Laboratory aspects and clinical utility of bone turnover markers

With an aging population, there is a marked increase in prevalence of metabolic bone diseases, especially osteoporosis. Perhaps the most dreaded complication of metabolic bone disease, fractures typically impose a huge burden on the ailing body and are associated with high co-morbidity and mortality. The consequent public health and socioeconomic burden warrant timely diagnosis, treatment and follow-up of these disorders. Knowing the limitations of radiological techniques, biochemical markers of bone turnover measurements come handy since the changes in their levels readily reflect bone physiology. Bone biomarkers typically analyzed in high throughput automated routine laboratories are collagen degradation products, reflecting osteoclast activity, and the collagenous or non-collagenous proteins produced by the osteoblasts. Since bone biomarker levels vary considerably due to quite a few endogenous and exogenous pre-analytical factors, knowledge of these limitations is mandatory prior to clinical utilization since these variabilities complicate test result interpretation. Standardization to harmonize different assay methodologies is desired, and the primary aims of the IFCC/IOF bone marker standards working group are also presented. Current literature data advocate bone markers as best used in monitoring anti-osteoporosis therapy efficacy and compliance, nonetheless, there is abundant data supporting their role in predicting bone loss and fracture risk. Furthermore, they have widespread clinical utility in osteoporosis, renal osteodystrophy, and certain oncological conditions and rheumatic diseases.