C4A and chronic kidney disease: Baseline laboratory data (at time of renal biopsy), including CBC, serum creatinine, estimated glomerular filtration rate (eGFR) according to the CKD-EPI equation, electrolytes, serum lipid profile, C‐reactive protein (CRP), autoimmune serology, serum C3 and C4 levels, serum albumin, serum total protein, erythrocyte sedimentation rate (ESR), urinalysis, and spot urine protein-to-creatinine ratio (UPCR) or 24‐h proteinuria (g/day) are shown in Table 1.