[Significance of sRANKL/OPG ratio in diagnosis of multiple myeloma bone disease].

This study was purposed to investigate the relationship between the levels of soluble receptor activator of nuclear factor kappa B ligand (sRANKL) and osteoprotegerin (OPG) in serum of the patients with multiple myeloma (MM) and multiple myeloma bone disease (MBD). The serum levels of sRANKL, OPG, tartrate-resistant acid phosphatase-5b (TRAP-5b) and C-terminal telopeptide of collagen I (CTP-I) which both are indexes for metabolism of osteoclast (OC) in newly diagnosed MM patients (n=42, experimental group) and healthy persons (n=25, control group) were detected by enzyme-linked immunosorbent assay. The roentgenography was used to determine bone damage in MM patients at the same time. According to these results acquired, the correlation of sRANKL/OPG ratio with levels of TRAP-5b/CTP-I, the incidence and degree of bone destruction were analyzed. The results indicated that the level of sRANKL (median value 9.33 microg/L) increased and level of OPG (median value 4.93 microg/L) decreased and the sRANKL/OPG ratio (2.65) increased significantly in experimental group. Compared with control group, the differences in all the corresponding indicators were statistically significant (p<0.05). The sRANKL/OPG ratio was closely related to levels of TRAP-5b (r=0.512, p<0.05) and CTP-I (r=0.481, p<0.05) in MM patients. After all patients in experimental groups were divided into group with bone destruction (n=29) and without bone destruction (n=13), the sRANKL/OPG ratio in the group with bone destruction was 5.13 and much higher than that in group without bone destruction (1.12) (p<0.05). A close correlation between the sRANKL/OPG ratio and degree of bone destruction (r=0.445, p<0.05) was acquired when all MM patients were divided into three groups according to degree of bone destruction, but no difference between the ratio and clinical classification and International Staging System (ISS) in MM patients was found. It is concluded that the sRANKL/OPG ratio in serum of MM patients is significantly elevated, which may be closely related to increase metabolism of OC along with the incidence and degree of bone destruction. In short, the sRANKL/OPG ratio can be used as a reference index for the diagnosis of MBD.