2.4 Bone health in Parkinson’s

This section has so far addressed the nature of bone health in the general population. What are the specific issues of bone health in Parkinson’s?

Section 1 presented an overview of the risk of falls and consequent fractures in Parkinson’s, particularly hip fracture. A recent systematic review showed that people with Parkinson’s are over twice as likely to have osteoporosis compared to controls (Torsney et al, 2014). Despite this, women with Parkinson’s perceive themselves as ‘as likely or less likely’ to fracture a bone compared with their peers (Gregson et al, 2014). All clinicians have a responsibility to ensure that bone health is addressed in Parkinson’s clinics.

Several factors contribute to reduced BMD and bone strength in Parkinson’s (van den Bos et al, 2013). These include reduction in muscle strength, mobility, load bearing exercise and sunlight exposure. Less vitamin D synthesis occurs as a result. There is also a tendency towards low body mass index and even malnutrition. This is because medications can impact on nutrition, and levodopa has effects on homocysteine handling and collagen cross-linking in bone. Vitamin D is very important to bone health, as it promotes absorption of calcium from the diet and suppression of PTH, tipping the balance in favour of bone formation. 80% of vitamin D comes from the exposure of sunlight on the skin – while about 20% is taken in the diet. Deficiency is common in the general population, especially where sunlight exposure is low. Low vitamin D is associated with poor bone health, as well as several other conditions. People with Parkinson’s have been shown to have low levels of vitamin D compared to the general population (Knekt et al, 2010) and it is good practice to offer vitamin D supplementation to all people with Parkinson’s. Testing vitamin D levels is not required. However, doing this may help encourage some patients to adhere to their prescribed course of vitamin D.