Measurement of bone mineral density by dual energy X-ray absorptiometry in preterm infants fed human milk or formula

Bone mineralization of healthy preterm infants fed human milk were compared with that of similar fed preterm formula. Bone mineralization was studied by dual energy X-ray absorptiometry in 43 preterm infants divided into two groups; 21 preterm infants were fed with maternal breast milk and 22 preterm infants with a preterm formula containing 70 mg calcium and 35 mg phosphorus per decilitre. Conclusion Preterm infants fed breast milk had lower bone mineral density than the preterm formula-fed group. Fortifying preterm human milk with calcium and phosphorus will improve bone mineralization in preterm infants. Received: 26 November 1996 and in revised form: 26 August 1997 / Accepted: 9 September 1997     

Bone mineralisation in ex-preterm infants aged 8 years

In preterm infants, in whom perinatal mineralisation deficits are common, there is little information on long-term bone mineralisation. Using a Hologic QDR 1000 dual energy X-ray absorptiometer, bone mineral content and density (BMC and BMD) were measured in lumbar, spine, forearm and hip in 46 ex- preterm infants <32 weeks gestation together with controls at 8 years of age. Height and weight were recorded, as was history of bone fracture. Preterm infants were shorter by 4.9 cm (95% CI, 2.4 – 7.3) and lighter by 2.6 kg (95% CI, 0.7 – 4.4). BMC for all sites measured was significantly lower in the preterm group, but did not remain so when adjusted for height and weight. BMD was significantly reduced in the hip of the preterm group. Prolonged ventilation was associated with the lowest BMC and duration of preterm formula feeding correlated with higher BMC. Accidental fractures were less common in the preterm group. Conclusion Ex preterm infants have significant reduction in bone mineral mass commensurate with their reduced growth and reduced bone mineral density in their hips. Received: 16 June 1997 / Accepted in revised form: 16 May 1998     

早产婴儿骨密度及其影响因素分析

目的：了解早产儿骨矿发育的情况及影响因素。方法：随机选取儿保门诊随访的早产儿与足月儿各90例,采用定量超声技术测量6月龄时（早产儿为纠正胎龄6月龄）的胫骨骨密度,结果以超声波声速度（SOS）值和Z值表示;同时采用回顾性问卷调查影响骨矿发育的相关因素。结果：足月儿6月龄的SOS值和Z值明显高于纠正胎龄6月龄的早产儿。在早产儿组中,不同出生体重、胎龄婴儿的SOS值和Z值,不同断母乳时间婴儿的SOS值差异有统计学意义（P<0.05）;早产儿女婴的Z值明显高于男性婴儿,差异有统计学意义(P<0.05)。多元线性回归分析显示,断母乳时间及每天户外活动时间是早产婴儿SOS值的影响因素。结论：适时断母乳或延长每天户外活动时间可能有利于促进早产婴儿骨矿发育。     

Reproducibility of DXA measurements of bone mineral density and body composition in children

Background  The technique of X-ray-based dual photon absorptiometry (DXA) is frequently used in children for the detection of changes in bone mass or body composition. Such changes can only be considered real if the uncertainties arising from the measurement technique are exceeded. Objective  Our objectives were twofold: (1) to determine the reproducibility of bone mineral density (BMD) measurements in children at the spine and the hip and from the whole body, as well as of whole-body measurements of mineral mass, lean body mass and fat mass in children; and (2) to estimate, from the measured precision, the time interval that needs to elapse before a statistically significant change in a DXA variable can be detected. Materials and methods  The reproducibility of techniques for the measurement of BMD and body composition using DXA was measured in 15 young children (9 girls and 6 boys) and 17 older children (9 girls and 8 boys). Results  Reproducibility was derived from the standard deviation of three repeated measurements of spine BMD, total hip BMD, whole-body BMD (WBBMD), whole-body bone mineral content (WBBMC), lean mass and fat mass. Technique precision was better than 0.01 g cm⁻² for spine BMD and for WBBMD. Hip BMD measurements were slightly less precise, particularly in younger children (0.013 g cm⁻²). For body composition variables, technique precision was 13 g for WBBMC, 201 g for lean body mass and 172 g for fat mass in younger children. Technique precision for older children was 18 g, 251 g and 189 g for the corresponding variables. Predictions showed that the absence of a normal increase in WBBMC in a small-for-age girl could be established after 12 months. For spine BMD, a significant increase should be observable after 6 months for boys over the age of 11 years. For younger boys, more than 12 months has to elapse before anticipated changes can be detected with confidence. Conclusion  The time intervals required to elapse before decisions can be made concerning the significance of observed differences between successive measurements of BMD or body composition in children depend upon the age of the child.     

