HEALTH NEWS

Study Title:

Bone Mineral Density and Inflammatory Bowel Disease

Study Abstract

Low bone mineral density (BMD) has been highlighted as a potential problem in children with inflammatory bowel disease (IBD), which is one of the most common chronic childhood diseases in the westernized world. The mechanisms behind reduced BMD in pediatric IBD are still not completely understood, but several factors that influence bone mineralization have been discussed. These include the chronic inflammation itself, which causes the release of cytokines from the inflamed bowel, treatment with corticosteroids, low body weight, limited physical activity, vitamin D deficiency and genetics. Decreased peak bone mass in young adulthood may predispose for the development of osteoporosis later in life and this in turn may lead to osteoporosis-related fractures.

The aim of this thesis was to investigate BMD, body composition and growth in a population of Swedish children and adolescents with IBD over a two-year period. A second objective was to study the familial resemblance of BMD in pediatric IBD patients. The thesis was designed as a prospective, longitudinal, population-based project with patients from two pediatric centres in Western Sweden (Göteborg and Borås). In order to evaluate BMD and body composition the patients and their parents underwent dual-energy X-ray absorptiometry (DXA) at the time of inclusion in the study. Two years later the DXA measurement was repeated in the IBD patients. Additionally, clinical data, body weight, height, Tanner stage, bone age and blood samples for various hormone analyses were obtained. Age at peak height velocity (PHV) was calculated using special software.

Low bone mass was found to be prevalent in this population of Swedish pediatric patients with IBD both at baseline and at follow-up two years later. Possible risk factors for lower BMD are male gender, low BMI and treatment with azathioprine, which is a likely marker of disease course severity. However, the data indicate that both males and females have the potential to recover BMD into early adulthood. Furthermore, this study demonstrated that, regardless of the presence of a chronic inflammatory condition, the BMD of children and adolescents with IBD is significantly related to that of their parents. Normal vitamin D levels were present in the group of pediatric IBD patients and showed a significant seasonal variation with lower levels during winter time. No significant correlation was found between vitamin D levels and BMD. Elevated levels of intact parathyroid hormone (iPTH) were seen in the patients under 16 years of age despite normal vitamin D levels. Vitamin D and iPTH levels were inversely related. Lean mass deficits were present in the oldest age groups and were most pronounced in males and those with Crohn’s disease. Age at PHV was significantly delayed by around one year in both females and males and this may indicate pubertal delay.

The data from this thesis support the conclusion that pediatric patients with IBD should be evaluated with DXA at some point during the course of their disease, if possible soon after being diagnosed.

From press release:

A thesis from the University of Gothenburg (Sweden) is the first in Scandinavia to study the occurrence of low bone mineral density in children and teenagers with inflammatory bowel disease. Half of the patients in the study showed signs of low bone mineral density. The results emphasise the importance of treating the underlying inflammatory bowel disease more effectively, and of measuring bone mineral density in this group of patients.

Low bone mineral density, or BMD, was evident in around half of the 144 participants with inflammatory bowel disease aged between six and 19 in a major study in western Sweden. Disturbed development of BMD during childhood and adolescence may increase the risk of osteoporosis later in life and thus the likelihood of fractures.

“Possible risk factors for low BMD were more severe disease with increased inflammatory activity in the gut, male gender and low body mass index,” says Susanne Schmidt, researcher at the Institute of Clinical Sciences.

Genetic factors also had a major role to play in the children’s BMD, aside from their chronic gastrointestinal inflammation which itself can affect BMD.

“We investigated the children’s biological parents and measured their BMD,” says Schmidt. “We found a clear correlation between the parents’ and the children’s BMD. Where both parents had a low BMD, a child was six times more likely to have a low BMD too. A similar correlation has previously been described in healthy children and their parents.”

However, the researchers saw that after two years the BMD of the oldest patients was showing signs of recovery, which will be investigated more closely in a follow-up study.

According to Schmidt there have, to date, been neither international nor national guidelines for monitoring BMD in children and teenagers with inflammatory bowel disease. She therefore sees a need to introduce checks on BMD, particularly in those patients with risk factors, such as more active disease, low body mass index or parents with a known low BMD.

“The results of the study also underline the importance of optimising the treatment of these patients to minimise the inflammation which is partly behind the low BMD.”

Inflammatory bowel disease

Inflammatory bowel disease, or IBD, is a group of chronic inflammatory conditions – such as Crohn’s disease and ulcerative colitis – that affect different parts of the gastrointestinal tract. Typical symptoms include loose stools with traces of blood, abdominal pains and poor growth. Almost 1% of the Swedish population has the condition, making it a common complaint, with around a quarter developing it during childhood or the teenage years. IBD has increased significantly over the last few decades among children, both in Sweden and abroad. Around 300 children and teenagers under the age of 18 develop IBD every year in Sweden. It is treated with medicines, surgery and/or nutritional therapy.

Study Information

Susanne Schmidt
Bone mineral density in pediatric inflammatory bowel disease.

2010 August
Department of Pediatrics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.