Bone metabolism and fracture risk during and after critical illness

There is growing evidence that bone health is impacted during and after critical illness in multiple ways. In this review, we provide a practical update on postcritical care bone loss with an insight on identification of persons at risk, prevention and treatment strategies.

Critical illness is associated with an increase in bone turnover and with an uncoupling between bone resorption and bone formation. This results in loss of bone mass, as highlighted by changes in bone marker serum levels and in bone mineral density. Data suggest that ICU survivors are at an increased risk of bone fractures, but this is not completely quantifiable. A key driving factor for ICU-related bone loss, beside inflammation, undernutrition and vitamin D deficiency, is immobilization. Bone health and muscle health are closely related, through myokines and osteokines. Even if not completely proven in the context of critical care, it is likely that preserving muscle mass and strength helps reducing bone loss.

A history of critical illness should be considered as a strong risk factor for osteopenia and osteoporosis. ICU-related bone loss should be part of the postintensive care syndrome, and should be targeted by prevention and treatment strategies. Optimized and individualized protein and micronutrient provision (with specific attention to calcium, vitamin D and selenium), associated with physiotherapy and muscle training, should be implemented early after ICU admission and continued after ICU discharge. Antiresorptive agents such as biphosphonates should be considered on an individualized basis.