Total body water reference values and prediction equations for adults

BACKGROUND: The clinical interpretation of total body water (TBW) necessitates the availability of timely comparative reference data. The prediction of TBW volume in renal disease is critical in order to prescribe and monitor the dose of dialysis in the determination of Kt/V. In clinical practice, urea distribution (V) is commonly predicted from anthropometric equations that are several decades old and for white patients only. This article presents new reference values and prediction equations for TBW from anthropometry for white and black adults. METHODS: The study sample included four data sets, two from Ohio and one each from New Mexico and New York, for a total of 604 white men, 128 black men, 772 white women, and 191 black women who were 18 to 90 years of age. The TBW concentration was measured by the deuterium or tritium oxide dilution method, and body composition was measured with a Lunar DXA machine. An all-possible-subsets of regression was used to predict TBW. The accuracy of the selected equations was confirmed by cross-validation. RESULTS: Blacks had larger TBW means than whites at all age groups. The 75th TBW percentile for whites approximated the TBW median for blacks at most ages. The white men and black men and women had the largest TBW means ever reported for healthy individuals. The race- and sex-specific TBW prediction equations included age, weight, and stature, with body mass index (BMI) substituted for weight in the white men. The root mean square errors (RMSEs) and standard errors for the individual (SEIs) ranged from approximately 3.8 to 5.0 L for the men and from 3.3 to 3.6 L for the women. In both men and women, high values of TBW were associated with high levels of total body fat (TBF) and fat-free mass (FFM). CONCLUSION:: TBW in these healthy adults is relatively stable through a large portion of adulthood. There are significant race and sex differences in TBW. These accurate and precise equations for TBW provide a useful tool for the clinical prediction of TBW in renal disease for white and black adults. These are the first TBW prediction equations that are specific for blacks.     

Anthropometric and body composition assessment in dialysis patients

Anthropometric and body composition assessments provide important information about the nutritional status of dialysis patients. Anthropometric measurements describe body size, fatness, and leanness in dialysis patients and have been collected in the Modification of Diet in Renal Disease (MDRD) and HEMO studies. Dialysis patients present special problems for anthropometry, including decreased functional status and increased comorbidity, that challenge nutrition assessment methodology. Recumbent anthropometric techniques are recommended and stature is estimated from knee height. Measures of weight, stature, calf circumference, arm circumference, and triceps and subscapular skinfolds have recently been reported for dialysis patients, who tend to be shorter, lighter, and have less adipose tissue than healthy persons of the same age. The HEMO study anthropometric data provide a clinical reference for assessing the nutritional status of dialysis patients. The most common body composition methods used with dialysis patients are dual energy X-ray absorptiometry (DEXA), bioelectrical impedance, total body water (TBW), and prediction equations, but they are not recommended for assessment of predialysis patients, as estimates are best obtained postdialysis. The TBW volume used in calculating the dose of dialysis has commonly been predicted from the limited, out-of-date equations of Watson, based on nonrepresentative samples. New prediction equations are available for white, black, and Mexican American children and adults. Watson's data are not representative of the TBW of U.S. men and women. The greater TBW in non-Hispanic black men and women and Mexican American women reflects the greater levels of obesity in the U.S. population.     

Total body water in children with cystic fibrosis using bioelectrical impedance

BACKGROUND: The aim of this study was to assess the ability of commercially available single frequency bioelectrical impedance analysis (BIA) to predict total body water and hence body composition in a cohort of children with cystic fibrosis (CF). METHODS: In 56 (31 girls, 25 boys) children aged 4 to 18 years, total body water was predicted using BIA and measured using a deuterium oxide dilution technique. Each child provided a urine sample before consuming 0.5 g/kg body weight 10% deuterium oxide. A further urine sample was collected between 4 and 6 h later. RESULTS: There was a mean bias between predicted and measured total body water of 1.1 L. The bias was consistent across the range of total body water measured in this study. The relationship between height2/impedance and measured total body water was TBW=0.35+0.74*height2/impedance. This equation is similar to other equations found in healthy children. CONCLUSION: We have shown that a commercially available bioelectrical device underestimates measured total body water. We have generated a prediction equation for the population studied, which we believe might enhance the accuracy of the method in children with cystic fibrosis.     

