low bone mineral density (BMD) and increased skeletal fractures have been demonstrated in stone patients; however, the mechanism(s) driving bone disease remain unclear. This pilot study was undertaken to assess an adolescent kidney stone cohort's BMD and evaluate for an inverse correlation between BMD and urine concentration of lithogenic minerals and/or inflammatory levels. Prospective case-control study was carried out at a large pediatric center. 15 participants with USD (12-18 years of age, 8 female) were matched by age, sex, and body mass index to 15 controls. Lumbar and total body BMD z-score did not differ between groups. When stone formers were separated by sex, there was a significant difference between male stone formers vs. controls total body BMD z-score (Fig. 1). BMD z-score did not significantly correlate with urine calcium, oxalate, citrate or magnesium. Higher urine IL-13 did significantly correlate with higher total body BMD z-score (r = 0.677, p = 0.018). Total body BMD z-score did significantly correlate with body mass index (BMI) as expected for the control group (r = 0.6321, p = 0.0133). However, this relationship was not present in the USD group (r = - 0.1629, p = 0.5619). This is a small but hypothesis-generating study which demonstrates novel evidence of male-specific low BMD in adolescent stone formers. Furthermore, we demonstrated a positive association between urine IL-13 and total body BMD z-score USD patients as well as a lack of a positive BMD and BMI correlations in stone formers.

Effects of corn syrup solids containing maltobionic acid (maltobionic acid calcium salt) on bone resorption in healthy Japanese adult women: A randomized double-blind placebo-controlled crossover study

Maltobionic acid is known to have an inhibitory effect on the differentiation of osteoclasts, and it has also been reported in an intervention trial that ingestion of corn syrup solids containing maltobionic acid maintained and increased the bone density of postmenopausal women. However, there is no information on whether maltobionic acid improves bone metabolism in humans. Therefore, we evaluated the influence of corn syrup solids containing maltobionic acid (maltobionic acid calcium salt) on bone resorption markers in healthy Japanese women. Forty-one individuals were selected from 68 participants and assigned to two groups: 21 individuals in the test food antecedent group and 20 individuals in the placebo food antecedent group; individuals in the first group ingested 4 g of corn syrup solids containing maltobionic acid, and subjects in the second group ingested 4 g of placebo (hydrous crystalline maltose and calcium carbonate) for 4 weeks. Bone resorption marker levels (DPD and u-NTx) were evaluated by urinalysis. Forty subjects completed the study, and no adverse events related to the test food were observed. Fourteen subjects were excluded prior to the efficacy analysis because of conflict with the control criteria; the remaining 33 subjects were analyzed. Consumption of corn syrup solids containing maltobionic acid was maintained; DPD and u-NTx values were improved (p < .05). These results indicate that corn syrup solids containing maltobionic acid might contribute to suppress bone resorption and improve bone metabolism in postmenstrual women. (UMIN-CTR ID: UMIN000034257; Foundation: San-ei Sucrochemical Co., Ltd.).

Reference values for digital X-ray radiogrammetry parameters in children and adolescents in comparison to estimates in patients with distal radius fractures

The first objective of this study was to determine normative digital X-ray radiogrammetry (DXR) values, based on original digital images, in a pediatric population (aged 6-18 years). The second aim was to compare these reference data with patients suffering from distal radius fractures, whereas both cohorts originated from the same geographical region and were evaluated using the same technical parameters as well as inclusion and exclusion criteria. DXR-BMD and DXR-MCI of the metacarpal bones II-IV were assessed on standardized digital hand radiographs, without printing or scanning procedures. DXR parameters were estimated separately by gender and among six age groups; values in the fracture group were compared to age- and gender-matched normative data using Student's t tests and Z scores. In the reference cohort (150 boys, 138 girls), gender differences were found in bone mineral density (DXR-BMD), with higher values for girls from 11 to 14 years and for boys from 15 to 18 years (p < 0.05). Girls had higher normative metacarpal index (DXR-MCI) values than boys, with significant differences at 11-14 years (p < 0.05). In the case-control investigation, the fracture group (95 boys, 69 girls) presented lower DXR-BMD at 15-18 years in boys and 13-16 years in girls vs. the reference cohort (p < 0.05); DXR-MCI was lower at 11-18 years in boys and 11-16 years in girls (p < 0.05). Mean Z scores in the fracture group for DXR-BMD were -0.42 (boys) and -0.46 (girls), and for DXR-MCI were -0.51 (boys) and -0.53 (girls). These findings indicate that the fully digital DXR technique can be accurately applied in pediatric populations ≥ 6 years of age. The lower DXR-BMD and DXR-MCI values in the fracture group suggest promising early identification of individuals with increased fracture risk, without the need for additional radiation exposure, enabling the initiation of prevention strategies to possibly reduce the incidence of osteoporosis later in life.

Pelvis width associated with bone mass distribution at the proximal femur in children 10-11 years old

Differences in skeletal geometry may generate different patterns of mechanical loading to bone. Impact and muscle loading during physical activity have been shown to influence skeletal geometry. The purpose of this study was to compare geometric measures of the pelvis and proximal femur (PF) of young children and to analyze the contribution and potential interaction of these geometric measures with physical activity on PF bone mass distribution. Participants were 149 girls and 145 boys, aged 10-11 years. Total body and left hip DXA scans were used to derive pelvic and PF geometric measures and PF bone mineral density (BMD) at the femoral neck (FN), trochanter (TR), and intertrochanter (IT). These subregions were used to represent bone mass distribution via three BMD ratios: FN:PF, TR:PF, and IT:PF. Physical activity was objectively measured using accelerometry, and maturity was estimated as the years of distance from peak height velocity. When compared to boys, girls had a wider pelvic diameter and greater interacetabular distances (p < 0.001), lower BMD at FN, TR, and IT (p < 0.05), and higher TR:PF (p < 0.001). After controlling for maturity, body height, and lean body mass, the interacetabular distance in girls explained 21.1 % (β = 0.713, p < 0.001) in TR:PF and 2.9 % (β = -0.179, p = 0.031) in the IT:PF. Neck-shaft angle explained 5.6 % (β = -0.265, p = 0.001) of the IT:PF and 3.1 % (β = 0.194, p = 0.018) of the FN:PF. In boys, FN axis length explained 2.9 % (β = 0.195, p = 0.040) of TR:PF. There was no main effect of physical activity or interaction effect with pelvic geometry in explaining BMD differences among the subregions of the PF. Even before sexual dimorphism, girls have a wider pelvis than boys, which accounted for proportionally greater BMD of the TR than other subregions of the PF.

Possible mechanisms for the skeletal effects of antipsychotics in children and adolescents

The increasing use of antipsychotics (APs) to treat pediatric psychiatric conditions has led to concerns over the long-term tolerability of these drugs. While the risk of cardiometabolic abnormalities has received most of the attention, preclinical and clinical studies provide preliminary evidence that APs can adversely impact bone metabolism. This would be most concerning in children and adolescents as suboptimal bone accrual during development may lead to increased fracture risk later in life. However, the potential mechanisms of action through which APs may impact bone turnover and, consequently, bone mineral content are not clear. Emerging data suggest that the skeletal effects of APs are complex, with APs directly and indirectly impacting bone cells through modulation of multiple signaling pathways, including those involving dopamine D2, serotonin, adrenergic, and prolactin receptors, as well as by affecting gonadotropins. Determining the action of APs on skeletal development is further complicated by polypharmacy. In children and adolescents, APs are frequently coprescribed with psychostimulants and selective serotonin reuptake inhibitors, which have also been linked to changes in bone metabolism. This review discusses the mechanisms by which APs may influence bone metabolism. Also covered are preclinical and pediatric findings concerning the impact of APs on bone turnover. However, the dearth of clinical information despite the potential public health significance of this issue underscores the need for further studies. The review ends with a call for clinicians to be vigilant about promoting optimal overall health in chronically ill youth with psychopathology, particularly when pharmacotherapy is unavoidable.

