an increasing trendP < 0.001
a decreasing trendP < 0.01
Results The serum levels of 25(OH)D, 25(OH)D3, and F25(OH)D showed a decreasing trend ( z = −2.781–−3.996, P < 0.01) in RA patients with CKD progression from mild to severe, while C3-epi-25(OH)D3 showed an increasing trend ( z = 6.741, P < 0.001) and 25(OH)D2 showed no significant difference among the groups ( z = 0.976, P = 0.329).