Comparing different methods of assessing body composition in end-stage renal failure

BACKGROUND: Accurate measurement of nutritional status in patients with end-stage renal disease is important because of its clear association with prognosis. Total body water (TBW) has additionally been recently recognized as an independent prognostic value because of its relationship with hypertension and cardiac morbidity. The current study was designed to assess the utility of surrogate markers of nutritional state and TBW in patients with end-stage renal disease. METHODS: Fifty-four patients with renal disease were studied. TBW obtained using the deuterium dilution technique was compared with estimates derived from anthropometric measures of TBW, including 58% body weight, Watson equations, and bioelectrical impedance analysis (BIA). Anthropometrically derived fat-free mass (FFM) was compared with BIA-derived estimates. Total body nitrogen (TBN) measurements were correlated with TBW estimates and BIA-derived resistance. RESULTS: TBW was significantly underestimated by the Watson equation (mean difference, -1.751 L, P = 0.01) and the 58% body weight approximation significantly overestimated it (mean difference, 1.792 L, P = 0.04). The Kushner BIA estimation of TBW did not significantly differ from that of the gold standard determined from D2O dilution (mean difference, -1.221 L, P = 0.12) and was also the method that showed the best agreement with the D2O estimate. However, the limits of agreement were large. Accurate prediction equations for FFM (FFM = -21.768 + 0.001 x ht2 + 6630.669 x 1/R + 0.312 x wt, R2 = 0.95) and TBN (TBN = -668.324 - 3.963 x age + 10.133 x wt + 0. 045 x ht2 + 32141.457 x 1/R, R2 = 0.91) were derived from BIA obtained resistance. CONCLUSIONS: The estimation of TBW varies significantly depending on the method of calculation. BIA is the most accurate surrogate marker for the measurement of both TBW and other parameters of body composition.     

Demonstration that bone mass is greater in black than in white children

Osteoporosis and hip fractures are less common and bone mass is greater in black than in white women. To determine if bone mass is greater in black than in white children, bone mineral density (BMD) of the midradius by single-photon absorptiometry and BMD of the lumbar spine (L1-L4), trochanter, and femoral neck by dual-photon absorptiometry were measured in 20 black boys, 18 black girls, 33 white boys, and 35 white girls between the ages of 7 and 12 years. Mean age (10.4 +/- 0.3 versus 10.2 +/- 0.2 years) and body weight (39 +/- 2 versus 38 +/- 2 kg) in the blacks and whites, respectively, were not different in the two groups, and the ages and weights of the boys and girls were not different from each other. BMD were significantly greater in black than in white children at each site, in the black than in white boys at the trochanter and femoral neck, and in the black than in white girls at each site. In both races, BMD varied directly with age and body weight. Multivariate analysis showed that BMD were greater at the midradius, lumbar spine, trochanter, and femoral neck in the black than in the white children, that BMD of the lumbar spine was greater in the girls than in the boys, and that BMD of the trochanter and femoral neck were greater in the boys than in the girls. There were significant partial correlations between race and BMD and between BMD and body weight at each site, between sex and BMD at the lumbar spine, trochanter, and femoral neck, and between age and BMD at the midradius, trochanter, and femoral neck. Race, sex, age, and body weight together accounted for 49-66% of the variation in bone mass. Thus, BMD of the midradius, spine, and hip are greater in black than in white children, body weight and age are important determinants of bone mass, and some sex differences in bone mass are present at this age.     

Perioperative monitoring of total body water by bio-electrical impedance in children undergoing open heart surgery

Knowledge of the changes in total body water (TBW) following cardiac surgery (OHS) in children would be of value in fluid therapy and in researching the causes and management of capillary leak. We have validated a bioelectrical impedance technique (BEI) for non-invasive estimation of TBW in children after OHS. We report the use of this method in a longitudinal study. Twenty patients (mean age 4.7 years +/- 3.5 (SD), mean weight (WT) 16.2 kg +/- 1 kg) undergoing a variety of complex OHS procedures were studied from 1 day preoperatively to 4 days postoperatively. Anaesthetic and basic bypass (CPB) techniques were uniform. Six patients underwent CPB at less than 20 degrees C, 10 at 20 degrees - 25 degrees C and 4 at 26 degrees - 33 degrees C. TBW (BEI), core (ctemp) and peripheral (ptemp) temperatures and fluid balance (TFB) were recorded at frequent intervals. TBW (by BEI) rose (P less than 0.001) following CPB in all patients from 62% +/- 9% (SD) body weight preoperatively to 73% +/- 13% in the ICU (an increase of 11% +/- 5%). TBW remained significantly elevated until the 3rd postoperative day. Multivariate analysis (MVA) confirmed that TBW was significantly related to TFB, but not to ctemp or ptemp. MVA also revealed smaller patient size (height and weight), younger age and longer CPB time as incremental risk factors for the rise in TBW. Conclusions: (1) BEI permits the non-invasive study of TBW in children after OHS, when TBW variation may be considerable. (2) The smaller the child and the longer the CPB, the greater the rise in TBW. (3) The technique should be a valuable tool in researching the major water fluxes associated with CPB in children.     