Higher Serum Insulin Concentrations Positively Influence the Bone Mineral Density in African American Adolescents

BACKGROUND

Puberty is a developmental stage of increased insulin resistance that also is a critical period for bone mass accrual. Historically, African Americans (AA) have lesser risk for osteoporotic fractures compared to European Americans (EA). AA also have higher incidence of insulin resistance. The possibility that bone health and insulin secretion or concentrations are linked has not been investigated.

AIMS

We aimed to examine the associations of bone mineral density (BMD) and bone mineral apparent density (BMAD) with insulin sensitivity and secretion in healthy adolescent girls and healthy female adults and to evaluate ethnic differences in these associations.

STUDY DESIGN

Observational cohort design.

PLACE AND DURATION OF THE STUDY

University of Alabama at Birmingham, between January 2010 and September 2011.

METHODOLOGY

Healthy, female, non-smoking adolescents and young adults (14-55 years) were enrolled in this observational cohort study.

RESULTS

Adolescents had significantly higher fasting insulin (P=0.0002), insulin area under the curve [AUC] (P= 0.0004) and lower insulin sensitivity (P=0.0005) compared to adults. Among adolescents, AA race was significantly associated with BMD (β=0.086, P=0.01) and BMAD (β=0.0075, P=0.002); however, adjusting for insulin AUC explained this difference. Insulin AUC (β=0.0006, P=0.029) and fasting insulin (β=0.0005, P=0.01) were positively associated with BMAD only in AA adolescents. Insulin AUC and fasting insulin were not significant predictors of BMD for adults.

CONCLUSION

The higher insulin concentration among AA adolescents is associated with increased BMD and higher BMAD.

Higher Serum Insulin Concentrations Positively Influence the Bone Mineral Density in African American Adolescents

Background

Puberty is a developmental stage of increased insulin resistance that also is a critical period for bone mass accrual. Historically, African Americans (AA) have lesser risk for osteoporotic fractures compared to European Americans (EA). AA also have higher incidence of insulin resistance. The possibility that bone health and insulin secretion or concentrations are linked has not been investigated.

Aims

We aimed to examine the associations of bone mineral density (BMD) and bone mineral apparent density (BMAD) with insulin sensitivity and secretion in healthy adolescent girls and healthy female adults and to evaluate ethnic differences in these associations.

Study Design

Observational cohort design.

Place and Duration of the Study

University of Alabama at Birmingham, between January 2010 and September 2011.

Methodology

Healthy, female, non-smoking adolescents and young adults (14–55 years) were enrolled in this observational cohort study.

Results

Adolescents had significantly higher fasting insulin (P=0.0002), insulin area under the curve [AUC] (P= 0.0004) and lower insulin sensitivity (P=0.0005) compared to adults. Among adolescents, AA race was significantly associated with BMD (β=0.086, P=0.01) and BMAD (β=0.0075, P=0.002); however, adjusting for insulin AUC explained this difference. Insulin AUC (β=0.0006, P=0.029) and fasting insulin (β=0.0005, P=0.01) were positively associated with BMAD only in AA adolescents. Insulin AUC and fasting insulin were not significant predictors of BMD for adults.

Conclusion

The higher insulin concentration among AA adolescents is associated with increased BMD and higher BMAD.

Comparison of radiogrammetrical metacarpal indices in children and reference data from the First Zurich Longitudinal Study

BACKGROUND

A number of radiogrammetrical metacarpal indices are in use, some of which have been adapted for children.

OBJECTIVE

The purpose of this study was to compare four known indices-bone mineral density (BMD), relative cortical area, Exton-Smith index, bending breaking resistance index-and the more recently defined pediatric bone index (PBI) according to the two criteria of minimum height dependence and minimum variability in children of equal bone age.

MATERIALS AND METHODS

A total of 3,121 left-hand radiographs from 231 healthy Caucasian children ranging in age from 3 to 19 years old were analysed using BoneXpert®, a programme for automatic analysis of hand radiographs and assessment of bone age.

RESULTS

Dependence on height for chronological age or bone age and the mean relative standard deviation were lowest in the PBI for both genders pooled. The differences in height dependence were statistically significant and are shown to be clinically relevant. Reference data for PBI are presented.

CONCLUSION

PBI may be a better indicator than BMD for bone health in children; however, verification in a clinical group is needed.

Opuntia humifusa supplementation increased bone density by regulating parathyroid hormone and osteocalcin in male growing rats

We investigated the effect of Opuntia humifusa (O. humifusa) supplementation on bone density and related hormone secretion in growing male rats. Sixteen six-week-old male Sprague-Dawley rats were randomly divided into two groups; control diet group (CG, n = 8), and experimental diet group (EG, n = 8). The rats in the CG were given a control diet and those in the EG were given 5% O. humifusa added to the control diet for eight weeks. The serum OC level of the EG was significantly higher than that of the CG, and the serum parathyroid hormone (PTH) level of EG was significantly lower than that of the CG. In addition, the femoral and tibial BMD of the EG were significantly higher values than those of the CG, and the tibial BMC of the EG was significantly higher than that of the CG. These results suggest that O. humifusa supplementation has a positive effect on bone density by suppressing PTH and increasing the OC level in growing male rats.

The IL6 gene polymorphism -634C>G and IL17F gene polymorphism 7488T>C influence bone mineral density in young and elderly Japanese women

Osteoporosis is an important public health problem because of the significant morbidity and mortality associated with its complications, particularly fractures. An important clinical risk factor in the pathogenesis of osteoporosis is the presence of genetic polymorphisms in susceptibility genes. However, few studies have investigated the relevance of these polymorphisms in premenopausal women. Recent studies have demonstrated interactions between bone and immune cells, and that cytokines produced by immune cells regulate bone turnover. In this study, we examined the associations between bone mineral density (BMD) and polymorphisms in genes encoding interleukin (IL)-6 (-634C>G; rs1800796), tumor necrosis factor (TNF)-α (-308G>A; rs1800629), IL-17F (7488T>C; rs763780), transforming growth factor (TGF)-β (869T>C; rs1800470), osteoprotegerin (OPG; 163A>G; rs3102735) and methylenetetrahydrofolate reductase (MTHFR; 677C>T; rs1801133) in young and elderly Japanese women. Whole-body, lumbar spine (L(1) or L(2)-L(4)), and femoral neck BMD were measured in 100 young subjects (18-23 years), and 100 elderly subjects (60-83 years). Whole-body, lumbar spine, and femoral neck BMD were 1.13±0.06, 1.14±0.12, and 1.00±0.11 g/cm(2), respectively, in young subjects, and 0.92±0.09, 0.86±0.15, and 0.63±0.10 g/cm(2), respectively, in elderly subjects. The frequencies of the IL-6 CC, CG, and GG genotypes were 48%, 49%, and 3%, respectively. The frequencies of the IL17F TT, TC, and CC genotypes were 79%, 15%, and 6%, respectively, in young subjects. Polymorphisms of the IL-6 and IL17F genes were significantly associated with BMD. To our knowledge, this is the first report to examine these associations in a cohort of 200 Japanese women.

The relationship between vitamin D receptor gene polymorphisms and bone density, osteocalcin level and growth in adolescents

BACKGROUND/OBJECTIVE

The relationship between vitamin D receptor gene polymorphisms and bone density, osteocalcin and growth was investigated.

SUBJECTS

Eighty eight adolescents aged between 8-15, with no history of illness influencing the level of bone parameters, were examined in our study.

METHODS

Areal BMD for lumbar spine (L1-4) was assessed by dual energy X-ray absorptiometry (DEXA). Height and weight were measured on the day of the DEXA scans. Serum osteocalcin level was determined by using ELISA method. DNA was extracted from white blood cells, amplified by the polymerase chain reaction (PCR) and the polymorphic sites were analyzed by using ApaI, TaqI and FokI restriction enzymes.

RESULTS

The most frequent genotypes were FF (% 54.6), Aa (% 53.4) and Tt (% 48.8). No significant relationship was found between VDR genotypes and areal BMD, osteocalcin level or growth in either sex. But there was a strong tendency for a higher BMD at the lumbar spine of TT and AA genotypes compared to tt and Aa genotypes. The children with TT genotype were taller and heavier than the children with tt genotype

CONCLUSION

Our results suggest that VDR gene TaqI polymorphism may be associated with body weight and bone mass, but more studies with larger groups should be conducted.

