Inhaled corticosteroids and bone mineral density at school age: a follow-up study after early childhood wheezing.

OBJECTIVE: The aim of the study was to evaluate the association between previous use of ICS and bone mineral density (BMD) at school age in a cohort followed after early childhood wheezing. METHODS: As part of a prospective follow-up study after hospitalization for wheezing at <24 months of age, BMD was measured in 89 children at 12.3 (median) years of age. Data on ICS use were collected by interviewing the parents, and this was supplemented with data from patient records. Cumulative doses and the duration of ICS use were calculated. Areal BMD (BMDareal , g/cm(2) ) was measured by dual energy X-ray absorptiometry (DXA), and apparent volumetric BMD (aBMDvol , g/cm(3) ) was calculated, for the lumbar spine and femoral neck. Weight, height and pubertal stage were recorded. FINDINGS: Age, sex, and pubertal stage were significantly associated with BMDareal and aBMDvol of the lumbar spine and BMDareal of the femoral neck. The regular use of ICS for >6 months at age <6 years was associated with a lower BMD of the lumbar spine. A lower BMDareal and aBMDvol of the femoral neck were associated with higher cumulative doses of ICS at age 0-12.3 (median) years. The results were robust to adjustment for age, sex, pubertal stage, height, weight, and use of systemic steroids. CONCLUSION: ICS use during childhood may be related to a decrease in BMD at late school age. It is important to use the lowest possible ICS dose that maintains adequate asthma control.

Associations of genetic lactase non-persistence and sex with bone loss in young adulthood.

Some studies have reported that after attainment of peak bone mass (PBM), slow bone loss may occur in both men and women; however, findings are inconsistent. Genetic factors play a significant role in bone loss, but the available evidence is conflicting. Genetic lactase non-persistence (lactase C/C(-13910) genotype) is suggested to increase risk for inadequate calcium intake predisposing to poorer bone health. We investigated whether this genotype is associated with PBM and bone loss in young Finnish adults. Subjects belong to the Cardiovascular Risk in Young Finns Study that is an ongoing multi-centre follow-up of atherosclerosis risk factors. From the original cohort, randomly selected subjects aged 20-29 participated in baseline bone mineral density (BMD) measurements (n=358), and in follow-up measurements 12 years later (n=157). Bone mineral content (BMC) and BMD at lumbar spine (LS) and femoral neck (FN) were measured at baseline and follow-up with dual energy X-ray absorptiometry (DXA). Lactase C/T(-13910) polymorphism was determined by PCR and allele-specific fluorogenic probes. Information on lifestyle was elicited with questionnaires. During the follow-up, bone loss at both bone sites was greater in males (LS BMD: -1.1%, FN BMD: -5.2%) than in females (LS BMD: +2.1%, FN BMD: -0.7%) (both bone sites p=0.001). Younger age predicted greater loss of FN BMC and BMD in females (p=0.013 and p=0.001, respectively). Increased calcium intake predicted FN BMD gain in both sexes (in females B=0.007 g/cm(2)/mg, p=0.002; in males B=0.006, p=0.045), and increased physical activity LS BMD gain in females (B=0.091 g/cm(2)/physical activity point, p=0.023). PBM did not differ between the lactase genotypes, but males with the CC(-13910) genotype seemed to be prone to greater bone loss during the follow-up (LS BMD: C/C vs. T/T p=0.081). In conclusion, bone loss in young adulthood was more common in males than in females and seemed to occur mainly at the femoral neck. Young males with the lactase CC(-13910) genotype may be more susceptible to bone loss; however, calcium intake predicts changes in bone mass more than the lactase genotype.