The role of bone biopsy in clinical practice and research.

Survival rates of patients on dialysis have increased with improved dialytic therapy. However, the resultant increased duration of dialysis has led to a rise in renal osteodystrophy (ROD). Because this metabolic bone disease can produce fractures, bone pain, and deformities late in the course of the disease, prevention and early treatment are essential. Types of ROD include predominant hyperparathyroid bone disease, low turnover bone disease (including osteomalacia and adynamic bone disease), and mixed uremic osteodystrophy. Serum PTH levels are commonly used to assess bone turnover in dialyzed patients. However, a recent study in our laboratory found that serum PTH levels between 65 and 450 pg/ml seen in the majority of dialysis patients are not predictive of the underlying bone disease. To date, bone biopsy is the most powerful and informative diagnostic tool to provide important information on precisely the type of renal osteodystrophy affecting patients, the degree of severity of the lesions, and the presence and amount of aluminum deposition in bone. Bone biopsy is not only useful in clinical settings but also in research to assess the effects of new therapies on bone. The methods of in situ hybridization histochemistry (ISHH) and immunohistochemistry (IHC) are providing the means to study local biomolecules that play a role in bone metabolism. As these research tools become more refined, they will become increasingly valuable in the study of bone. Alternatives to the bone biopsy continue to be pursued, but they have not been proven to have the same specificity or sensitivity to effectively determine the potential value of a specific therapeutic regimen.