Long-Term Development of Bone Geometry and Muscle in Pediatric Inflammatory Bowel Disease

Division of Pediatric Gastroenterology and Hepatology, Dr von Haunersches Kinderspital, Ludwig-Maximilians-University of Munich, Munich, Germany.
The American Journal of Gastroenterology (Impact Factor: 10.76). 01/2011; 106(5):988-98. DOI: 10.1038/ajg.2010.495
Source: PubMed


The muscle-bone unit is crucial for normal bone development. As muscle mass is frequently reduced in pediatric patients with inflammatory bowel disease (pIBD), we investigated the impact of muscles on the bone development over time.
Bone and muscle parameters were measured repeatedly in 102 pIBD patients (67 boys; 82 Crohn's disease; 30 newly diagnosed) by peripheral quantitative computed tomography (pQCT) at the forearm. The first and last measurements were included in the evaluation. Results were expressed as sex- and age-specific and partly height-corrected Z-scores for a healthy reference population.
At baseline, patients showed reduced Z-scores for height (median -0.7; range -3.7 to 1.6), trabecular bone mineral density (TrbBMD; -0.6; 3.0-2.8), and for height-corrected cortical cross-sectional area (CSA(height); -0.4; -3.0 to 2.2), cortical thickness (CrtTh(height); -0.7; -3.0 to 1.2), and MuscleCSA(height) (-1.0; -4.9 to 2.0; all P<0.01). Cortical bone mineral density (CrtBMD) and height-corrected TotalCSA(height) Z-scores were elevated (0.57; -4.55 to 2.8, both P<0.01). Over time, TotalCSA(height) (+0.36; -1.5 to 4.5) further increased, CorticalCSA(height) (+0.21; -2.1 to 3.0) and MuscleCSA(height) (+0.64; -2.0 to 3.9, all P<0.01) improved, whereas CrtBMD decreased toward normalization (-0.36; -5.1 to 3.6, P<0.05). The change in MuscleCSA(height) significantly correlated with the changes in TrbBMD (r=0.42), TotalCSA(height) (r=0.35), CorticalCSA(height) (r=0.38), and CrtTh(height) (r=0.24; all P<0.02). The relations became even stronger after adjustment for several confounders.
Bone metabolism and geometry are altered in pIBD patients expressed by low trabecular mineral density, low cortical thickness, and high cortical mineral density. The increased height-corrected cortical CSA might reflect a compensatory effect. In our cohort, treatment increased height-corrected muscle CSA and its changes were closely associated with bone parameters. Therefore, physical activity to enhance muscle mass and bone health should be promoted in pIBD patients.

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    ABSTRACT: Physical activity is important for muscle and bone strength in the growing child and may be impaired in paediatric patients with inflammatory bowel disease (IBD) even during quiescent disease. The SenseWearPro(2) armband allows to measure physical activity under everyday life conditions. Thirty-nine IBD patients (27 Crohn's disease, 12 ulcerative colitis, 24 boys) in remission (n=26) or with only mild disease activity (n=13) were compared to 39 healthy age and sex-matched controls. Body weight, height, body mass index (BMI), lean body mass as phase angle α (determined by bioelectrical impedance analysis), and dynamometric grip force were expressed as age- and sex-related Z-scores. SenseWearPro(2) armbands were applied for three consecutive days to record number of steps, duration of physical activity and sleeping time. Quality of life was assessed with the German KINDL and IMPACT III questionnaires, energy intake with prospective food protocols. Differences between patients and pair-matched controls were analysed by paired t-test. Patients showed lower Z-scores for phase angle α (difference -0.72; 95% CI [-1.10; -0.34]) and lower grip strength (-1.02 [-1.58; -0.47]) than controls. They tended towards lesser number of steps per day (-1339 [-2760; 83]) and shorter duration of physical activity (-0.44 h [-0.94; 0.06]), particularly in females and patients with mild disease. Quality of life and energy intake did not differ between patients and controls. In spite of quiescent disease lean body mass and physical activity were reduced. Interventions to encourage physical activity may be beneficial in this lifelong disease.
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    ABSTRACT: Objectives: Low bone mineral density (BMD) is recognized as a potential problem in children with inflammatory bowel disease (IBD). We aimed to describe the longitudinal development of BMD in a population of Swedish pediatric patients with IBD. Methods: A total of 144 patients with IBD (93 males; 83 with ulcerative colitis [UC], 45 with Crohn disease [CD]) were examined with dual-energy x-ray absorptiometry at baseline. At follow-up 2 years later, 126 of the initial 144 patients were reexamined. BMD values are expressed as z scores. Results: Children with UC and CD had significantly lower mean BMD z scores for the lumbar spine (LS) at baseline and after 2 years. The reduction in BMD was equally pronounced in patients with UC and CD, and neither group improved their z score during the follow-up period. Furthermore, significantly lower mean BMD z scores for the LS were found at baseline in boys (-1.1 SD, ±2.7 SD, P < 0.001), but not in girls (-0.0 SD, ±3.0 SD). This finding remained unchanged at follow-up. Subanalyses of the different age groups at baseline showed the lowest BMD values in the group of patients ages 17 to 19 years in boys (mean z score for the LS 1.59 SD, ±3.1 SD) and in girls (mean z score for the LS -3.40 SD, ±3.1 SD); however, at follow-up, these patients had improved their BMD significantly (mean change z score for the LS 1.00 SD, 95% CI 0.40-1.60; 1.90 SD, 95% CI 0.60-3.20). Conclusions: In this longitudinal study, the entire group of pediatric patients with IBD showed permanent decreases in their BMD z scores for the LS; however, our data indicate that afflicted children have the potential to improve their BMD by the time they reach early adulthood.
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    No preview · Article · Jun 2012 · Calcified Tissue International
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