Ventricular volume change in childhood

OBJECT: The aim of this study was to construct a model of age-related changes in ventricular volume in a group of normal children ages 1 month to 15 years, which could be used for comparative studies of cerebrospinal fluid circulation disorders and cerebral atrophy developmental syndromes. METHODS: A magnetic resonance imaging-based segmentation technique was used to measure ventricular volumes in normal children; each volume was then plotted against the child's age. In addition, intracranial volumes were measured and the ratio of ventricular to intracranial volume was calculated and plotted against age. The study group included 71 normal children, 39 boys and 32 girls, whose ages ranged from 1 month to 15.3 years (mean 84.9 months, median 79 months). The mean ventricular volume was 21.3 cm3 for the whole group, 22.7 cm3 in boys and 19.6 cm3 in girls (p = 0.062, according to t-tests). The mean ventricular volume at 12 months for the whole group was 17 cm3 (20 cm3 in boys and 15 cm3 in girls), representing 65% of the volume achieved by 15 years of age (87% in boys and 53% in girls). The volume increased by a factor of 1.53, to 26 cm3 (23 cm3 in males and 28 cm3 in females, increase factors of 1.15 and 1.86, respectively) at 15 years of age. The change in ventricular volume with age is not linear, but follows a segmental pattern. These age periods were defined as: 0 to 3, 4 to 6, 7 to 10, and 11 to 16 years. A statistical difference based on sex was only demonstrated in the first 6 years of life. The mean ventricular volume for the first 6-year period was 22.4 cm3 in boys and 15.7 cm3 in girls, and the difference was significant for the two sexes (linear regression analysis for age and sex, significant according to analysis of variance regression at 0.007, p = 0.108 for age, p = 0.012 for sex). Thereafter, there was no significant difference in ventricular volume between boys and girls with further growth. The ratio of ventricular volume to intracranial volume was 0.0175 for the whole group, 0.017 in boys and 0.018 in girls (p = 0.272, according to t-tests). At 12 months of age the ratio was 0.019; it stabilized to 0.015 at 8 years of age, and increased to 0.018 at 15 years of age. No statistical difference based on sex was demonstrated with growth. CONCLUSIONS: The ventricular volume in normal children increases with age by a factor of 1.5; the increase is in a nonlinear segmental pattern. Boys have significantly higher ventricular volumes only in the first 6 years of life. The ventricular/intracranial volume ratio remains stable throughout childhood.     

Foot and hand length for prediction of vital capacity in scoliotic children

Expected values of vital capacity (VC) and other lung function variables in children are usually predicted from regression equations of the index test on stature. In children with scoliosis, arm span or an "uncoiled" stature derived from the observed stature and the degree of spinal angulation have been used to predict expected values. Stature and hand and foot length were measured and all three anthropometric indices were used as independent variables for the prediction of VC in 489 normal children and adolescents (aged 4-18 years). VC was highly correlated with stature for boys and girls with regression coefficients of 0.93 and 0.91, respectively. For foot length, corresponding coefficients were 0.90 and 0.83, and for hand length 0.90 and 0.80. In 14 scoliotic children, aged 5.9-18.4 years, a close agreement was found for predictions of VC from arm span, uncoiled stature and hand and foot length. When accurate measurements of stature cannot be made, hand or foot length can be used to predict expected VC. This approach may be an alternative to the use of arm span or uncoiled stature to predict VC in children with scoliosis.     

