When, how, and why a bone biopsy should be performed in patients with chronic kidney disease.

In chronic kidney disease the excessive production of parathyroid hormone increases the bone resorption rate and leads to histologic bone signs of secondary hyperparathyroidism. However, in other situations, the initial increase in parathyroid hormone and bone remodeling may be slowed down excessively by a multitude of factors including age, ethnic origin, sex, and treatments such as vitamin D, calcium salts, calcimimetics, steroids, and so forth, leading to low bone turnover or adynamic bone disease. Both high and low bone turnover diseases actually are observed equally in chronic kidney disease patients treated by dialysis, and all types of renal osteodystrophy are associated with an increased risk of skeletal fractures, reduced quality of life, and poor clinical outcomes. Unfortunately, the diagnosis of these bone abnormalities cannot be obtained correctly by current clinical, biochemical, and imaging methods. Therefore, bone biopsy has been, and still remains, the gold standard analysis for assessing the exact type of renal osteodystrophy. It is also the unique way to assess the mechanisms of action, safety, and efficacy of new bone-targeting therapies.