SARCOIDOSIS AND THE BONE
What are Bones?
The human skeleton has 206 bones. They give the body strength and serve as a framework for the muscles. Although the bone is hard and has a solid form, it is a very active living tissue that responds to external stimuli. That is shown by its ability to recover after a fracture. Also new bone is constantly created under normal and degraded old tissue. So the bone is constantly renewed throughout life.
This balance between renewal and degradation varies with age. Growing children will create more bone than is destroyed. In old age this is exactly the opposite - more is broken down than created. Between the twentieth and thirtieth year the bones reach their maximum mass.
In addition to this balance between renewal and degradation, the quality of the bone is important. The bone structure should be firm. Heredity, diet, exercise and sunlight all contribute to this.
What is Osteoporosis?
Bone loss (osteoporosis) is a disease where bone mass across the whole skeleton has decreased and the bone structure has changed. This makes the bone weaker and it breaks more easily. Osteoporosis is a natural process that increases with age. In women, there is an increased rate after the menopause.
Osteoporosis and Sarcoidosis
Several diseases can lead to osteoporosis and sarcoidosis is one of them. This may occur as a direct symptom of the disease itself or as a result of the long-term use of high dose corticosteroids.
Approximately half of sarcoidosis patients will receive corticosteroids (prednisone or prednisolone). These are required to suppress the inflammation of the sarcoidosis. Patients usually have to use a long-term, high doses of this medication. This can then cause various side effects, including osteoporosis.
Which Bones are Affected?
In principle, all bones are affected. However most of the bones of the lower back (lumbar spine), and the wrist (distal radius) respond particularly quickly to the use of high doses of corticosteroids, significantly increasing the risk of fracture. This happens especially in the first few months of medication.
Techniques to Understand your Condition
DXA (Dual Energy X-ray Absorptiometry) scan: This technique measures bone mineral density using X-rays. The measurement demonstrates bone loss (osteoporosis). Because osteoporosis in itself gives no symptoms and a fracture is often the first appointment, the doctor can be alerted to the possibility of the presence of the condition.
Quantitative Computed Tomography (QCT) and Ultrasonography: These techniques can be used to assess bone density but they are not yet clinically widespread. QCT is very detailed but costly and ultrasonography is inexpensive but has not yet been fully validated.
X-ray: X-rays map the spine and surrounding vertebrae to examine existing vertebral faults which may be a result of reduced bone strength.
Calcium content: Normal calcium levels can be disrupted by sarcoidosis. If necessary, the doctor will monitor the level of calcium in the blood and urine.
Vitamin D assessment: Vitamin D levels, an important factor in bone health, may be altered by sarcoidosis. Therefore, the doctor may test your blood for vitamin D.
Your doctor may prescribe a dose of > 7.5 mg prednisone per day, for a long period of time, to medicate the effects of sarcoidosis. Bisphosphonate drugs may also be prescribed as a precaution as these reduce corticosteroid-induced bone loss. In addition, patients may sometimes be prescribed calcium and/or vitamin D supplements.
Hormone replacement therapy may be recommended as a treatment for osteoporosis for post-menopausal women.
Maintain healthy and strong bones by:
being physically active (if you can, exercise for 30 minutes’ per day, 5 days a week);
consuming enough calcium: depending on your current level of calcium in the blood and urine. Calcium is high in dairy products (milk and cheese) and is also in fruit juice and vegetables;
getting enough vitamin D. This comes from sunlight and helps in bone development.