Microsurgical treatment for hypothalamic hamartoma in children with precocious puberty

BACKGROUND: We review the surgical treatment of hypothalamic hamartoma causing precocious puberty. METHODS: Six children (three girls and three boys) with precocious puberty secondary to hypothalamic hamartoma were recruited for our study. The mean age of the patients was 30 months old (range 13 months to 5 years), and the mean age of the onset of puberty was 7.3 months. All patients were treated by microsurgery. RESULTS: All patients had higher then normal stature, body weight, bone growth, and serum levels of sexual hormones. The boys presented with mature external genitalia, pubic hair, frequent erection, and acne, while the girls presented with growth of breasts and menarche. Magnetic resonance image (MRI) revealed an isointense mass below the tuber cinereum extending into the supersellar and interpeduncular cistern, ranging from 4 to 12 mm in diameter, consistent with pedunculate hamartoma. The hamartoma was removed completely via a right pterional approach. The symptoms and signs of precocious puberty resolved completely, and sexual hormone levels decreased to the pre-pubertal range in all six patients without any postoperative complications. CONCLUSION: We report a series of six children with hypothalamic hamartoma-induced precocious puberty who underwent microsurgical treatment. All of them recovered completely to their age-appropriate state. Microsurgery is a good choice of treatment for pedunculate hypothalamic hamartoma.     

Sex difference of urinary osmolality in German children

BACKGROUND/AIMS: Origin of sex difference in urinary osmolality. METHODS: In 495 healthy children aged 4.0-14.9 years participating in the DONALD (Dortmund Nutritional and Anthropometric Longitudinally Designed) study (247 boys, 248 girls), the water intake recorded in 24-hour weighed dietary records along with urinary volume, osmolality and free water reserve in 24-hour urine samples from the same day as the dietary record were determined. RESULTS: Boys showed a significantly higher energy intake, total water intake, urinary osmolality and osmolar load than girls but no increase in urinary volume. When referred to energy intake, mean urinary volume and mean free water reserve were significantly higher in girls than boys. Girls could have a preference for food with a higher water density and lower non-renal water losses. CONCLUSION: German girls of the DONALD study displayed a lower urinary osmolality than German boys due to a relatively higher urinary volume. The sex difference could be caused by a higher water density of the ingested food (ml/kcal) and a lower insensible water loss (ml/kcal) in girls than boys.     

The development in footprint morphology in 1851 Congolese children from urban and rural areas,and the relationship between this and wearing shoes

The footprints of 1851 Congolese children were studied using the index of Chippaux-Smirak, Staheli's index of the arch, and Clarke's angle. The sample consisted of 906 girls and 945 boys aged between 3 and 12 years, including city children who wore shoes and children from rural areas who had gone barefoot. At the ages of 3 and 4 years, most feet were morphologically flat, but the proportion of flat feet decreased with age in both sexes. Boys had a greater tendency for flat feet. According to the three parameters studied there was a greater proportion of flat feet in the urban environment. By multiple regression analysis the three parameters we had studied identified age as the primary predictive factor for flat feet. As in previous studies in western populations, the girls had a higher inner arch than the boys and footwear had very little influence on the morphology of the foot.     

The evaluation of technetium 99m-citrate scintigraphy in children with suspected appendicitis.

PURPOSE: The authors evaluated the use of technetium (Tc) 99m-citrate scan in 30 children whose diagnoses of appendicitis were unclear. METHODS: There were 17 boys and 13 girls (mean age 10.6 years). Nineteen of 30 patients had appendicitis confirmed at laparotomy and through histological examination, and 11 patients had other causes of acute abdominal pain. RESULTS: Children included in this study were similar with respect to age, duration of symptoms, temperature, white blood cell count, and the incidence of right lower quadrant tenderness. Sixteen children had positive scan for acute appendicitis, but 1 of them had false-positive. Fourteen children had negative scan, but 4 of them had false-negative. The calculated values were 78.9% (15 of 19), 90.9% (10 of 11), 83.3% (25 of 30), 93.7% (15 of 16), and 71.4% (10 of 14) for sensitivity, specificity, accuracy, positive prediction, and negative prediction, respectively, in this study. CONCLUSION: The authors suggest the use of 99mTc-citrate scan in children when the diagnosis of appendicitis using other methods is unclear.     