The association between dietary protein intake and bone mass accretion in pubertal girls with low calcium intakes

To assess the association between protein intakes and bone mass accrual in girls, data were analysed for 757 pre-pubertal girls (mean age 10.1 years) in urban Beijing, China, who participated in a 5-year study including 2 years of milk supplementation (intervention groups only) and 3 years of follow-up study. At 0, 12, 24, 48 and 60 months from the baseline, bone mass of the proximal or distal forearm (PF or DF) and total body (TB) was measured with dual energy X-ray absorptiometry; dietary intakes were assessed by a 3-d food record (including two weekdays and one weekend day). Linear mixed models were used and continuous variables were logarithm transformed. The mean longitudinal Ca intake (432-675 mg/d on average) positively influenced bone mineral content (BMC) at TB, PF and DF after controlling for baseline bone mass and other possible confounders. However, negative associations were observed between protein intake (55.9-61.0 g/d on average) and BMC accrual at TB, PF or DF (beta = - 1.92, - 10.2 or - 4.82, respectively, P < 0.01) after adjustment. When protein intake was considered according to animal or plant food sources, protein from animal foods, particularly meat, had significant negative effects on BMC accrual at DF or PF after adjustment. It was concluded that higher protein intake, especially from animal foods, appeared to have a negative effect on bone mass accrual in Chinese pubertal girls with low Ca intakes.

The relationships between two different drinking water fluoride levels, dental fluorosis and bone mineral density of children

This field study included the whole population of children aged 10–15 years (77 from a 0.19 mg/L F area; 89 from a 3.00 mg/L F area), with similar nutritional, dietary habits and similar ethnic and socioeconomic status. The fluoride concentration in the drinking water, the bone mineral content, the bone density and the degree of dental fluorosis were determined. The left radius was measured for bone width, bone mineral content, and bone mineral density. The mean fluorosis score was 1.3 in the low fluoride area and 3,6 in the high fluoride area. More than half the children in the low fluoride area had no fluorosis (scores 0 and 1) while only 5% in the high fluoride area had none. Severe fluorosis (30%) was only observed in the high fluoride area. The Wilcoxon Rank Sum Test indicated that fluorosis levels differed significantly (p < 0.05) between the two areas. No relationships were found between dental fluorosis and bone width or between fluorosis and bone mineral density in the two areas (Spearment Rank correlations). A significant increase in bone width was found with age but no differences amongst and boys and girls. A significant positive correlation was found in the high fluoride area between bone mineral density over age. In the 12-13 and 13-14 year age groups in the high fluoride area, girls had higher bone mineral densities. However, a significant negative correlation (p<0.02) was found for the low fluoride area (0.19 mg/L F) over age.

Age-related distribution of bone and skeletal parameters in 1,322 Japanese young women

We explored factors that could serve as indices for therapeutic intervention aimed at prevention of osteoporosis. In this cross-sectional study, we investigated the timing of peak bone mass (PBM) in 1,322 Japanese women aged 12-30 years old. We measured height, body weight, bone mineral density (BMD), bone mineral content (BMC), and bone area at the lumbar spine and total hip, as well as the blood markers calcium, phosphorus, and the bone metabolic markers bone alkaline phosphatase (BAP) and type I collagen cross-linked N-telopeptide (NTX). All measurements were standardized with the mean at age 18 defined as 100% to identify age-related differences. In the total hip, BMD peaked at age 18, while, in the lumbar spine, BMD peaked at age 29, of which 99.8% was attained at age 18, suggesting that peak BMD was attained at age 18 at both the total hip and lumbar spine. No age difference was observed in serum calcium, while there was a 15.1% decrease between ages 12 and 18 in serum phosphorus. There were 273.8% and 208.5% decreases in serum BAP and NTX, respectively, between ages 12 and 18, while these levels remained constant thereafter, suggesting that bone and calcium metabolism are constant between ages 19 and 30. Factors that had stronger correlations with BMD, BMC, and bone area from 12 years to 18 years were height and body weight. PBM was reached at age 18. Control of body weight by using total hip BMD as an index for intervention should be reasonable.

Evaluation of bone mass in children with long bone fracture compared with controls

Childhood is a critical period for achieving skeletal mass. In adults, low bone density is associated with an increased fracture risk and it has been postulated that the same is true for children. If this were the case, we would expect that children with fractures might have a lower bone mass than those without. A case-control study of 30 cases and 30 age and sex-matched controls was carried out. Each child underwent height and weight measurements, a simple interview and phalangeal ultrasound to measure speed of sound. The difference in mean speed of sound was -51.81 m/s (95% confidence interval -83.0 to -20.6; P=0.002) in children with simple long bone fractures versus controls. In children, there appears to be a significant difference in bone mass between those with a simple long bone fracture and those who have never sustained a fracture. To be certain that this is owing to cause rather than effect, and also as this is an important public health issue, further studies are warranted.

Physical activity and bone development during childhood: insights from animal models

Animal studies illustrate greater structural and material adaptations of growing bone to exercise than in adult bones but do not define effective training regimes to optimize bone strength in children. Controlled loading studies in turkey, rat, or mouse bones have revealed mechanisms of mechanotransduction and loading characteristics that optimize the modeling response to applied strains. Insights from these models reveal that static loads do not play a role in mechanotransduction and that bone formation is threshold driven and dependent on strain rate, amplitude, and partitioning of the load. That is, only a few cycles of loading are required at any time to elicit an adaptive response, and distributed bouts of loading, incorporating rest periods, are more osteogenic than single sessions of long duration. These parameters of loading have been translated into feasible public health interventions that exploit the insights gained from animal experiments to achieve adaptive responses in children and adolescents. Studies manipulating estrogen receptors (ER) in mice also demonstrate that skeletal sensitivity to loading during the peripubertal period is due to a direct regulation of mechanotransduction pathways by ER, and not just a simple enhancement of cell activity already marshaled by the hypothalamic-pituitary axis. Unfortunately, because the rate and timing of growth in small animals are completely different from those in humans, these models can be poor tools to elucidate periods during growth in youths, during which the skeleton is more sensitive to loading. However, there are insights from studies of human growth that can improve the interpretation of data from such studies of growth and development in animals.

Circulating leptin levels and bone mineral density in children with biliary atresia

AIM

To investigate circulating leptin levels in biliary atresia (BA) patients and the association of leptin with bone mineral density (BMD) and the severity of BA.

METHODS

We have examined 50 patients with BA and 15 matched healthy controls. Serum leptin, osteocalcin and C-terminal telopeptide of type I collagen (CTX) levels were measured by sandwich enzyme-linked immunosorbent assay (ELISA). BMD of the lumbar spine was measured by dual energy X-ray absorptiometry.

RESULTS

Serum leptin levels of BA patients were lower than those of healthy controls (2.7 +/- 0.3 vs. 7.1 +/- 1.7 ng/mL, p = 0.0001). Among the BA patients, serum leptin levels were significantly lower in patients with jaundice than patients without jaundice (1.7 +/- 0.2 vs. 3.4 +/- 0.4 ng/mL, p = 0.001). BMD of BA patients was correlated (p < 0.001) with leptin levels, age and BMI (r = 0.55, r = 0.75 and r = 0.58, respectively). The serum CTX levels were significantly higher in jaundice patients compared with jaundice-free patients and the healthy controls (0.6 +/- 0.2 vs. 0.2 +/- 0.1 ng/mL, p = 0.01), whereas the serum osteocalcin levels in BA patients were not different from those in the controls.

CONCLUSION

Circulating leptin levels are correlated with BMD and the presence of jaundice in BA, suggesting that the leptin may play a physiological role in maintaining bone mass of BA patients with jaundice.

Sex difference in the effect of puberty on the relationship between fat mass and bone mass in 926 healthy subjects, 6 to 18 years old

OBJECTIVE

Understanding factors influencing bone mineral accrual is critical to optimize peak bone mass during childhood. The epidemic of pediatric obesity and reported higher incident of fracture risk in obese children led us to study the influence of fat mass on bone mineral content (BMC) in children.

