What Is Low Bone Density?
Low bone density or decreased bone density means that your bones are not as dense or strong as they should be. Usually this refers to the range where the density or strength of the bones are below normal, but not as low as is seen in osteoporosis. Sometimes this is called osteopenia. In children, the term osteoporosis is used only when the density of the bones is significantly below normal and they have a fracture history. Because of this, the phrase low bone density or decreased bone density can be used in any child whose bone density is below normal in any range, whether or not they have a fracture history.
What Causes Low Bone Density?
There are many factors that lead to low bone density. These are usually the same things that can cause osteoporosis. Some of the factors cannot be changed or prevented, such as a family history of osteoporosis or low bone density. Also, women and persons of white or Asian descent have a higher risk of having low bone density. Age is also a factor. While low bone density can happen at any age, there is a much higher chance of it after age 50 years.
An additional risk factor that can lead to low bone density is having health problems that can affect the bones. These may include:
- Autoimmune disorders such as rheumatoid arthritis and lupus
- Gastrointestinal disorders such as celiac disease and crohn’s disease
- Endocrine disorders such as diabetes, hyperthyroidism and relative energy deficiency syndrome (RED-S)
- Cancer and blood disorders such as leukemia and thalassemia as well as inflammatory lung disease, kidney disease and liver disease
Medications used to treat some disorders can also cause low bone density. Corticosteroid or “steroid” medications are the main medications that can decrease bone density. Some additional medications are some anticonvulsant (seizure) medications, chemotherapy and transplant antirejection medications, and proton pump inhibitors (stomach reflux medications)
Limited weight bearing and low physical activity levels can also lead to low bone density.
What Are Signs & Symptoms of Low Bone Density?
Low bone density and osteoporosis can be silent diseases, where there are not a lot of symptoms. Sometimes a fracture, especially a fragility fracture, might be the first sign.
Some people might have more bone pain with low bone density
How Is Low Bone Density Diagnosed?
Bone density problems are diagnosed with a radiology test called dual-energy x-ray absorptiometry (DXA) scan. This scan does use radiation similar to a traditional x-ray, but at much lower amounts, making it a very safe test. This test is most commonly done in adults, usually in women above 50 years of age since they are at greatest risk for low bone density. It is done in other age groups as well if there are risk factors. The areas to measure and the comparisons used to understand the test results are different in adults and children. Because of this, it is best that your child have this test performed at a facility that frequently evaluates children. Additionally, the test is sensitive, so it is better to have follow up tests done on the same machine over time.
In adults, T-scores are used. These compare the person being evaluated to a general group of persons in their 20’s. In children, Z-scores are used, which compare children to age and gender matched peers. A normal Z-score in a child is between –1.0 and +1.0. Low bone density is diagnosed with a Z-score >/= -2.0 without a history of fracture. Your child’s provider may make a diagnosis of decreased bone density for age and gender with a score less than –1.0 depending on other clinical factors.
How Is Low Bone Density Treated?
If your child has been diagnosed with low bone density, the first thing to figure out is the cause. If the cause is something treatable, like celiac disease or hyperthyroidism, then treating that health problem helps treat the low bone density. If it is from a cause that cannot be fully treated, then the main things are to focus on improved nutrition and physical activity. You will need to make sure your child is getting enough calcium and vitamin D in their diet. Additionally, physical activity can make a positive difference in bone density, especially during the years around puberty. Physical activity should include weight-bearing activities that can include walking, running, soccer, baseball, and tennis. Activity should also include resistance exercises to help with muscle mass. These activities may include biking, rollerblading, swimming, and strength training.
What Are the Long-Term Effects of Low Bone Density?
Some children can have low bone density and may never fracture. If their bone density remains below normal as they grow and mature, they may be at higher risk for fractures and developing osteoporosis now. Additionally, there is a concern that if they spend their childhood and middle adult years with low bone density, they are at high risk for osteoporosis later in life. Sometimes lower bone density can improve during childhood with low risk treatments mentioned above.
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