GDF15 and Hematuria: SLE patients with hematuria had higher serum levels of GDF-15 than that in patients without hematuria [904.140 (589.491–1498.938) vs. 452.440 (253.513–691.203), P < 0.001; Figure 1B], and patients with high disease activity (SLEDAI ≥ 10) had much higher serum levels of GDF-15 than that in patients with less active disease activity (SLEDAI < 10) [727.972 (445.530–1374.793) vs. 306.506 (230.665–515.959) pg/ml, P < 0.001; Figure 1C].