Low-grade systemic inflammation and suboptimal bone mineral density throughout adolescence: a prospective study in girls.

OBJECTIVE

We aimed at quantifying the associations between high-sensitivity C-reactive protein (hs-CRP) and forearm bone mineral density (BMD) throughout adolescence in overweight and normal-weight girls.

DESIGN

Prospective cohort study.

PATIENTS: 346 girls born in 1990 and attending schools in Porto, Portugal.

MEASUREMENTS: Adolescents were evaluated at 13 and 17 years of age using a standard protocol. Forearm BMD was measured by dual-energy X-ray absorptiometry. Anthropometric assessment included weight, height, body fat percentage and waist circumference. Girls were categorized according to age- and sex-specific body mass index (BMI) percentiles as normal weight in both evaluations or overweight in at least one assessment. Pubertal development was estimated using menarche age. Serum hs-CRP was determined using particle-enhanced immunonephelometry. Hs-CRP was log-transformed, and associations were quantified using linear regression coefficients and 95% confidence intervals (95%CI).

RESULTS

An inverse association between hs-CRP and BMD was observed from 13 years of age in overweight girls [-11·26 mg/cm(2) (-21·99, -0·52)]. Among normal-weight adolescents, 13-year-old hs-CRP was negatively associated with prospective BMD variation between 13 and 17 years of age [-1·90 mg/cm(2) year (-3·35, -0·45)]. Overweight girls who maintained higher levels of hs-CRP throughout adolescence had lower 17-year-old BMD (adjusted mean 0·441 vs 0·483 g/cm(2) in those who remained with lower levels of hs-CRP). At 17 years of age, significant inverse associations were found between hs-CRP and BMD among normal-weight and overweight girls.

CONCLUSIONS

Obesity-related early systemic inflammation might be involved in suboptimal bone accrual, particularly in overweight girls.