A longitudinal study of carpal bone development in Perthes' disease: its significance for both radiologic standstill and bilateral disease

This paper reports a longitudinal study of carpal bone development in 125 children (98 boys, 27 girls) attending a clinic for Perthes' disease. The age at appearance of ossification in each carpal bone was estimated by studying consecutive radiographs obtained at six-months intervals. The results were compared with the findings for normal children published by Stuart et al. Three radiologic groups of carpal bone maturation are defined: not delayed (capitate and hamate); markedly delayed (triquetral and lunate); and slightly delayed (scaphoid, trapezium, and trapezoid). Overall, the bone age delay is severely abnormal at three to five years of chronologic age and indicates the time in development when general abnormalities occur. The mean age at diagnosis (and standard deviation) for 34 boys with skeletal standstill was 4.49 +/- 1.07 years, compared with 7.28 +/- 2.40 years for 51 boys without such standstill; the mean age at appearance of carpal bones was not significantly different between these two groups, suggesting an equally profound delay of carpal maturation in the group of later-diagnosed boys. Boys with bilateral hip disease show a significant delay in age at ossification of the trapezoid compared with boys who have unilateral disease. The immaturity of bone age may be present during a latent period and be of etiologic significance in the onset of the hip disease, but at present the evidence links it only with bilateral disease.(ABSTRACT TRUNCATED AT 250 WORDS)     

Percentile distributions of bone measurements in Iowa children: the Iowa Bone Development Study.

Four hundred twenty-eight white children (200 boys and 228 girls) ages 4.5-6.5 yr had spine, hip, and whole-body bone mineral density (BMD) and bone mineral content (BMC) measured by dual-energy X-ray absorptiometry(DXA) as part of the Iowa Bone Development Study. Anthropometric measurements, including height, weight, and body mass index (BMI) were determined for each child at the time the bone measurements were made. The age- and gender-specific height percentile based on the 2000 CDC Growth Charts (www.cdc.gov/growthcharts/) was determined for each child. These percentiles were used to classify children into four groups as defined by the 25th, 50th,and 75th percentile cutpoints. Percentile distributions were determined within each height quartile group to delineate percentiles (5th, 25th, 50th, 75th, 95th) for BMD and BMC. Gender differences in BMD and BMC were investigated before and after stratification into height groups. Boys had higher age-height-weight-adjusted means for most BMD and BMC measures except spine BMD. Bone measurements increased with height quartile, indicating that taller children have greater BMD and BMC compared to shorter children of the same age and gender. Within any given quartile,mean BMD and BMC measurements were similar for boys and girls, with the exception of hip BMD, for which values were consistently higher for boys (p < 0.05). In addition, whole-body BMC values were higher for boys in quartiles 1 and 3 (p < 0.05). These bone measures provide norms for young white children and serve as a reference for comparison with other racial and ethnic groups, as well as with childhood populations that are at risk for osteopenia because of chronic disease. Gender, age, and height are useful clinical predictors of BMD and BMC in young children.     

Growth related hormones in idiopathic scoliosis. An endocrine basis for accelerated growth

In a total of 95 children with idiopathic scoliosis and 60 controls between the ages of 7 and 17 years, a prospective study of hormones related to growth and maturation was carried out. The pituitary release mechanism for growth hormone was evaluated using the propanolol/L-dopa stimulation test. In addition the blood levels of testosterone, sex hormone binding globulin, oestradiol, thyroxin, prolactin, cortisol, follicle stimulating hormone and luteinizing hormone were determined. The girls were divided into age groups and all results were evaluated according to chronological and skeletal age. The number of boys was too small (25) to allow subdivision into age groups. The girls with idiopathic scoliosis had a significantly higher response to the growth hormone stimulation test than had the controls between the ages of 7 and 12 years whereas no significant difference could be found for the older girls. In girls with a skeletal age between 9 and 12 years a significantly higher mean serum level of testosterone was found (P less than 0.05). No significant differences could be demonstrated for the remaining hormones. Growth hormone and testosterone are the most important growth factors in prepubertal and pubertal children. Thus, the present findings suggest a hormonal basis for the increased stature in children with idiopathic scoliosis which has previously been reported.     

Comparisons of body size, composition, and whole body bone mass between North American and South African children.

