The role of bone biopsy in clinical practice and research

Survival rates of patients on dialysis have increased with improved dialyti c 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 gain, and deformities late in the course of the disease, prevention and early treatment are essential. Types of ROD includ e predominant hyperparathyroid bone disease, low turnover bone disease (inc luding osteomalacia and adynamic bone disease), and mixed uremic osteodystr ophy. Serum PTH levels are commonly used to assess bone turnover in dialyze d 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 a re not predictive of the underlying bone disease. To date, bone biopsy is t he most powerful and informative diagnostic tool to provide important infor mation on precisely the type of renal osteodystrophy affecting patients, th e degree of severity of the lesions, and the presence and amount of aluminu m deposition in bone. Bone biopsy is not only useful in clinical settings b ut also in research to assess the effects of new therapies on bone. The met hods of in situ hybridization histochemistry (ISHH) and immunohistochemistr y (IHC) are providing the means to study local biomolecules that play a rol e in bone metabolism. As these research tools become more rt fined, they wi ll become increasingly valuable in the study of bone. Alternatives to the b one biopsy continue to be pursued, but they have not been proven to have th e same specificity or sensitivity to effectively determine the potential va lue of a specific therapeutic regimen.