How Bone Disease is Related to Kidney Function
Bone disease resulting from kidney dysfunction (renal osteodystrophy) affects 90 percent of dialysis patients but starts early in chronic kidney disease (CKD) stage 3-4. If left untreated, the bones gradually become thin and weak, leading to bone and joint pain and increased risk of bone fractures.
Hormones and minerals
In healthy adults, bone tissue is continually being remodeled and rebuilt. The kidneys are the seat of calcium, phosphorus and vitamin D control. Your kidney converts simple vitamin D into its active form. Kidneys constantly talk with the parathyroid gland in the neck. All of these functions are progressively affected as kidney disease progresses.
To diagnose renal osteodystrophy, your doctor may take a sample of your blood to measure levels of calcium, phosphorus, vitamin D and parathyroid hormone (PTH). The doctor may seldom perform a bone biopsy to see how dense your bones are. Determining the cause of renal osteodystrophy helps the doctor decide on a course of treatment.
Controlling calcium, vitamin D, phosphorus and PTH levels with change in diet and/or medications is the first step.
Reducing dietary intake of phosphorus is one of the most important steps in preventing bone disease. Almost all foods contain phosphorus, but it’s especially high in milk, cheese, dried beans, peas, nuts, peanut butter, cocoa, dark sodas, and beer, to name a few. Added food preservatives are often very high in phosphorus. Our overall phosphorus consumption is much higher than it used to be. (To learn more about phosphorus and the kidney diet, click here).
Sometimes, kidney patients need activated vitamin D (called calcitriol) instead of simply vitamin D to achieve adequate bone density.
Exercise has been found to increase bone strength in some patients.
Improper control of the above can lead to hyperparathyroidism (over-functioning of the parathyroid gland) which also needs to be controlled with medications.
Regular follow-ups with your nephrologist with timely blood tests can help keep a lot off the above conditions at bay.