Clinical risk factors associated with bone biopsy findings in CKD-associated osteoporosis: insights from the Brazilian Registry of Bone Biopsy (REBRABO)

Abstract

Chronic kidney disease–associated osteoporosis (CKD-OP) is a highly prevalent—yet frequently underrecognized—condition in patients with advanced CKD. The assessment of bone turnover, mineralization, and volume remains challenging in clinical practice, often requiring bone histomorphometric analysis. Using data from the Brazilian Registry of Bone Biopsies (REBRABO), we identified clinical characteristics associated with these histomorphometric parameters. These findings may help clinicians better characterize the underlying bone phenotype and support a more individualized approach to the diagnosis and management of CKD-associated osteoporosis. Chronic kidney disease–associated osteoporosis (CKD-OP) is characterized by impaired bone quality, and management of bone fragility in CKD partially relies on evaluating bone turnover (T), mineralization (M), and volume (V), through bone biopsy. However, bone biopsy data from large population-based cohorts are limited, making it challenging to identify clinical parameters that are associated with TMV patterns. This cross-sectional study is based on data from the Brazilian Registry of Bone Biopsy (REBRABO) and includes 374 iliac crest bone biopsies from adult patients with CKD5D (median age 51 y), collected between August/15 and December/21. Each biopsy was classified according to bone turnover (low/normal vs. high), mineralization (normal vs. abnormal), and trabecular volume (normal vs. low). Demographic and laboratory parameters were also analyzed. No significant differences in TMV classification were observed based on ethnicity, sex, or diabetes status. Higher turnover was independently associated with younger age, hemodialysis modality, elevated parathyroid hormone (PTH), and alkaline phosphatase (ALP) levels, in a model adjusted for dialysis vintage, prior parathyroidectomy (PTX), and phosphate. Abnormal mineralization was independently associated with age, prior PTX, and lower serum calcium and phosphate, after adjustment for body mass index (BMI), PTH, and ALP. Low trabecular volume was independently associated with older age and lower BMI, in a model adjusted for PTH and history of fractures, and cannot be reliably inferred from biochemical markers. Notably, most patients with adynamic bone also presented with low trabecular volume. Our findings suggest that younger patients undergoing hemodialysis with elevated PTH and ALP levels may benefit from a more intensive approach to the management of hyperparathyroidism. In contrast, older and more frail patients with relatively low PTH levels may be more likely to exhibit low bone volume and turnover and could potentially benefit from therapies aimed at stimulating bone formation, such as anabolic agents.