RESEARCH METHODS AND PROCEDURES

Height; weight; pubertal stage; and BMC, non-bone fat-free mass (nbFFM), and fat mass (FM) by DXA were obtained in a multiethnic group of healthy children (444 girls/482 boys; 6 to 18 years old) recruited in the New York metropolitan area. Regression techniques were used to explore the relationship between BMC and FM, with age, height, nbFFM, pubertal stage, sex, and ethnicity as covariates.

RESULTS

Because there were significant sex interactions, separate regression analyses were performed for girls and boys. Although ln(nbFFM) was the greatest predictor of ln(BMC), ln(FM) was also a significant predictor in prepubertal boys and all girls but not in pubertal boys. This effect was independent of ethnicity.

DISCUSSION

FM was a determinant of BMC in all girls but in only prepubertal boys. Our study confirms nbFFM as the greatest predictor of BMC but is the first to find a sex difference in the effect of puberty on the relationship of FM to BMC. Our results suggest that, in two individuals of the same sex and weight, the one with greater fat mass will have lower BMC, especially pubertal boys. The implications of these findings for achievement of optimal peak bone mass in a pediatric population with an unprecedented incidence of overweight and "overfat" status remain to be seen.

Direct X-ray radiogrammetry versus dual-energy X-ray absorptiometry: assessment of bone density in children treated for acute lymphoblastic leukaemia and growth hormone deficiency

BACKGROUND

In recent years interest in bone densitometry in children has increased.

OBJECTIVE

To evaluate the clinical application of digital X-ray radiogrammetry (DXR) and compare the results with those of dual-energy X-ray absorptiometry (DXA).

MATERIALS AND METHODS

A total of 41 children with acute lymphoblastic leukaemia (ALL) and 26 children with growth hormone deficiency (GHD) were included in this longitudinal study. Radiographs of the left hand were obtained and used for DXR. DXA of the total body and of the lumbar spine was performed.

RESULTS

In both study populations significant correlations between DXR and DXA were found, and, with the exception of the correlation between DXR bone mineral density (DXR-BMD) and bone mineral apparent density in the GHD population, all correlations had a P-value of <0.001. During treatment a change in DXR-BMD was found in children with GHD.

CONCLUSIONS

Our study showed that DXR in a paediatric population shows a strong correlation with DXA of the lumbar spine and total body and that it is able to detect a change in BMD during treatment.

Effect of micronutrient supplement on health and nutritional status of schoolchildren: bone health and body composition

OBJECTIVE

We investigated the effect of a micronutrient-enriched beverage on body composition, bone mineral content (BMC), bone area, and bone mineral density (BMD) at various sites in schoolchildren.

METHODS

A double-blind, placebo-controlled, matched-pair, cluster, randomization study was carried out in residential schoolchildren 6 to 16 y of age who lived near Hyderabad, India. Children (n = 268) were selected randomly from two classes of each grade (1 to 9) and were provided a micronutrient-enriched beverage (n = 146) or a placebo drink (n = 122). Bone parameters such as BMC, BMD, and bone area at various sites and the entire body were measured with dual-energy X-ray absorptiometry at the beginning and end of the study. Increments of outcome variables were subjected to paired t test with appropriate corrections to assess the effect of the supplement on bone health.

RESULTS

After 14 mo, increments for height, weight, fat-free mass, percentage of fat, whole-body BMC, whole-body bone area, and BMD at the neck of the femur were significantly greater (P < 0.05) in the supplemented group than in the placebo group.

CONCLUSIONS

The micronutrient-rich supplement increased tissue growth and skeletal shell in apparently normal children in the 14-mo period. It did not increase whole-body or site-specific BMD except at the neck of the femur. Amounts of calcium and other nutrients contained in the supplement were inadequate for tissue growth with density increases. This study raises important questions about the nutrient requirements of Indian children who consume a diet of cereals and pulses.

Controlled longitudinal study of bone mass accrual in children and adolescents with cystic fibrosis

BACKGROUND

A study was undertaken to observe the gains in bone mass in children and adolescents with cystic fibrosis (CF) over 24 months and to examine the relationship between areal bone mineral density (aBMD) and associated clinical parameters including physical activity, nutrition, and 25-hydroxyvitamin D (25OHD).

METHODS

Areal BMD of the total body (TB), lumbar spine (LS), and total femoral neck (FNt) were repeatedly measured in 85 subjects aged 5-18 years with CF and 100 age and sex matched controls over 2 years. At each visit anthropometric variables, nutritional parameters, pubertal status, disease severity, physical activity, dietary calcium, caloric intake, and serum 25OHD were assessed and related to aBMD.

RESULTS

After adjusting for age, sex, and height Z-score, gains in LS aBMD in children (5-10 years) and TB and FNt aBMD in adolescents (11-18 years) with CF were significantly less than in controls. Lean tissue mass was significantly associated with TB and LS aBMD gains in children and adolescents and explained a significant proportion of the aBMD deficit observed. Lung function parameters were significantly associated with aBMD gains in adolescents with CF.

CONCLUSIONS

Inadequate bone mass accrual during childhood and adolescence contributes to the low bone mass observed in adults with CF. Accounting for the height discrepancy which is frequently observed in those with CF, in addition to age and sex, is important when assessing low bone mass in children and adolescents with CF. To optimise an individual's potential to acquire maximal bone mass, it is necessary to maximise nutritional status and limit the progression of chronic suppurative lung disease.

Bone mineral metabolism and its relationship to leptin levels in survivors of childhood leukemia and lymphoma

Leptin has important effects on bone metabolism. Possible relationships between leptin and bone mineral density were evaluated in the survivors of the childhood leukemia and lymphoma. Twenty patients were included the study. Anthropometric parameters, growth hormone response to provocative test, serum calcium, phosphorus, alkaline phosphates, osteocalcin, leptin levels, urinary calcium and deoxyypyridinoline levels, and bone mineral density were obtained. Anthropometric parameters of patients were not significantly different from those of a control group. Growth hormone provocative test was abnormal in 3 patients who received cranial radiotherapy. The osteocalcin levels and bone mineral density of patients were significantly lower than in the control group (p=.001, p=.02). Nine patients were in the osteopenic and 7 were in the osteoporotic range. The leptin levels of patients were significantly lower (p=.01) than in the control group. Bone mineral density (BMD) was significantly correlated with leptin level, age, body mass index, and Tanner stage in simple correlation analysis. However, in multivariate analysis only age was significant (p<.000, r: .752). Markers of bone metabolism, BMD, and leptin levels were not related with the growth hormone status of patients and did not present a correlation with the cumulative doses of drugs. There are a few studies evaluating the relationship between BMD and leptin levels in childhood cancer. Although this study did not find any correlation between the leptin level and BMD, detailed studies of larger numbers of patients are necessary to evaluate causes of decreased leptin level and the possible role of leptin on osteopenia observed in survivors of childhood cancer.

Bone mineral density and urinary N-acetyl-beta-D-glucosaminidase activity in paediatric patients with idiopathic hypercalciuria

BACKGROUND

Idiopathic hypercalciuria (IH) is defined as hypercalciuria that persists after correction of dietary inbalances and has no detectable causes. Patients with IH have a higher prevalence of osteoporosis. Defective reabsorption of calcium by the renal tubule is considered a likely mechanism of IH. N-acetyl-beta-D-glucosaminidase (NAG) is a lysosomal enzyme that is a very sensitive marker of renal tubular impairment.

METHODS

Fifteen patients (nine boys and six girls, mean age 12.4 +/- 4.0 years) with IH (urinary calcium excretion >0.1 mmol/kg per 24 h) had their bodyweight, height, body mass index (BMI), urinary NAG/creatinine ratio (U-NAG/Cr) and 24-h urinary calcium excretion (U-Ca/24 h) assessed. L1-L4 bone mineral density (BMD) was measured by dual energy X-ray absorptiometry and volumetric BMD (BMDvol) was calculated. The obtained results were expressed as Z-scores.

