Renal osteodystrophy in developing countries

Fibroblast growth factor-23 may serve as a novel biomarker for renal osteodystrophy progression

The purpose of the present study was to determine whether fibroblast growth factor (FGF)‑23 could serve as a novel biomarker for renal osteodystrophy (ROD) progression. A rat model of ROD was induced by left nephrectomy plus intravenous injection of Adriamycin. Serum FGF‑23 was determined using an enzyme‑linked immunosorbent assay. Serum level and bone expression of FGF‑23 were both significantly elevated in the ROD group at 24 h post‑surgery. Serum FGF‑23 was negatively correlated with calcium, phosphate, 25‑hydroxyvitamin D, conventional bone biomarkers and bone collagen X. More importantly, serum FGF‑23 was significantly associated with abnormalities in bone formation rate, osteoblasts, osteoclasts, trabecular volume thickness and osteoid volume. Therefore, FGF‑23 may serve as a novel biomarker for ROD.

Experimental renal failure and iron overload: a histomorphometric study in rat tibia

Renal failure (RF) is a serious disease of relatively high incidence, known to cause bone alterations. RF patients frequently suffer anemia, which is usually treated with iron. Given that iron overload inhibits bone formation, the aim of the present study was to evaluate the effect of iron on the subchondral bone of rat tibiae, using a model of renal failure. Male Wistar rats were subjected to experimental nephrectomy in order to induce renal failure and to iron overload by daily intraperitoneal injections of 88 mg/kg body weight of iron-dextran for 16 days. Tetracyclines were injected intraperitoneally to evaluate dynamic parameters of bone. Undecalcified histological sections of the tibiae were obtained. Serum urea, creatinine, and paratohormone (PTH) levels were evaluated 30 days after the onset of the experiment. Static and dynamic histomorphometric measurements were performed. Iron overload modified the response of the animals with renal failure: a reduction in bone forming activity compatible with adynamic bone disease and a decrease in peritrabecular fibrosis were observed. Our results suggest that iron is yet one more factor involved in the imbalance in bone metabolism typically found in renal failure patients treated with iron, rendering diagnosis and treatment of bone disease in these patients more complex.

The renal osteodystrophy pattern in Brazil and Uruguay: an overview

BACKGROUND

The prevalence of the types of renal osteodystrophy (ROD) has changed in the last two decades. This study evaluates the prevalence and determining factors of the types of ROD in two countries in South America.

METHODS

Symptomatic patients who underwent bone biopsies for diagnostic purposes (1985 through 2001) were included in the study. In Brazil, a total of 2340 patients were reviewed, 93.1% on hemodialysis (HD), and 6.9% on continuous ambulatory peritoneal dialysis (CAPD). In Uruguay, 167 patients on hemodialysis were included. Uncalcified bone samples were analyzed in order to diagnose the different types of ROD.

RESULTS

Comparing the 1980s to the 1990s, the prevalence of Brazilian patients with hyperparathyroid bone disease (HP) increased from 32.3% to 44.0%, while Al overload decreased from 61.3% to 42.4%. A logistic regression analysis showed that the main factors associated with HP included female gender, age of less than 40 years, black patients, longer time on dialysis, and absence of Al overload. In Uruguay, HP also increased over time from 31.8% to 70.5% (P < 0.05), while Al overload decreased from 42% to 27% (P < 0.05).

CONCLUSION

A better control of Al overload may lead to a change in histologic pattern, as evidenced by the increasing prevalence of HP.