DKK1 and rheumatoid arthritis: Findings revealed 1) that the MSTN/FSTN ratio and serum levels of Dkk1 were significantly lower whereas PSTN values were elevated in RA patients when compared with controls, 2) physical functioning of RA patients was found to be impaired in some functional tests and 3) there were significant correlations between the endocrine factors MSTN and FSTN and physical function tests.