The aim of the study was to evaluate the influence of the intensity of mesangial C3 deposits in kidney biopsy and the serum C3 level on the clinical course and outcomes of IgAN in children. The study included 148 children from the Polish Pediatric IgAN Registry, diagnosed based on kidney biopsy. Proteinuria, creatinine, IgA, C3 were evaluated twice in the study group, at baseline and the end of follow-up. Kidney biopsy was categorized using the Oxford classification, with a calculation of the MEST-C score. The intensity of IgA and C3 deposits were rated from 0 to +4 in immunofluorescence microscopy. The intensity of mesangial C3 > +1 deposits in kidney biopsy has an effect on renal survival with normal GFR in children with IgAN. A reduced serum C3 level has not been a prognostic factor in children but perhaps this finding should be confirmed in a larger group of children.

Immunoglobulin A nephropathy (IgAN) is one of the most common forms of glomerulonephritis and one of the main causes of end-stage renal disease (ESRD), affecting up to 40% of patients after 20 years of the disease. Over the past few years, several studies have been conducted to search for biomarkers that can diagnose IgAN in a non-invasive way, select patients in the asymptomatic phase, assess the progression of the disease process and monitor its efficacy, and assess the risk of IgA nephropathy progression. Non-invasive investigations using molecules as an alternative to renal biopsy have potential relevance for diagnosis, the determination of treatment efficacy and the assessment of disease activity. For the early screening of IgAN with isolated haematuria, these factors may be useful for early intervention and result in a reduction in the risk of impaired renal function. The clinical studies discussed in this review underline that featured molecules show potential as biomarkers for the diagnosis and assessment of disease progress in IgAN.

Objective: The aim of the study was to evaluate the clinical course and risk factors of venous thromboembolic complications (VTEC) in children with a first episode of steroid-sensitive nephrotic syndrome (SSNS). Materials and methods: We retrospectively analyzed the medical records of children hospitalized due to SSNS in one pediatric nephrology unit between 2012 and 2019. Demographic data, clinical symptoms at the onset of NS, and laboratory parameters were compared between patients with and without VTEC. Results: Among 106 children (4.7 +/- 3.06 years of age) with a first episode of SSNS, 5 VTEC were diagnosed during 2 - 60 days after onset of NS, on the basis of clinical symptoms and/or results of imaging studies. These were thromboses of femoral vein, central part of the kidney, dorsal veins of the hand, venous sinuses of the brain, and superficial vein in the popliteal fossa region. We found significant higher serum fibrinogen level (p = 0.022) and D-dimers (p = 0.0001) in children with VTEC vs. those without VTEC, but AUC analysis showed that only D-dimers significantly differentiate thrombosis. The clinical risk factors of VTEC were vascular cannulation (100%), infections (80%), and diuretics (80%). In children with VTEC, low molecular weight heparin was used. The outcome was a full recovery in all patients. Conclusion: VTEC occurs in 4.72% of children with a first episode of SSNS. The course of VTEC in children with SSNS may be asymptomatic. The clinical risk factors of VTEC in children with SSNS are vascular cannulation, infections, and diuretics. High D-dimer levels are a sensitive indicator of thrombosis.