RESULTS

The values of basic anthropometric parameters did not differ significantly from the values of the reference population and there was a tendency to short stature, which did not reach statistical significance (P = 0.08). The values of calciuria and U-NAG/Cr were significantly higher while BMD was significantly lower when compared to the reference values (P < 0.0006, P < 0.006 and P < 0.001, respectively). Inverse and significant correlations were found between U-Ca/24 h and BMD, U-Ca/24 h and body height, and U-Ca/24 h and BMDvol (r = -0.64 and -0.70, respectively, P < 0.01; r = -0.55, P < 0.05), while there was no correlation between U-NAG/Cr and U-Ca/24 h, nor between BMD and weight or BMD and BMI.

CONCLUSION

Tubular impairment is highly probable in children with IH, but there is a poor relationship with the degree of calcium leakage. Idiopathic hypercalciuria should be considered as a risk factor for stunted growth and low bone mass.

Oral bisphosphonates to treat disuse osteopenia in children with disabilities: a case series

Children with congenital conditions who are nonambulatory have been observed to have pathologic fractures due to disuse osteopenia. Data support the use of intravenous bisphosphonates to treat this in children with disabilities, but there are no data to guide the use of oral bisphosphonate medication. Ten nonambulatory children with disuse osteopenia secondary to either static brain injury or spina bifida were started on alendronate. Investigators completed a chart review of each subject. There were 17 fractures before starting alendronate and 1 fracture in the follow-up period. All children with nociceptive behavior or pain complaints (5/10) had their symptoms resolve after treatment. Despite the presence of gastrointestinal comorbidities (7/10 with a history of gastroesophageal reflux disease, 5/10 taking reflux medication, and 4/10 with PEG tubes), only 1 of the 10 children discontinued the medication secondary to gastrointestinal complaints. This case series offers evidence that disabled nonambulatory children tolerate alendronate, and it may decrease fractures in those at risk from severe disuse osteopenia.

Increasing weight-bearing physical activity and calcium-rich foods to promote bone mass gains among 9-11 year old girls: outcomes of the Cal-Girls study

Background

A two-year, community-based, group-randomized trial to promote bone mass gains among 9–11 year-old girls through increased intake of calcium-rich foods and weight-bearing physical activity was evaluated.

Methods

Following baseline data collection, 30 5th-grade Girl Scout troops were randomized to a two-year behavioral intervention program or to a no-treatment control group. Evaluations were conducted at baseline, one year, and two years. Measures included bone mineral content, density, and area (measured by DXA), dietary calcium intake (24-hour recall), and weight-bearing physical activity (physical activity checklist interview). Mixed-model regression was used to evaluate treatment-related changes in bone mineral content (g) for the total body, lumbar spine (L1-L4), proximal femur, one-third distal radius, and femoral neck. Changes in eating and physical activity behavioral outcomes were examined.

Results

Although the intervention was implemented with high fidelity, no significant intervention effects were observed for total bone mineral content or any specific bone sites. Significant intervention effects were observed for increases in dietary calcium. No significant intervention effects were observed for increases in weight-bearing physical activity.

Conclusion

Future research needs to identify the optimal dosage of weight-bearing physical activity and calcium-rich dietary behavior change required to maximize bone mass gains in pre-adolescent and adolescent girls.

Pubertal development and its influences on bone mineral density in Australian children and adolescents with cystic fibrosis

BACKGROUND

Pubertal delay is thought to contribute to suboptimal peak bone mass acquisition in young people with cystic fibrosis (CF), leading to an increased fracture incidence. This study aims to compare pubertal development in young people with CF with that of a local healthy population and assess the influence it has on areal bone mineral density (aBMD).

METHODS

Tanner stage, age of menarche, bone age (BA), sex hormone levels and aBMD were examined in 85 individuals with CF (aged 5.3-18.1 years, 39 females) and 100 local controls (5.6-17.9 years, 54 females).

RESULTS

Tanner stage and age of menarche were not significantly different between controls and CF. Tanner stage-adjusted mean values for follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone (T) were lower in males with CF (FSH: P = 0.004, LH: P = 0.01 and T: P = 0.002). Bone age was delayed in adolescents with CF compared to controls (chronological age-BA: controls = 0.13 years (SE = 0.16), CF = 0.95 years (SE = 0.22), P = 0.003). Areal bone mineral density (adjusted for age, sex, height and lean tissue mass) was not significantly different between CF and controls. Moderate negative correlations were found between delayed BA and weight (r = -0.41, P < 0.001) and height (r = -0.41, P < 0.001).

CONCLUSIONS

There was no evidence of clinical pubertal delay or low aBMD (adjusted for short stature and lean tissue mass) in young people with CF when compared with a local population, despite lower nutritional markers, height and weight and delayed skeletal maturation.

The relationship of dietary and lifestyle factors to bone mineral indexes in children

OBJECTIVE

To identify factors related to children's bone mineral indexes at age 8 years, and to assess bone mineral indexes in the same children at ages 6 and 8 years.

DESIGN

Bone mineral content (BMC [g]) and bone mineral density (BMD; calculated as g/cm 2 ) were measured by dual-energy x-ray absorptiometry (DEXA) in children and their mothers when the children were 8 years of age. A subset of children had an earlier DEXA assessment at age 6 years. Children's dietary intake, height, weight, and level of sedentary activity were assessed as part of a longitudinal study from ages 2 months to 8 years.

SUBJECTS/SETTING

Fifty-two healthy white children (25 male, 27 female) and their mothers. Main outcome measures Children's total BMC and BMD at age 8 years.

STATISTICAL ANALYSES PERFORMED

Correlations and stepwise multiple regression analyses.

RESULTS

Factors positively related to children's BMC at age 8 years included longitudinal intakes (ages 2 to 8 years) of protein, phosphorus, vitamin K, magnesium, zinc, energy, and iron; height; weight; and age ( P < or = .05). Factors positively related to children's BMD at age 8 years included longitudinal intakes of protein and magnesium ( P < or = .05). Female sex was negatively associated with BMC and BMD at age 8 years ( P < or = .05). Children's bone mineral indexes at ages 6 and 8 years were strongly correlated ( r =0.86, P < .0001 for BMC; r =0.92, P <.0001 for BMD).

CONCLUSIONS

Because many nutrients are related to bone health, children should consume a varied and nutrient-dense diet.

Reproducibility of pediatric whole body bone and body composition measures by dual-energy X-ray absorptiometry using the GE Lunar Prodigy

The use of dual-energy X-ray absorptiometry (DXA) in pediatrics is increasing. It is safe, readily available, and easily performed, but there is little information on reproducibility. The aim of this study is to evaluate the reproducibility of whole body DXA scans in children. Total and regional bone mineral density, bone mineral content, nonbone, lean fat mass, and percent fat were measured twice by whole body DXA (GE Lunar Prodigy) in 49 subjects (5 to 17 yr). Within each subject, between subjects, and reading standard deviations for each body component were evaluated as well as intraclass correlations (IC) and coefficients of variation (CV). Total body measurements had better IC and CV than regional results from the whole body scan, with legs and arms better than trunk and spine. IC values were >or=0.989 for total body, >or=0.976 for legs and arms, and >or=0.875 for trunk and spine. CV values ranged 0.18 to 1.97% for total body, and 0.96 to 6.91% for regional measures. These values confirm that body composition and bone mass by DXA are highly reproducible among pediatric subjects. The results of this study can be used by clinicians and researchers for interpretation of longitudinal observations and for power calculations.

Longitudinal Changes in Intake and Food Sources of Calcium from Childhood to Young Adulthood: The Bogalusa Heart Study

OBJECTIVE

To examine changes in calcium intake and food sources of calcium from childhood to young adulthood in a longitudinal sample.

METHODS

Information on food and nutrient intake was derived from a single 24-hour dietary recall collected on children who participated in a cross-sectional survey at age 10 and again in young adulthood. A cohort of 237 young adults who participated in the 1989-1991 young adult survey (ages 19 to 28 years) also participated in one of three cross-sectional surveys from 1973 to 1978 at 10 years of age. Repeated measures analysis of variance was applied to examine the longitudinal changes in intake of calcium and food sources from childhood to young adulthood.