The potential of digital X-ray radiogrammetry (DXR) in the assessment of osteopenia in children with chronic inflammatory bowel disease

Background Loss of bone mass is a known complication of chronic inflammatory bowel disease (IBD) in children. The gold standard in the evaluation of bone mineral density (BMD) is dual energy X-ray absorptiometry (DXA). Objective In this preliminary study we evaluated digital X-ray radiogrammetry (DXR) which estimates BMD (DXR-BMD) from hand radiographs in children with IBD. Materials and methods A total of 26 children with IBD (10 girls, 16 boys; age range 10–18 years) underwent DXR for the calculation of DXR-BMD and metacarpal index (DXR-MCI) using the Pronosco X-posure system. The results were compared with a local reference database and correlated with the results of DXA. Results DXR-BMD was 0.36–0.56 g/cm² (median 0.46 g/cm²) in Crohn disease patients and 0.38–0.63 g/cm² (median 0.48 g/cm²) in ulcerative colitis patients. DXR-MCI was 0.29–0.49 in Crohn disease patients and 0.28–0.53 in ulcerative colitis patients. The Z-scores were reduced to <−1 SD in five Crohn disease patients and in six ulcerative colitis patients. The coefficients (r) for the correlations between DXR-BMD and DXA-BMD were 0.78 for the lumbar spine and 0.61 for the proximal femur (P<0.01), and between DXR-MCI and DXA-BMD were 0.78 for the lumbar spine and 0.51 for the proximal femur (P<0.01). Conclusions DXR seems to be able to estimate cortical osteopenia in children with chronic IBD. The DXR results showed a positive correlation with DXA results.     

Lumbar bone mineral content measured by dual energy X-ray absorptiometry in newborns and infants

Dual energy X-ray absorptiometry (DXA), a non-invasive method for measuring small amounts of mineral, was used to assess the bone mineral content (BMC) and bone mineral density (BMD) of the lumbar spine (5 vertebrae) in 57 newborns (on day 1-2) and 22 infants (1-24 months of age). A modified high-resolution program (Hologic) allowed us to assess BMC and BMD with a precision higher than 2.4% and 1.5%, respectively. In newborns, BMC and BMD correlated positively with birth weight, body area, length and gestational age: r = 0.73, 0.71, 0.63 and 0.60, respectively, for BMC; and r = 0.59, 0.58, 0.54 and 0.53, respectively, for BMD. In infants, both BMC and BMD were highly correlated with weight, age, length and body area over two years (r = 0.94 or better in each instance). The data provide normal values for lumbar spine BMC and BMD in newborns (gestational age 31-40) and infants up to two years of age; DXA appears to be an excellent and safe tool for pediatric bone mineral measurements.     

Bone mineral density in adolescent females treated withl-thyroxine: a longitudinal study

It has been suggested that chronic treatment withl-thyroxine (l-T4) could be implicated in reducing bone mineral density (BMD). The purpose of this longitudinal study was to determine whether appendicular and axial BMD is decreased byl-T4 treatment in adolescent girls. Thirteen adolescent girls with subclinical hypothyroidism caused by chronic lymphocytic thyroiditis were enrolled in the study at the median age of 13.4 years (range 9.2–18.1 years).l-T4 was administered in a single dose of 1–5 g/kg daily. BMD was evaluated at the distal one-third of the non-dominant radius by single photon absorptiometry (SPA) and at the lumbar spine (L2–4) by dual energy X-ray densitometry (DEXA). Osteocalcin levels were measured to assess bone turnover before and duringl-T4 treatment. Before the start of therapy, mean BMD at both the radial and lumbar level was not significantly different from that of a control group (median age 13.0 years; range 9.0–18.5 years). Duringl-T4 therapy for 2–5 years, BMD did not change at any site. Before treatment, osteocalcin levels were not significantly different from those of controls and did not change during follow up.Conclusion Long-terml-T4 therapy in adolescent girls has no adverse effect on BMD and bone turnover. Our data indicate that attainment of peak bone mass is not impaired byl-T4 administration.     

