Results:
Clinical features
In group A, acute renal injury was the most common manifestation (35%), followed by nephrotic syndrome (27%), characterized by macroalbuminuria, hypoproteinemia, and edema, and also included simple hematuria and/or microalbuminuria (19%), chronic nephritis (15%)and lupus nephritis (4%). (Figure 1A.) Most patients in group B presented with CKD(55%) and NS(40%); Only one patient presented with lupus nephritis(LN) (5%).(Figure 1B.)
Pathological features
A total of 38 patients completed kidney biopsy, including 18 patients in group A and 20 patients in group B. IgAN(39%) accounted for the largest proportion of pathological types in Group A, followed by MN(17%), FSGS(11%) and Endocapillary proliferative glomerulonephritis(EPGN) (11%). (Figure 2A.) Among 20 patients in Group B, the most common renal pathologic type was IgAN(45%), followed by FSGS(25%) and MN (15%).(Figure 2B)(Figure 3.)
Serum C3 and the deposition of C3in kidney
The serum C3 level of 25 patients with COVID-19 associated kidney injury was measured. 80% of them had normal C3 level. Among 38 patients with COVID-19 associated kidney injury who performed kidney biopsy, 31.6% presented with C3 (-), 7.9% presented with C3 (+), 28.9% presented with C3 (++), and 31.6% presented with C3(+++).(Figure 3.)
Prognosis
Follow-up visits were conducted in 13 patients of Group A and 14 patients of Group B.Among the 13 patients in group A, 7 patients had partial remission of proteinuria, 5 patients had no remission, and 1 patient had increased proteinuria. Hematuria was partially remission in 5 patients, stable in 4 patients, and increased in 4 patients. Four patients had stable creatinine, three had increased creatinine, and one had decreased creatinine.Among 14 patients in group B, 6 patients had partial remission of proteinuria, 6 patients had no remission of proteinuria, and 1 patient had remission of proteinuria. Hematuria was partially alleviated in 6 patients, increased in 4 patients, and stable in 4 patients. Five patients had reduced creatinine and four had stable creatinine.(Table 1.)