We compared whole body BMC of 811 black, white, and mixed ancestral origin children from Detroit, MI; Johannesburg, South Africa; and Cape Town, South Africa. Our findings support the role of genetic and environmental influences in the determination of bone mass in prepubertal children. INTRODUCTION: Higher bone mass and lower fracture rates have been shown in black compared with white children and adults in North America. MATERIALS AND METHODS: We compared whole body BMC (WBBMC), whole body fat mass (WBFM), and whole body fat free soft tissue (WBFFST) data between three ethnic groups of children from Detroit, MI (n = 181 white, USW; n = 230 black, USB), Johannesburg, South Africa (n = 73 white, SAW; n = 263 black, SAB), and Cape Town, South Africa (n = 64 mixed ancestral origin, SAM). RESULTS: SAB and SAW groups were slightly older than USW and USB groups (9.5 +/- 0.3 versus 9.3 +/- 0.1 yr); however, USB and USW boys were significantly taller, were heavier, and had a higher BMI than SAM and SAB boys. USB girls were significantly taller than SAB girls and heavier than SAB and SAM girls. In South Africa and the United States, black children had a significantly higher WBBMC than white children, after adjusting for selected best predictors. After adjusting for age, weight, and height, WBBMC was significantly higher in the SAB and SAW boys than in USW and USB and in the SAM group compared with the USW and USB groups. WBFFST and WBFM made significant contributions to a best linear model for log(WBBMC), together with age, height, and ethnicity. The best model accounted for 79% of the WBBMC variance. When included separately in the model, the model containing WBFFST accounted for 76%, and the model containing WBFM accounted for 70%, of the variance in WBBMC. CONCLUSIONS: WBBMC is lower in children of European ancestry compared with African ancestry, irrespective of geographical location; however, South African children have significantly higher WBBMC compared with USB and USW groups, thereby acknowledging the possible contribution of environmental factors. Reasons for the significantly higher WBBMC in the children of mixed ancestral origin compared with the other groups need to be studied further.     

Growth Related Hormones in Idiopathic Scoliosis: An Endocrine Basis for Accelerated Growth

In a total of 95 children with idiopathic scoliosis and 60 controls between the ages of 7 and 17 years, a prospective study of hormones related to growth and maturation was carried out.

The pituitary release mechanism for growth hormone was evaluated using the propanolol/L-dopa stimulation test. in addition the blood levels of testosterone, sex hormone binding globulin, oestradiol, thyroxin, prolactin, Cortisol, follicle stimulating hormone and luteinizing hormone were determined. the girls were divided into age groups and all results were evaluated according to chronological and skeletal age. the number of boys was too small (25) to allow subdivision into age groups.

The girls with idiopathic scoliosis had a significantly higher response to the growth hormone stimulation test than had the controls between the ages of 7 and 12 years whereas no significant difference could be found for the older girls. in girls with a skeletal age between 9 and 12 years a significantly higher mean serum level of testosterone was found (P < 0.05). No significant differences could be demonstrated for the remaining hormones.

Growth hormone and testosterone are the most important growth factors in prepubertal and pubertal children. Thus, the present findings suggest a hormonal basis for the increased stature in children with idiopathic scoliosis which has previously been reported.     

Ultrasound Bone Densitometry of the Os Calcis in Children and Adolescents

The aim of the present investigation was to evaluate reference data and to examine whether there were weight-, height-, age-, and sex-related differences of the quantitative ultrasound bone parameters for healthy children and adolescents. A total of 3299 healthy Caucasian children and teenagers (1623 girls and 1676 boys), age range from 6–18 years (mean age 11.4 ± 3.4 years for boys and mean age 11.5 ± 3.3 years for girls) were examined by quantitative ultrasound densitometry (QUS) using the bone sonometer SAHARA (Hologic Inc., Waltham, MA, USA), a waterless, dry system. The parameters broadband ultrasound attenuation (BUA) [dB/MHz] and speed of sound (SOS) [m/second] were evaluated on the right heel in relation to age, sex, weight, and height. There is no correlation between the ultrasound bone parameter SOS and age, height, and weight. BUA increases with age, height, and weight. Significant differences in SOS and BUA between girls and boys were found to probably be caused by the different onset of growth phases and the onset of puberty. SOS and BUA are influenced by changes of bone mineral density. But BUA is dependent on bone size, too. In conclusion, ultrasound bone densitometry is a useful measuring method showing the physiological bone development in childhood and adolescence. The presented results can be used as reference data. Further studies in children with disorders influencing bone metabolism will show in what way various patterns of osteopenia in childhood can be detected. Received: 20 August 1999 / Accepted: 20 April 2000 / Online publication: 22 September 2000