The prevalence of osteopenia in children with inflammatory bowel disease (IBD) is unknown. The eVect of nutritional state, disease activity, and steroid therapy on bone mineral content (BMC) of whole body, lumbar spine, and left femoral neck measured by dual energy x ray absorptiometry in 32 children with IBD was assessed by comparison with 58 healthy local school children. Using the control data, a predicted BMC was calculated taking into account bone area, age, height, weight, and pubertal stage. The measured BMC in children with IBD was expressed as a percentage of this predicted value (% BMC). Mean (SD) % BMC was significantly reduced for the whole body and left femoral neck in the children with IBD (97.0 (4.5)% and 93.1 (12.0)% respectively, p<0.05). Of the children with IBD, 41% had a % BMC less than 1 SD below the mean for the whole body and 47% at the femoral neck. Reduction in % BMC was associated with steroid usage but not with the magnitude of steroid dose, disease activity, or biochemical markers of bone metabolism. In conclusion, osteopenia is relatively common in childhood IBD and may be partly related to the previous use of steroids. (Arch Dis Child 1997;76:325-329)

Dual-energy X-ray absorptiometry (DEXA) is a rapid and precise technique for the assessment of bone mineralization in children. Interpretation of the results in growing children is complex as results are influenced by age, body size (height and weight) and puberty. Conventionally, bone mineral data derived from DEXA have been presented as an areal density [BMD; bone mineral content (BMC, g)/projected bone area (BA, cm2)], yet this fails to account for changes in BMC that result from changes in age, body size or pubertal development. Measurement of BMC and BA of the whole body, lumbar spine and left hip were made in 58 healthy boys and girls using DEXA. The relationship between BMC and BA was curvilinear, with the best fit being that of a power model (BMD = BMC/BAlambda, where lambda is the exponent to which BA is raised in order to remove its influence on BMC). The value of lambda changed when measures of body size and puberty were taken into account (e.g. for lumbar spine from 1.66 to 1.49). Predictive formulae for BMC were produced using regression analysis and based on the variables of age, body size and pubertal development. This provides a method for interpreting the measured BMC which is independent of such variables and a constant reference range for children aged 6-18 y.

The overall incidence (95% confidence intervals) for IBD in Wales was 2.6 (1.87-3.48) cases per 100,000 per year. The incidence for Crohn's disease was 1.36 (0.86-2.04) cases per 100,000 per year, for UC 0.75 (0.39-1.28) cases per 100,000 per year and for indeterminate colitis 0.48 (0.2-0.92) cases per 100,000 per year.

Recently published standards for body mass index (BMI) based on population studies of height and weight in healthy British children allow an easy but indirect assessment of adiposity in healthy children. However, assessment of adiposity based on standards derived from reference populations may not be appropriate for use in subjects with disease states associated with abnormalities of growth and body composition. This hypothesis was tested by comparison between BMI standard deviation scores (SDS) and more direct measures of body fat derived from dual-energy X-ray absorptiometry (DEXA) and skinfold thickness in groups of children, receiving growth hormone, with inflammatory bowel disease, previously treated for malignancy, and healthy controls. Excess adiposity was defined as a body fat greater than the 85th percentile and was compared to a BMI SDS of +1.0. Overall the sensitivity and specificity for a BMI SDS of +1.0 to correctly identify individuals as having excess adiposity was 66% and 94%, respectively, when body fat was measured by DEXA, and 50% and 100% when estimated from skinfold measurements, respectively. There were no significant differences in these statistics whether applied to the individual disease groups or to healthy controls. These findings suggest that BMI under-predicts the prevalence of excess adiposity in children with disease states but surprisingly to no greater degree than that seen in healthy subjects.

Aims-To evaluate the eVects of discontinuing growth hormone (GH) treatment on energy expenditure and body composition, which might help predict those most likely to benefit from early reintroduction of GH treatment in young adult life. Methods-Body composition was calculated from skinfold thicknesses and dual energy x ray absorptometry (DXA). Resting metabolic rate (RMR) and whole body bone mineral content (BMC) were also measured. Measurements were made before stopping treatment, at discontinuation of GH treatment, and two weeks, six months, and one year later in 11 adolescents with growth hormone deficiency (GHD) and five adolescents without GHD who were treated with GH. Measurements were compared with 10 healthy controls, in whom measurements were repeated one year later. Results-During the nine months before discontinuation of GH there were no changes in body composition, RMR, or BMC of patients with GHD, nor diVerences when compared with controls. RMR was reduced by 11.3 kJ/kg fat free mass two weeks after stopping GH in GHD patients and remained suppressed thereafter compared with controls. Percentage body fat increased by 4.3%/year in patients with GHD after discontinuing GH, whereas no changes were noted in control or non-GHD patients at one year. The patients experiencing the greatest reductions in RMR/kg fat free mass at six months showed the largest increases in body fat at one year. No change in BMC was noted in patients one year after stopping treatment. Conclusion-Important metabolic changes occur early after discontinuing GH treatment. In patients whose growth is complete, these changes might be used to predict those most likely to benefit from continuation of GH treatment into adult life. (Arch Dis Child 1999;80:517-523)