Bone mineral density in children with neurofibromatosis 1

AIM: Our aim was to detect the status of bone mineral density (BMD) in children with NF1, and thus to help the management of the skeletal complications of NF1. METHODS: Dual-energy X-ray absorptiometry (DEXA) was performed in lumbar spine, total body, proximal femur and forearm in 31 children (3.1-18 years) with NF1. Correlations among the BMD values of four regions were calculated statistically. Z-scores of lumbar- and total body-BMD were also evaluated in 24 patients at and older than 5 years. RESULTS: Eleven children had skeletal findings, including mild scoliosis in 5 patients. No case with total body-Z score <-2 was detected. Lumbar-Z score was lower than -2 in 3 out of 24 cases. Patients with any skeletal involvement of NF1 were likely to have a lumbar-BMD lower than -2 in comparison with patients with no skeletal finding (odds ratio 4; 95% CI 0.01-4.62). Proximal femur-BMD values (g/cm(2)), yet forearm-BMDs, were correlated with both lumbar- and total body-BMD, regardless of skeletal involvements of NF1. CONCLUSIONS: Our findings suggest that lumbar- or proximal femur-DEXA, rather than forearm- or total body-DEXA, could reveal significantly decreased BMD in children with NF1, especially in those with skeletal involvement of NF1.     

Bone mineral density in patients with phenylketonuria

Dual energy X-ray absorptiometry was performed in 44 patients with phenylketonuria (PKU) aged 6-29 y. The phenylalanine-restricted diet was based on a low-protein diet in combination with phenylalanine-free amino acid mixtures and phenylalanine-low casein hydrolysate in 32 patients. The 10 oldest patients were supplemented only with casein hydrolysate, and the youngest child received only the amino acid mixture. One patient has recently come off the diet. Bone mineral density (BMD) of the lumbar spine and total BMD were measured and expressed as Z-score, i.e. the difference between the BMD of the patient and the average BMD of sex- and age-matched controls divided by the standard deviation of the control group. Normal BMD was found in 24 (54%) patients. Lumbar spine BMD was decreased in 20 patients and total BMD was decreased in 14 patients. Z-scores of -1to 2.5 were found in 14 patients (32%) and Z-scores of <-2.5 in 6 patients (14%). No significant correlation was found between total or lumbar spine BMD and daily intake of phenylalanine from natural sources in the low-protein diet or the amount of phenylalanine-free amino acid mixtures per kg of body weight. A significant negative correlation was observed between both total and lumbar spine BMD Z-scores and the amount of casein hydrolysate supplementation per kg of body weight (r = - 0.45; y = 0.07 - 0.69x; p < 0.01). Long-lasting dietary restriction in patients with PKU may increase the risk of late complications of dietary therapy, such as osteoporosis or trace element deficiency. O Bone mineral density, osteoporosis, phenylalanine-low diet, phenylketonuria     

口服双歧杆菌对极低出生体重儿免疫功能的影响

目的：探讨口服双歧杆菌对极低出生体重儿免疫功能的影响。方法：将50例住院极低出生体重儿随机分为观察组和对照组（n=25）。观察组在一般治疗的基础上给予口服双歧杆菌14 d,观察临床指标和外周血相关免疫学指标。结果：观察组需生理盐水灌肠次数较对照组明显减少(P0.05)。观察组外周血CD4+T细胞比例和CD4+/CD8+比值高于对照组(P0.05);观察组外周血IgA水平高于对照组(P0.05)。结论：双歧杆菌可以改善极低出生体重儿的消化道症状,促进极低出生体重儿免疫功能的成熟和发展。     

Bone mineral metabolism changes in epileptic children receiving valproic acid

OBJECTIVE: The aim of this study was to evaluate bone mineral density (BMD) in epileptic children receiving valproic acid (VPA) and to determine differences between osteopenic and non-osteopenic children. METHODS: Thirty-three epileptic children, receiving VPA for at least 6 months, were compared with 33 healthy children for BMD. BMD was measured by dual-energy X-ray absorptiometry at lumbar vertebrae, femoral neck and greater trochanter. Serum calcium, phosphorus, alkaline phosphates, osteocalcin and VPA levels were also determined. RESULTS: Patient's osteocalcin levels were significantly higher (P = 0.02) and femur and trochanter BMD values were significantly lower (P = 0.04 and P = 0.03, respectively). Duration of VPA therapy was significantly longer and doses of VPA were significantly higher in seven osteopenic patients compared with 26 non-osteopenic patients. Osteopenic patients (4.6 +/- 2.4 years) were younger than non-osteopenic patients (7.8 +/- 3.2 years) (P = 0.01). CONCLUSION: Long-term and high dose VPA therapy may cause osteopenia, primarily in younger epileptic children. These patients should be followed closely by BMD measurements.     

