Osteoprotegerin in serum as a novel marker of bone metastatic spread in prostate cancer.

Passing–Bablok analysis showed that results obtained with the two chromogens were correlated. The Bland– Altman difference plot (Fig. 1) showed that eight of the paired values were outside of the 95% confidence interval (Ϫ2.6 and 4.2). These values fell nearly within the limits of agreement, and medical acceptance remained possible. The determination of low HIC with ferene gave better sensitivity (0.333 vs 0.215) and a lower detection limit (0.15 vs 0.30 ␮mol/L) than with bathophenanthroline. Moreover, this chromogen is less expensive than batho-phenanthroline. In conclusion, ferene, which is less expensive than bathophenanthroline sulfonate, slightly improves the sensitivity of the colorimetric measurement of low HIC. Ferene can beneficially replace bathophenanthroline sul-fonate in HIC determinations as recommended by the ICSH for serum iron (8).erin deposition in portal endothelial cells is a histological marker predicting poor response to interferon-␣ therapy in chronic hepatitis C. hepatic iron concentration: evaluation of two complementary methods, colorimetric assay and iron histological scoring. al. A systematic evaluation of bathophenanthroline, ferrozin and ferene in an ICSH-based method for the measurement of serum iron. Comparison of several regression procedures for method comparison studies and determination of sample sizes. Application of linear regression procedures for method comparison studies in clinical chemistry. Prostate cancer (PCa) is the most frequent carcinoma in men and is often complicated by skeletal metastasis (1). Because bone scintigraphy, the standard method of monitoring metastatic bone involvement, is expensive, lacks specificity, and is not particularly suitable for the follow up of patients, various metabolic bone markers have been studied as indicators for bone metastasis in PCa patients (2, 3). Markers that reflect osteoblast proliferation , e.g., skeletal alkaline phosphatase (sALP), are reportedly useful, which is consistent with the osteoblastic reactions seen in the skeletal metastases (4). The balance between osteoblastic and osteoclastic activity in bone is essentially influenced by osteoclastogenesis. The latter is regulated by three proteins: receptor activator of nuclear factor-␬B (RANK), which is expressed on osteoclast precursor cells; its ligand (RANKL), which is expressed on the surface of preosteoblastic and stromal cells; and osteoprotegerin (5, 6). The interaction of RANKL with RANK stimulates the differentiation of osteoclasts, whereas osteoprotegerin blocks this process by functioning as a decoy receptor for RANKL. This novel cytokine system appears to play an important role in the establishment of bone metastases in PCa patients (7). Osteoprotegerin has recently been found to be overex-pressed in bone metastases of these patients (8). This …