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What is... osteoporosis?

· 4 min read

Part of the "What is...?" series

Osteoporosis is often known as the "bone thinning" disease that strikes in old age - but is this an accurate description? And is it an inevitable problem in old age or are there steps for you to take right now that will make a difference?

Osteoporosis is not a painful condition, but it does make bone fracture more likely. If a bone fracture occurs in a major bone (like the hip) in an elderly or vulnerable patient then this can lead to complications. The most serious of these is blood clots, which can go on to cause heart attacks, strokes and pulmonary embolism.

What happens in osteoporosis?#

We often think of our bones as big solid lumps of calcium, but actually they are arranged in a matrix of criss-crossing pillars of calcium and protein called trabeculae. These run in lots of different directions, which means that the bone is strong in lots of different directions and able to resist forces through all kinds of movement.

Normal trabeculae in a hip bone

As we've discussed in previous posts, the body is highly adaptable, and is able to change its composition to deal with lots of different environments and challenges. This is true of muscles, for example, which get bigger and stronger with use. It's also true of the nervous system, which is able to re-wire itself to learn a new skill or technique. And it's also true of your bones, because they are able to deposit extra calcium along these trabeculae when the bones are regularly used and loaded. They are also able to do the opposite - to remove calcium from trabeculae that are not being used or loaded.

This is what we see in osteoporosis. When we look on an x-ray, the bones appear almost stripey, because the trabeculae running in one direction have thinned and become less dense, leaving a darker stripe running through the bone.

The classic stripey pattern of osteoporosis in the knee

What can I do to prevent/treat osteoporosis?#

If you remember back to the blog post about osteoarthiritis, we saw there that certain cells called osteoblasts are responsible for building new bone. In osteoporosis, these cells are unable to do their job and there are 5 main causes for this:

  • Inactivity - the osteoblast cells are stimulated by movement and loading, so a sedentary lifestyle will slow down the activity of these cells.
  • Drinking heavily and smoking - both alcohol and cigarette smoke are known to inhibit osteoblasts, and early research on vaping suggests it may also have a similar effect, although this is not conclusive.
  • Having a low BMI - being underweight is a risk factor for developing osteoporosis, partly because it is indicative of a diet low in fat, calcium and Vitamin D - all of which are needed to build healthy bones. But weight is also important because it affects hormone levels (see below).
  • Hormonal changes - osteoporosis is most common in post-menopausal women because osteoblasts slow down when there's a drop in oestrogen, as happens in the menopause. Testosterone is also important for healthy bones in men, so changes in these hormone levels may cause osteoporosis too. Also too much of the thyroid hormones (in both men and women) can slow down osteoblasts.
  • Some medications - for example, long term use of corticosteroids.

The great news is that, if osteoporosis is caught early enough, it is actually possible to reverse it completely. And even if it is caught later on and is already quite advanced, it is possible to slow its progress, stop it progressing completely or partially reverse it. From the list above we can clearly see that a healthy BMI with an active lifestyle, good diet, moderate alcohol intake and no smoking would help prevent osteoporosis.

If you have a family history of osteoporosis, or are have already been diagnosed with it I would recommend the following:

  • Regular weight bearing exercises
  • A strong calcium and Vitamin D supplement
  • Quit smoking and reduce your alcohol intake
  • Get some sunshine! (this helps with Vitamin D, but in the UK you will always need to take a supplement as well)
  • See your GP for advice on medication (there are medications available which help with building bone back up again)

See other posts in the "What is...?" series