RESULTS

Total calcium intake at age 10 was not significantly different than total calcium intake of those same individuals when they were young adults. Gender and ethnic differences were observed within the two age groups. In both childhood (age 10 years) and young adulthood, African-American females had significantly lower total calcium intake than Euro-American males. However, this ethnic difference in total calcium intake did not exist after adjusting for energy intake. Calcium intake per 1000 kcal was significantly lower in females than males at age 10, but not in young adulthood. A large percentage of 10-year-olds did not meet the RDA or AI for calcium intake (54% and 88%, respectively), and this was also shown when they were young adults (77% and 75%, respectively).

CONCLUSIONS

More effective nutrition educational efforts are needed to emphasize the importance of adequate calcium intake and the major food sources of calcium, beginning early in childhood and continuing into young adulthood.

Calcium intake trends and health consequences from childhood through adulthood

Issues involving low calcium intake and dairy product consumption are currently the focus of much debate and discussion at both the scientific and lay community levels. In this review, we examine the following major areas of interest: (1). the role of calcium intake and dairy product consumption in chronic diseases, (2). nutritional qualities of milk and other dairy products, (3). trends in calcium intake and dairy product consumption, (4). current status of calcium intakes and dairy product consumption in children, (5). tracking of calcium intake and diary product consumption, (6). the impact of school meal participation on calcium intake and dairy product consumption, (7). concerns related to calcium-fortified foods and beverages and (8). factors influencing children's milk consumption. To date, the findings indicate that calcium intake and dairy product consumption have beneficial roles in a variety of chronic diseases; dairy products provide an abundant source of vitamins and minerals; calcium intakes of children have increased over time, yet intakes are not meeting the current adequate intake (AI) calcium recommendations; dairy consumption has decreased, and soft drink consumption and, possibly, consumption of calcium-fortified products have increased; consumption of dairy products have a positive nutritional impact on diets of children, particularly from school meals, and there are many factors which influence children's milk consumption, all of which need to be considered in our efforts to promote adequate calcium intakes by children. Based on this review, areas that need immediate attention and future research imperatives are summarized in an effort to further our understanding on what we already know and what we need to know to promote healthier eating habits early in life.

Bone mineral density in Australian children, adolescents and adults with cystic fibrosis: a controlled cross sectional study

BACKGROUND

Low bone mineral density (BMD) is recognised in individuals with cystic fibrosis (CF) although the pathogenesis remains unclear. The aims of this study were to compare BMD over a broad continuum of Australian individuals with CF with healthy controls and to examine the relationship between BMD and clinical parameters including physical activity, nutrition, and vitamin D levels.

METHODS

BMD of the lumbar spine (LS), total body (TB), femoral neck (FN), cortical wrist (R33%), and distal wrist (RUD) was examined in 153 individuals with CF aged 5.3-55.8 years (84 males) and in 149 local controls aged 5.6-48.3 years (66 males) using dual energy x ray absorptiometry. Anthropometric variables, body cell mass, markers of disease severity, corticosteroid usage, measures of physical activity, dietary calcium and caloric intake and serum vitamin D were assessed and related to BMD.

RESULTS

Compared with controls, mean BMD was not significantly different in children aged 5-10 years with CF. Adolescents (females 11-18 years, males 11-20 years) had reduced TB and R33% BMD when adjusted for age, sex, and height (difference in BMD (g/cm2) adjusted means between control and CF: TB=0.04 (95% CI 0.01 to 0.07); R33%=0.03 (95% CI 0.01 to 0.06)). BMD was reduced at all sites except R33% in adults (difference in BMD (g/cm2) adjusted means between control and CF: TB=0.05 (95% CI 0.02 to 0.09); LS=0.08 (95% CI 0.03 to 0.14); FN=0.09 (95% CI 0.03 to 0.15); RUD=0.03 (95% CI 0.01 to 0.05)). In children/adolescents BMD was weakly associated with nutritional status and disease severity.

CONCLUSIONS

BMD was normal in a well nourished group of prepubertal children with CF. A BMD deficit appears to evolve during adolescence and becomes more marked in adults. Individuals with CF should optimise nutrition, partake in physical activity, and maximise lung health in order to optimise BMD. Further longitudinal studies are required to understand the evolution of reduced BMD in young people and adults with CF.

Hyperprolactinemia and bone mineral density: the potential impact of antipsychotic agents

The prevalence of schizophrenia is about 1% worldwide. Individuals with schizophrenia are at increased risk for osteoporosis and fractures for several reasons, including poor diet, lack of exercise, cigarette smoking, and polydipsia. Some antipsychotic medications may further increase the risk of fractures by causing dizziness, orthostatic hypotension, and falls. Studies in women with hyperprolactinemia resulting from pituitary tumors have demonstrated high rates of osteoporosis believed to result from hypoestrogenism. Similarly, hyperprolactinemia in men results in hypogonadism and bone loss. Preliminary surveys have indicated that schizophrenia patients also may have elevated rates of osteoporosis and pathological fractures, possibly resulting in part from the long-term administration of antipsychotic agents that produce hyperprolactinemia and secondarily lower estrogen and testosterone levels. This potential complication of treatment with certain antipsychotic agents requires careful study and could represent a serious public health problem.

Bone alterations in children with idiopathic hypercalciuria at the time of diagnosis

Some children with idiopathic hypercalciuria (IH) develop bone alterations at some stage of the disease. The aims of this study were to evaluate bone mass in 88 children with IH (G1) at the time of diagnosis and to compare the findings with data for a control group of 29 normal children (G2). Kidney and bone metabolism markers were measured in both groups, and bone densitometry was performed. Serum alkaline phosphatase, intact parathyroid hormone, urinary calcium and uric acid were significantly higher in G1, whereas urinary volume and urinary citrate excretion were lower. The following densitometric parameters were significantly lower in G1: (1) lumbar spine (L(2)-L(4)) bone mineral density (BMD), bone mineral content (BMC), BMC corrected for height and for width of the vertebra, volumetric BMD (BMDvol), and Z score; (2) whole-body BMD; (3) femoral neck BMD. Lumbar spine BMDvol was reduced (osteopenia) in 35% of the patients compared with G2. N telopeptide, a urinary marker of bone resorption, was significantly higher in G1 than in G2, and was negatively correlated with lumbar spine BMD and BMDvol. Children with urinary lithiasis or idiopathic hyperuricosuria associated with IH showed no significant differences in bone metabolism compared with children without these associations. We conclude that (1) there is an altered bone metabolism in IH, with osteopenia already present at diagnosis in 35% of the patients; (2) N telopeptide is one of the most useful markers of bone alterations in IH, especially at an early stage of the disease; (3) investigation of bone metabolism is necessary in IH to prevent future serious consequences such as osteoporosis and bone fractures.

Endocrine complications in pediatric patients with acute lymphoblastic leukemia

Endocrine complications of therapy for acute lymphoblastic leukemia (ALL) are common and are potentially debilitating both during and after therapy. Growth velocity slows during therapy for ALL, especially during the first year; however, children who do not receive cranial irradiation usually reach normal adult height. While growth hormone deficiency generally occurs in patients who have received 24Gy of cranial irradiation, it may also develop in those treated with lower doses (18Gy) of cranial radiation or with only high-dose methotrexate. Obesity commonly occurs during therapy and persists after completion of therapy. Osteopenia can occur early during therapy for ALL and can persist for many years. Adrenal insufficiency should be suspected in any child who has recently received glucocorticoid therapy, and stress doses of steroid should be administered in the event of metabolic stress. Screening of urine is useful for early detection of hyperglycemia during therapy with glucocorticoids and L-asparaginase. The syndrome of inappropriate secretion of anti-diuretic hormone is usually associated with vincristine therapy and may be aggravated by concurrent use of azole antifungals. Finally, patients who have received 18 or 24Gy of cranial irradiation may have clinical or subclinical deficiencies of thyroid hormones.

Vitamin D status in children, adolescents, and young adults with Crohn disease

BACKGROUND

Crohn disease (CD) and vitamin D deficiency are associated with decreased bone mineralization.

OBJECTIVE

We examined the prevalence of and risk factors for hypovitaminosis D in children, adolescents, and young adults with CD.

