J Korean Soc Endocrinol.  2004 Aug;19(4):332-345.

Relationship between Serum Osteoprotegerin-Receptor Activator of NF-kappaB Ligand Levels and Bone Mineral Metabolism in Men

• Oh KW
• Yun EJ
• Rhee EJ
• Lee WY
• Baek KH
• Kang MI
• Park CY
• Ihm SH
• Choi MG
• Yoo HJ
• Park SW

Abstract

BACKGROUND: Osteoporosis is a growing health problem, not only in women, but in men also. Sex hormones and insulin-like growth factor-I (IGF-I) have been shown to be the major determinant in male bone metabolism. Osteoprotegerin (OPG) is a recently identified cytokine, which acts as a decoy receptor for the receptor activator of the NF- B ligand (RANKL). OPG and RANKL have been shown to be important regulators of osteoclastogenesis in animal models. The relationship between the OPG-RANKL system and male bone status in human populations is unclear. The aim of this study was to investigate the relationship between circulating the OPG-RANKL system and bone mineral metabolism in 80 Korean men.
METHODS
The subjects of this study were 80 men aged between 42 and 70 (mean age, 54.5 yr). The serum concentrations of OPG and RANKL were measured by ELISA. The serum concentrations of estradiol, total testosterone, IGF-I and biochemical markers of bone turnover were measured by standard methods. The bone mineral densites (BMD) at the lumbar spine and femoral neck were measured by dual energy x-ray absorptiometry.
RESULTS
A significant correlation was observed between the serum OPG/RANKL ratios and osteocalcin levels (r=-0.229, p<0.05). The serum OPG levels were significantly correlated to the femoral neck BMD (r=-0.227, p<0.05). The mean value of the serum OPG was found to be greater in patients with osteoporosis at the femoral neck (mean SD, 4.72.1 pmol/L) than in subjects with a normal BMD (3.30.9 pmol/L, p<0.05). The serum RANKL/OPG ratios were significantly positively correlated to the serum estradiol level (r=0.401, p<0.001). Also, there was a significant negative correlation between the serum OPG and estradiol levels (r=-0.288, p<0.05). In a multiple regression analysis, the BMI, serum OPG and RANKL levels, and the serum IGF-I level were identified as significant predictors of the femoral neck BMD. In another multiple regression analysis, only the serum estradiol level was identified as a significant predictor of the serum OPG level.
CONCLUSION
In conclusion, our data show that the serum OPG and RANKL levels are partly associated with bone mineral metabolism, and are related to the endogenous estrogen levels in human male populations. Therefore, the possibility exists that the OPG-RANKL system may be a mediator of the estradiol in male bone metabolism. However, there have been few study published on the relation between the serum OPG and estradiol levels in men. Further studies are needed to clarify this relationship

MeSH Terms

Absorptiometry, Photon
Biomarkers
Enzyme-Linked Immunosorbent Assay
Estradiol
Estrogens
Female
Femur Neck
Gonadal Steroid Hormones
Humans
Insulin-Like Growth Factor I
Male
Metabolism*
Models, Animal
NF-kappa B*
Osteocalcin
Osteoporosis
Osteoprotegerin
Spine
Testosterone
Estradiol
Estrogens
Gonadal Steroid Hormones
Insulin-Like Growth Factor I
NF-kappa B
Osteocalcin
Osteoprotegerin
Testosterone