Linear regression analysis revealed a good correlation of serum IL-21 (ρ = −0.018, P = 0.016) and TNF-α (ρ = 0.006, P < 0.001) (Figure 4A and 4B) levels with serum creatinine (Cr), indicating that circulating cytokines could be a potential biomarker for monitoring renal dysfunction. The gene discussed is IL21; the disease is Abnormal renal physiology.