DESIGN

Growth, clinical characteristics, vitamin D intake ( micro g/d), and bone mineral density (g/cm(2)) were measured in a cross-sectional study of 112 subjects (44 females) who had CD and were 5-22 y of age. Hypovitaminosis D was defined as a serum concentration of 25-hydroxyvitamin D [25(OH)D] < 38 nmol/L.

RESULTS

The mean (+/- SD) serum concentration of 25(OH)D was 59.7 +/- 26.9 nmol/L, and 16% (95% CI: 9.3%, 23%) of the subjects had hypovitaminosis D. Hypovitaminosis D was most prevalent during the winter (31%; P = 0.02), among the African Americans (56%; P = 0.01), in the subjects with CD confined to the upper gastrointestinal tract (44%; P = 0.05), and in the subjects with a greater lifetime exposure to glucocorticoid therapy (23.7 +/- 13.5 compared with 17.5 +/- 12.2 mg/d; P = 0.05). There was no association between hypovitaminosis D and either bone mineral density (P = 0.10) or average dietary intake of vitamin D (4.6 +/- 3.6 micro g/d; P = 0.87).

CONCLUSIONS

In this sample of pediatric patients with CD, hypovitaminosis D was common and was associated with the winter season, African American ethnicity, CD confined to the upper gastrointestinal tract, and magnitude of lifetime exposure to glucocorticoid therapy. The occurrence of these factors should prompt assessment of 25(OH)D status and clinical care optimized by supplementing subjects who have low serum concentrations. The physiologic relevance of ethnicity on 25(OH)D status in children with CD remains to be determined.

Children who avoid drinking cow milk have low dietary calcium intakes and poor bone health

BACKGROUND

Information concerning the adequacy of bone mineralization in children who customarily avoid drinking cow milk is sparse.

OBJECTIVE

The objective was to evaluate dietary calcium intakes, anthropometric measures, and bone health in prepubertal children with a history of long-term milk avoidance.

DESIGN

We recruited 50 milk avoiders (30 girls, 20 boys) aged 3-10 y by advertisement. We measured current dietary calcium intakes with a food-frequency questionnaire and body composition and bone mineral density with dual-energy X-ray absorptiometry and compared the results with those of 200 milk-drinking control children.

RESULTS

The reasons for milk avoidance were intolerance (40%), bad taste (42%), and lifestyle choice (18%). Dietary calcium intakes were low (443 +/- 230 mg Ca/d), and few children consumed substitute calcium-rich drinks or mineral supplements. Although 9 children (18%) were obese, the milk avoiders were shorter (P < 0.01), had smaller skeletons (P < 0.01), had a lower total-body bone mineral content (P < 0.01), and had lower z scores (P < 0.05) for areal bone mineral density at the femoral neck, hip trochanter, lumbar spine, ultradistal radius, and 33% radius than did control children of the same age and sex from the same community. The z scores for volumetric (size-adjusted) bone mineral density (g/cm(3)) were -0.72 +/- 1.17 for the lumbar spine and -0.72 +/- 1.35 for the 33% radius (P < 0.001). Twelve children (24%) had previously broken bones.

CONCLUSIONS

In growing children, long-term avoidance of cow milk is associated with small stature and poor bone health. This is a major concern that warrants further study.

Osteoporosis prevention: pediatricians' knowledge, attitudes, and counseling practices

BACKGROUND

Strategies to prevent adult osteoporosis are best undertaken during childhood and adolescence, when the greatest amount of bone mineral density is acquired. This study examines pediatricians' knowledge and practices regarding osteoporosis prevention.

METHODS

One hundred eighty-seven primary care pediatricians from San Diego and Imperial Counties responded to a 44-item mailed survey that measured physician knowledge, attitudes, and practices regarding osteoporosis prevention.

RESULTS

Knowledge of U.S. RDA for calcium in children and adolescents was limited, with only 23.7 and 32.3% of pediatricians correctly identifying the recommended values for children and adolescents, respectively. Thirty-eight percent of respondents regarded osteoporosis prevention to be an important issue, and less than half reported that they counseled patients for osteoporosis prevention. Of those pediatricians who did perform osteoporosis counseling, the two most frequently cited motivators for counseling were that counseling is recommended by professional boards and having a personal or professional interest in osteoporosis prevention. The most commonly reported barriers to counseling were other issues taking greater priority and having insufficient time to undertake counseling for osteoporosis prevention.

CONCLUSIONS

Osteoporosis prevention should begin in childhood and adolescence. This study suggests that many pediatricians do not counsel patients to reduce osteoporosis risk, nor do they consider this an important issue. Furthermore, they may not have full knowledge about how to prevent osteoporosis.

Fast food restaurant use among adolescents: associations with nutrient intake, food choices and behavioral and psychosocial variables

OBJECTIVE

To examine demographic, behavioral and dietary correlates of frequency of fast food restaurant use in a community-based sample of 4746 adolescent students.

DESIGN

A survey was administered to students in classrooms at 31 secondary schools in a large metropolitan area in Minnesota, United States. Height and body weight were measured.

SUBJECTS

Students in grades 7-12 who were enrolled in participating schools, had parental consent and were in attendance on the day of data collection.

MEASUREMENTS

Frequency of fast food restaurant use (FFFRU), dietary intake, and demographic and behavioral measures were self-reported. Dietary intake was assessed using a semi-quantitative food frequency questionnaire. Height and body weight were directly measured.

RESULTS

FFFRU was positively associated with intake of total energy, percent energy from fat, daily servings of soft drinks, cheeseburgers, french fries and pizza, and was inversely associated with daily servings of fruit, vegetables and milk. FFFRU was positively associated with student employment, television viewing, home availability of unhealthy foods, and perceived barriers to healthy eating, and was inversely associated with students' own and perceived maternal and peer concerns about healthy eating. FFFRU was not associated with overweight status.

CONCLUSIONS

FFFRU is associated with higher energy and fat intake among adolescents. Interventions to reduce reliance on fast food restaurants may need to address perceived importance of healthy eating as well as time and convenience barriers.

Ultrasound parameters of calcaneal bone density in girls with anorexia nervosa

Osteoporosis is common in patients with anorexia nervosa (AN), but ultrasound has so far been scarcely used to detect it We measured calcaneal broadband ultrasound attenuation (BUA) and velocity of sound (VOS) in 26 AN girls (mean age 15.1+/- 1.5 years) using a Cuba Clinical device (McCue Ultrasonics, UK). Basic anthropometric (body weight, height and body mass index--BMI) and clinical data (mean duration of AN, number of absent cycles, weight loss) were collected. All of the girls reported that they did at least one hour's vigorous exercise a day. BUA was significantly lower (p<0.004) and VOS significantly higher (p<0.0001) in comparison with reference data. Body weight and BMI at the time of the measurements were significantly lower than the reference data (p<0.0001). There were no correlations between body weight or height and BUA or VOS, but there was a slight correlation between BUA and BMI (r=0.4, p<0.05) and a slight inverse correlation between VOS, body weight and BMI (r=-0.48 and r=-0.43, p<0.01). VOS slightly correlated with weight loss (r=0.4, p<0.05), significantly with the weekly number of exercise hours (r=0.48, p<0.01). The duration of AN, the number of missed cycles and the percentage of weight loss did not correlate with BUA, and neither the duration of AN nor the number of missed cycles correlated with VOS. The low BUA value could be attributed to poor nutrition, and substantial physical activity may lead to the increase in VOS. In conclusion, girls with AN have low BUA and high VOS values, neither of which correlate with the duration of AN or the number of missed cycles.

