Chronic kidney disease presents special bone-health challenges

More than 3 million Canadians have chronic kidney disease, or CKD; one of its most common causes is diabetes. As our population ages and obesity rates continue to rise, more people will be diagnosed with these conditions, as well as another you might not expect: osteoporosis.

Osteoporosis is very common. In Canada, it affects one in four women and one in eight men. Women are at particularly high risk of developing the disease because of estrogen’s role in bone health. One problem of the disease is that it is silent until you have a broken bone or fracture. Fractures from osteoporosis can occur with very little injury.

The connection between CKD and osteoporosis is that failing kidneys can lead to a deficiency of Vitamin D, which our bodies need to absorb calcium. Kidneys also help control our parathyroid hormone, which helps regulate the levels of calcium and phosphorus in our bodies. If your parathyroid hormone is elevated, this may accelerate bone loss. Dialysis treatments, which helps remove waste and excess water from the blood — a job usually performed by our kidneys — can also affect bone health. So, patients with CKD are at an increased risk for fractures.

About half of people on dialysis have had an osteoporotic fracture, compared with one fifth of otherwise healthy people. A younger person with CKD who has had a hip fracture is about 30 per cent more likely to die within a year of their injury than if they were otherwise healthy.

When I first started working in the osteoporosis clinic, I saw a lot of patients who had both CKD and fractures. But I was uncertain how to provide the best care for these patients. For example, the role of the bone density test, which is standard for diagnosing osteoporosis in otherwise healthy people, had not been shown to be useful in CKD. There were no data in medical journals on appropriate treatments for osteoporosis or even risk factors for fracture in CKD. But that’s changing.

As a clinical researcher in osteoporosis, I’m looking at ways to assess fracture risk in people with CKD and how to identify their risk factors for fractures. My lab recently found that bone density testing can predict risk in CKD.

I am also studying potential treatments for osteoporosis in people with CKD. There are few treatments for people balancing renal failure and osteoporosis. The most commonly prescribed treatments for osteoporosis, called bisphosphonates, aren’t recommended for people with CKD because they’re excreted by the kidney and haven’t been well studied in those with impaired renal function.

Most people know getting enough calcium is a great way to keep their bones strong. Doctors recommend 1200 milligrams each day through diet and supplement. A Vitamin D supplement is also helpful because many Canadians are deficient in Vitamin D. A daily supplement of 600 to 1000 IU is also a good idea because most of the foods we eat aren’t vitamin D-fortified.

As we age, we lose bone density and muscle mass, which can make us frail. This puts us at an increased risk for falling, which can result in a fracture. Our reflexes can also decline, making us more likely to fall to the side and break a hip rather than breaking the fall with our wrists. So, it’s important to remain physically active, and to include weight bearing activity in your fitness plan. It can have modest effects on bone density, and help you maintain muscle mass and coordination leading to a reduced risk of falling and ultimately, fractures.

Having a bone density test is key way to assess your fracture risk for both men and women. This test is recommended at least once for men and women aged 65 and over. If you have other risk factors — like having gone through menopause, taking prescription steroid drugs like prednisone for other conditions, family history, smoking, excess alcohol consumption or previous fractures — you may need to have the test done earlier.