Osteoporosis is a condition that causes the bones to become weak and fragile and more likely to fracture. Bones have a hard outer shell with a mesh of collagen, minerals, blood vessels and bone marrow inside, which has a honeycomb appearance. Healthy bones are very dense, with only small spaces inside the bone. Bones affected by osteoporosis have larger spaces and hence lower bone mass, making them weaker and more likely to break.
Bone Mass Loss: In the general population, bone mass loss occurs very gradually after the age of 35. This bone loss becomes more rapid in women for the first few years following the menopause and can lead to osteoporosis.
Measuring bone density: Osteoporosis is diagnosed with a bone density scan, called a dual energy X-ray absorptiometry (DXA) scan. DXA scans are quick and painless.
Body Mass Index: Check out your own BMI on the NHS website. The research talks about a BMI of 24kg/m2 or less. It is important to note that this actually falls within the normal range for adults, which is 20-25kg/m2, so it could affect any of us.
Recent research has confirmed what we already suspected: PSCers are more likely to suffer from osteoporosis than non-PSCers (Angulo et al. 2011). The team conducted a long-term study to determine the prevalence and rate of progression of bone disease in PSCers and to identify factors that could be used to predict bone disease and progression.
The bone density of 237 PSCers was measured yearly for nearly a decade. Osteoporosis was 23.8 times higher in PSCers than expected compared to non-PSCers. They found that being aged 54 or more, having a body mass index of 24kg/m2 or less, and having inflammatory bowel disease (IBD) for over 19 years was related to the presence of osteoporosis. In fact, 75% of patients with all three of these risk factors had osteoporosis compared to only 3.1% of patients without all three.
Interestingly, this study also found that patients with PSC lost bone mass at an average rate of 1% per year, which was significantly higher than that of the non-PSCers. Even when such factors as hormone replacement therapy, use of corticosteroids and vitamin D/calcium supplementation were included, the bone loss seemed to be greatly influenced by the length of time the patients had had IBD. The researchers conclude that the longer duration of IBD may be the most important factor affecting bone mass in patients with PSC who also have IBD.
However, Francisco Sylvester, in his editorial of the journal which published the study, questioned whether the lower BMI readings were associated with reduced fat or reduced skeletal muscle mass. This is an important distinction because decreased skeletal muscle mass, strength and power can negatively affect bone. Sylvester goes on to suggest that the effect of age on bone mass shown in the study may have been confounded by the number of post-menopausal women participants in the sample. Future research may be able to control for this.
The data in this study can be used to suggest guidelines for BMD testing in patients with PSC. The authors suggest the using an initial BMD reading when PSC is diagnosed, and these results (along with the risk factors of older age, lower BMI and duration of IBD) used to determine the frequency of follow-up testing to allow for early identification and management of bone disease:
- All patients - at time of diagnosis of PSC
- PSCers with normal bone mass and short duration of IBD every 24-36 months
- PSCers with bone mass in range of osteopenia (especially those with long-lasting IBD) - every 6-12 months
There is currently no data on the prevention and treatment of bone disease in PSCers. However, the researchers support the following general recommendations:
- Increased physical exercise
- Discontinued alcohol intake and smoking
- Diet high in calcium and vitamin D (or supplementation if deficient).
The researchers suggest that patients with established osteoporosis and those who have had a fragility fracture (a fracture which occurs as a result of normal everyday activities) should be treated for bone disease, especially patients with all three risk factors (older age, lower BMI and longer duration of IBD) and those on the waiting list for liver transplantation. “A significant increment in the risk of fragility fractures is expected in the post transplantation period” (p. 186).
Therefore PSCers should be aware that our bone mass is decreasing. If we have a lower BMI than 24kg/m2, are over 54 and have had IBD for over 19 years, then we should be vigilant about osteoporosis and being monitored.
Warning – please do not make any changes to your diet or exercise regime without first consulting your GP.
References Angulo P, Grandison GA, Fong DG, Keach JC, Lindor KD, Bjornsson E & Koch A., 2011. Bone Disease in Patients With Primary Sclerosing Cholangitis. Gastroenterology, 140, pp.80-188 [doi:10.1053/j.gastro.2010.10.014] (Special thanks to Professor Keith Lindor for providing us with the full text of the research paper.) National Osteoporosis Society, 2011. About Osteoporosis. [online] Accessed 20 February 2011] NHS Choices, 2011. NHS Health A-Z. Osteoporosis. [online] [Accessed 20 February 2011] Sylvester F, 2011. Editorial. The Impact of Gastrointestinal and Liver Diseases on Bone: It Ain’t Like Menopause! Gastroenterology, 140, pp. 22-25