Reference values for bone mineral density in 12- to 18-year-old girls categorized by weight,race, and age

Background: Normative bone mineral density (BMD) values for adults do not apply to the pediatric population because of dramatic and variable rates of bone mineral acquisition that take place throughout adolescence. Objective: This study was designed to provide normative BMD values for the lumbar spine and femoral neck by age, weight, and race in female adolescents for use by clinicians. Materials and methods: The study population comprised 422 healthy adolescent girls aged 12–18 years recruited from four primary-care clinics. BMD measurements were performed with dual-energy X-ray absorptiometry (DEXA). Results: The major statistical predictors of lumbar spine BMD and femoral neck BMD were race, chronological age, and weight. There was an increase in both lumbar spine and femoral neck BMD that paralleled an increase in age and weight. In addition, the lumbar spine BMD and the femoral neck BMD were higher in the black participants than in the non-black participants with mean BMD values in grams per centimeter squared of 1.02 and 0.98, respectively, for blacks and 0.96 and 0.89, respectively, for non-blacks (P<0.001). Conclusion: Our study produced the largest set of lumbar spine and femoral neck BMD normative values for female adolescents and confirms the importance of both demographic and anthropomorphic variables in determining normative BMD values.This work was performed at MetroHealth Medical Center, Case Western Reserve University, School of Medicine.     

Comparison between broad-band ultrasound attenuation of the calcaneum and total body bone mineral density in children

We measured broad-band ultrasound attenuation (BUA) in the calcaneum using the prototype Paediatric Contact Ultrasound Bone Analyser (CUBA) and total body bone mineral density (TBBMD) using dual-energy X-ray absorptiometry (DXA) (Hologic QDR-1000W) in 58, 7 17-year-old healthy children and adolescents. Calcaneal BUA was significantly related to TBBMD ( r = 0.74, p < 0.001), and both the calcaneal BUA and TBBMD were significantly correlated with age and body weight. We conclude that calcaneal BUA reflects bone mineral density (BMD) in healthy children and adolescents; however, BMD measured by CUBA appears to be less sensitive than that measured by DXA. Since BUA reflects structural properties of bone, as well as density, it may complement radiological techniques of bone density measurement in the assessment of paediatric conditions associated with fracture risk.     

Bone mineral density is reduced in brain tumour patients treated in childhood

AIM: To determine the prevalence of low bone mineral density among children surviving brain tumours and to identify possible factors underlying impaired bone health. METHODS: Cross-sectional study; total body bone mineral density (TBBMD), fat mass (FM) and lean body mass (LBM) were measured by dual-energy X-ray absorptiometry (DXA) in 46 brain tumour patients aged from 3.8 to 28.7 y (mean 14.9 y) treated in childhood 1.4-14.8 y (mean 6.4 y) after end of treatment for brain tumour. Low bone mineral density was defined as TBBMD z score < - 2.0. RESULTS: Fifteen patients had TBBMD z scores < - 2.0, indicating a 33% prevalence of low bone density. The TBBMD z score ranged from -5.7 to 0.6 (mean -1.7). Out of several potential factors, only combined craniospinal irradiation was significantly associated with low z score (p=0.034, according to multiple regression analysis), while exclusive cranial irradiation showed a borderline statistical association (p=0.100, according to multiple regression analysis). CONCLUSION: One third of brain tumour patients treated in childhood had reduced bone mineral density. The reasons for this condition are apparently multifactorial, including craniospinal irradiation.     