Lower femoral neck bone mineral density in prepubertal former preterm girls

The purpose of this case-control study was to determine bone mineral content and areal bone mineral density at various skeletal sites in former preterm girls, aged 7-9 years, and to compare these data with age-matched term controls. Subjects included 25 white, prepubertal, former preterm girls (gestational age 30.8 +/- 0.3 weeks, birthweight 1461 +/- 56 g [mean +/- SEM]). Controls included 50 healthy, white, prepubertal girls born at term and matched for age (two controls per case). Measurements included anthropometric variables, calcium intake according to a food-frequency questionnaire, bone mineral content (BMC; grams), and areal bone mineral density (aBMD; grams per square centimeter), using dual-energy X-ray absorptiometry (DXA) at six skeletal sites. Thirteen preterm girls and 13 age-matched term controls were reassessed 1 year after the first DXA measurement. The former preterm girls were similar to controls in terms of age and height, but were lighter (24.6 +/- 0.6 vs. 27.0 +/- 0.6 kg, p = 0.02). They also reported a higher median calcium intake (1058 vs. 759 mg/day, p = 0.004). aBMD was lower in former preterms compared with controls at the level of the radial metaphysis (0.283 +/- 0.006 vs. 0.298 +/- 0.004, p = 0.04), femoral neck (0.593 +/- 0.011 vs. 0.638 +/- 0.010, p = 0.007), and total hip (0.596 +/- 0.012 vs. 0.640 +/- 0.010, p = 0.007), but was similar between the two groups at the radial diaphysis (0.437 +/- 0.004 vs. 0.436 +/- 0.004) and femoral diaphysis (1.026 +/- 0.015 vs. 1.030 +/- 0.011). Femoral neck aBMD remained lower compared with controls in the subgroup of preterm girls reassessed after 1 year (0.608 +/- 0.017 vs. 0.672 +/- 0.020, p = 0.02). In random effects models for longitudinal data, taking into account the effects of age, weight, and height on aBMD (dependent variable), femoral neck aBMD remained lower in former preterms (p < 0.001). Prepubertal former preterm girls showed growth recovery, but had lower aBMD at the hip and radial metaphysis than age-matched term controls, despite spontaneously higher calcium intake. Preterm girls had similar aBMD results compared with controls at sites with predominantly cortical bone (radial and femoral diaphysis), which are known to be more sensitive to calcium intake.

Severe osteopenia in a young boy with Kostmann's congenital neutropenia treated with granulocyte colony-stimulating factor: suggested therapeutic approach

Kostmann's syndrome is a congenital disorder that causes an impairment of myeloid differentiation in the bone marrow characterized by severe neutropenia, which can be treated with recombinant human granulocyte colony-stimulating factor (G-CSF). We present the case of a 13-year-old boy with Kostmann's syndrome who was treated with recombinant human G-CSF from age 3.5 years. His growth and development was normal, although complicated by intermittent infections. Bone mineral density (BMD) measurement revealed severe osteopenia at the spine and hips (lumbar spine BMD 0.486 g/cm(2); Z score -3.6), and he was referred to the Endocrine Service. Relevant laboratory evaluation showed a pretreatment ionized calcium level at the upper limit of normal (1.28 mmol/L; range: 1.13-1.32 mmol/L), suppressed intact parathyroid hormone (iPTH) level (12 pg/mL; range: 10-65 pg/mL), and a low 1,25-dihydroxy vitamin D level (21 pg/mL; range: 24-65 pg/mL). He had evidence of increased bone turnover evidenced by elevated urinary deoxypyridinoline (DPD) cross-links (46.9 nmol/mmol creatinine; range: 2-34 nmol/mmol creatinine) and a simultaneous increase in markers of bone formation with elevated osteocalcin level (200 ng/mL; normal: 20-80 ng/mL) and alkaline phosphatase level (236 IU/mL; normal: 38-126 IU/mL). Because of clinical concern for his skeletal health, bisphosphonate therapy with intravenous pamidronate was initiated. One month after treatment, the iPTH and DPD cross-links were in the normal range (54 pg/mL and 17.7 nmol/mmol creatinine, respectively) and the 1,25-dihydroxy vitamin D level was elevated (111 pg/mL). Four months after treatment, there was a striking increase in BMD at the lumbar spine (+30.86%), femoral necks (left, +20.02%; right, +17.98%), and total hips (left, +18.40%; right, +15.94%). Seven months after bisphosphonate therapy, his biochemical parameters showed a return toward pretreatment levels with increasing urinary DPD cross-links (28.7 nmol/mmol creatinine) and decreasing iPTH (26 pg/mL). However, the BMD continued to increase (8 months posttreatment), but the magnitude of the increment was attenuated (lumbar-spine, +4.8%; left total hip, +1.2% and right total hip +2.4%), relative to BMD at 4 months. Eight months after the initial treatment, his iPTH was suppressed at 14 pg/mL and he again received pamidronate (at a lower dose); 3 months later, he had an additional increase in BMD (lumbar spine +7.4%, left total hip +3.9%, right total hip +2.7%), relative to the previous study. We hypothesize that prolonged administration of G-CSF as treatment for Kostmann's syndrome is associated with increased bone resorption, mediated by osteoclast activation and leading to bone loss. In children, the resulting osteopenia can be successfully managed with antisreorptive bisphosphonate therapy with significant improvement in bone density. Measurements of biochemical parameters of bone turnover can be used to monitor the magnitude and duration of the therapeutic response and the need for BMD reassessment and, perhaps, retreatment.

Calcium metabolism and bone mass in female rabbits during skeletal maturation: effects of dietary calcium intake

This study documents growth and dual-energy X-ray absorptiometry (DXA)-determined peak bone mass profiles in the rabbit model, and tests the hypothesis that rabbits show patterns of bone accretion similar to humans and thus may serve as a viable model for human bone physiology. It is also shown that dietary Ca intake affects peak bone mass and the temporal pattern of its attainment. Groups of weaned animals were administered two nutritionally complete but calcium-altered diets (0.5% or 1.0% Ca). We evaluated growth, bone mass accretion, and Ca metabolism from 20 to 56 weeks of age in both the 1.0% Ca and 0.5% Ca groups of rabbits. For each monthly period, we monitored body mass, naso-tail length, food consumption, and fecal output. In addition, we collected blood and 24 h urine samples for biochemical analyses, and measured bone mass variables of the lumbar spine with DXA. The 1.0% Ca group had a lower apparent fractional absorption of Ca and higher urinary Ca excretion, but retained more Ca than the 0.5% Ca group during the growth phase. Furthermore, the 1.0% Ca group had lower parathyroid hormone (PTH) and bone biochemical marker concentrations throughout the study than the 0.5% Ca group. The lower levels of PTH and bone markers of resorption and formation, may have resulted in a reduction in skeletal remodeling, and this physiological mechanism may have contributed to the 10% increase in peak bone mineral density of the lumbar spine in the 1.0% Ca group of rabbits.

Calcium intake and bone mass development among Israeli adolescent girls

OBJECTIVE

To determine the possible relationship between food and life style habits and bone health in adolescent Israeli females.

METHODS

2,000 adolescent Israeli Jewish and Arab high-school girls (mean age 14.5) completed a semi-quantitative food frequency questionnaire and a personal history questionnaire. 27 food components were calculated for each subject. Bone mineral content and density were determined for 112 subjects with calcium intake below 800 mg/day.

RESULTS

Average calcium intake was found to be 1,260 mg/day, but 20% of all girls had a calcium intake below 800 mg/day. All low-energy diets were very low in calcium, as mean calcium intake per 1,000 calories was 411 128 grams. A large percentage of diets with less than 800 mg calcium were also deficient in phosphorus (95.2%), magnesium (84.8%). iron (90.5%) and zinc (100%). Due to differences in food sources. Jewish girls had more phosphorus in their diet, but less magnesium and iron compared to Arab girls. Calcium and zinc deficiencies in Jewish and Arab diets were similar. A negative correlation was found between body mass index (BMI) and age at menarche for all girls in the study. Bone mineral density (BMD) measured for girls with calcium intake below 800 mg/day distributed normally around the average when compared to age matched controls despite their low calcium intake. There was a strong positive correlation between BMD and bone mineral content (BMC) at all sites and body weights.

CONCLUSIONS

Low calcium intake, other nutritional deficiencies and delayed menarche due to low-energy diet in the growing period and in adolescence may prevent the formation of healthy bones. There is no evidence of lower bone mass among the low calcium intake group in the study population at this stage. It remains to be documented if the window of opportunity for optimal bone accretion for this group will be missed in the future. possibly leading to increased risk of osteoporosis.