TNFSF11 and rheumatoid arthritis: While serum RANKL changes have been reported in multiple myeloma [23], Paget’s disease [24], and rheumatoid arthritis (RA) [25], limited studies are reported in postmenopausal women where the correlations between RANKL and OPG with age and BMD have been investigated, particularly in Arabian ethnic groups such as Saudi Arabia where the prevalence of osteoporosis is increasing [26].