Determinants of bone mineral density in prematurely born children aged 6–7 years

The aim of this study was to assess the long-term effects of prematurity and growth during the first year on bone mineralization in prematurely born children. The study group consisted of 38 prematurely born Finnish children (17M, 21F) examined at the age of 6-7 y. After birth, all children were fed with banked human milk until discharge from hospital. Thereafter, 27 children were partially breastfed until the age of 5–7 months. Infants with gestational age (GA) <33 weeks ( n = 25) received calcium 45-50 mg/100 kcal, phosphorus 40-45 mg/100 kcal, vitamin A 1000 IU/d, vitamin C 2 mg/d and vitamin D 400 IU/d until 2.5 kg. Infants born > 33 weeks received only vitamin D 400 IU/d. Bone mineral density (BMD) and bone mineral content (BMC) were measured by dual energy X-ray absorptiometry (DXA) of the lumbar spine (L2-L4) at 6-7 y of age. At examination, all children had normal height and weight. BMD values were within the confidence interval of the Finnish reference values. In regression analysis bone area, present weight, GA and weight at 1 y were the most significant factors explaining 77.1% of the variance of BMC. After adjusting for other independent variables the prematurely born children who were thinner at 1 y of age subsequently had higher BMC values when examined at the age of 6-7 y. This study shows that growth patterns during the first year of life have long-term effects on bone mineralization.     

Update on Cystic Fibrosis-Related Bone Disease: A Special Focus on Children

A high prevalence of low bone mineralization is documented in adult patients with cystic fibrosis (CF). Osteopenia is present in up to 85% of adult patients and osteoporosis in 10% to 34%. In children, study results are discordant probably because of comparisons to different control populations and corrections for bone size in growing children. Malnutrition, inflammation, vitamin D and vitamin K deficiency, altered sex hormone production, glucocorticoid therapy, and physical inactivity are well known risk factors for poor bone health. Puberty is a critical period for bone mineralization and requires a careful follow-up to achieve optimal bone peak mass. Strategies for optimizing bone health, such as monitoring bone mineral density (BMD) and providing preventive care are necessary from childhood through adolescence to minimize CF-related bone disease in adult CF patients.     

Soft tissue density variations in thalassemia major: a possible pitfall in lumbar bone mineral density measurements by dual-energy X-ray absorptiometry

Osteoporosis is common in patients with thalassemia major. A 16-year-old patient with thalassemia major was referred for evaluation of osteoporosis. The results of dual-energy X-ray absorptiometry in a patient with thalassemia major are presented. The patient underwent measurements of the spine in both AP and lateral position. The DXA scan of the spine in AP projection showed diffusely increased density overlying the lower thoracic and upper lumbar vertebrae. The overall density of L₂-L₄ was 0.6465 g/cm² (4.93 SD as compared with young adults). The DXA scan of the spine in lateral projection showed diffusely increased density in front part of the spine. The BMD of the L₃ vertebra was 0.3669 g/cm² (0.30 SD as compared with young adults). It is important to interpret the images visually in order to obtain true values of BMD, and preclude invalid BMD measurements.     

Bone mineral density and metabolism in children with congenital hypothyroidism after prolonged l-thyroxine therapy

Abstract The effect of long-term l -thyroxine (LT4) replacement therapy on bone mineral density and on biochemical markers of bone turnover were studied in children with congenital hypothyroidism (CH). Forty-four children and adolescents (mean age 8.5 ± 3.5 years) with primary CH who began LT4 replacement therapy within the first month of life were studied. Bone mineral density (BMD) of the lumbar vertebrae and the upper femoral bone was measured by dual energy X-ray absorptiometry. Serum osteocalcin (OC) and bone alkaline phosphatase were measured as markers of bone formation and urinary deoxypyridinoline was taken as a marker of bone resorption. Bone mineral densities of CH children were not different from those in age-matched controls. The biochemical markers of bone turnover were normal except for the serum OC levels which were found to be higher than in controls and positively correlated with the free thyroid hormone levels (for FT4 r = 0.42, p = 0.02). Eight CH children demonstrated low BMD values (below -1 SDS) at - 2 ± 0.7 SDS for the lumbar spine and - 1.6 ± 0.5 SDS for the femoral site. These eight children showed lower mean weight ( p < 0.05) and their dietary calcium intake tended to be less ( p < 0.06) than that seen in the normal BMD group. In conclusion, our results show that LT4 replacement therapy for 8 years is not detrimental to the skeletal mineralization of CH children. As in a healthy population, weight and current intake of calcium seem to be major determinants of bone density. Dietary recommendations, especially when calcium intake is below the recommended dietary allowance, may have to be reconsidered.