The OPG/RANKL ratio in the regulation of osteoporosis associated with pregnancy and lactation

Objective: Changes in bone density and bone markers suggest that pregnancy is associated with poorer maternal bone mass. Calcium metabolism is restored to meet the needs associated with the construction of the fetal skeleton. The fetus contributes to this process by removing regulators from the placenta. Understanding of the entire process is limited, but some changes are clear. Aim: To study the influence of risk factors such as the OPG/RANKL ratio in the development of osteoporosis associated with pregnancy and lactation. Materials and methods: To fulfill the objectives of the study, we formed 2 groups of subjects. The first, main group consisted of 27 women who developed back pain during pregnancy and/or lactation and an MRI study revealed compression fractures of the vertebrae of various locations. The second, control group consisted of 14 women without fractures and complaints of back pain in the anamnesis. Results: A comparative analysis in the main and control groups showed that, depending on the activity of β-cross laps, the average OPG value in the main group of women with normal and increased bone tissue resorption was comparable. At the same time, the average RANKL values in the main group, in the subgroup with normal resorption, are significantly lower than in the group with increased resorption (92.8 ± 53.6 and 337.1 ± 168.5). The average RANKL values in the control group and in the subgroup with normal resorption are also lower than in the group with increased resorption (65.4±23.1 and 99.8±40.7). A comparative analysis of the OPG/RANKL ratio in the main group, in the subgroup with normal resorption was 3 times higher than in the subgroup with increased resorption and amounted to 0.0075; 0.0026 respectively. At the same time, in the control group there were no differences in subgroups. The OPG/RANKL ratio in women of the main and control groups with normal resorption was 3.2 times higher, and in the group with increased resorption this ratio was 7.3 times higher (0.0075 and 0.024; 0.0026 and 0.019). Conclusion: In general, all effects on the state of bone tissue metabolism are realized through the main regulatory systems of osteoblastogenesis (canonical wnt signaling pathway) and osteoclastogenesis (RANKL/RANK/OPG). Changes in the expression of molecules that regulate osteoblastogenesis and osteoclastogenesis with age and due to the negative influence of other factors lead to a decrease in bone strength, which can be manifested by a decrease in bone mass, BMD and/or disruption of internal microarchitecture and, as a result, fractures with minimal trauma.