A DIAGNOSTIC CHALLENGE CASE REPORT: C3-GLOMERULONEPHRITIS IN A 17-YEAR-OLD ADOLESCENT

Introduction:

C3 glomerulonephritis is a rare immune-mediated disease caused by congenital or acquired disorders of the alternative pathway of the complement system, debuting with the hematuria, proteinuria or acute kidney injury. The heterogeneity of the clinical picture determines the difficulty of diagnosing the disease. In particular, differentiating it from clinically similar infectious related glomerulonephritis (IRGN). 

Methods:

Clinical observation of a patient with hematuria, nephrotic-level proteinuria, and an episode of acute kidney injury. 

Results:

A 17-year-old teenager developed face and upper extremities swelling, vomiting, and an increase in blood pressure to 154/104 mm Hg after an episode of acute respiratory viral infection. He was hospitalized at his place of residence with suspected acute intestinal infection. During examination: an increase in creatinine to 368 μmol/l, dyslipidemia was discovered. The blood total protein and albumin are normal, proteinuria 8 g / day. Based on the clinical picture and laboratory data, an IRGN was assumed, also the onset of systemic lupus erythematosus and C3 glomerulonephritis was not excluded. During additional examination, markers of systemic pathology are negative; PLAR and IgG4 are normal; a transient decrease in complement C3 was noted; an increase in D-dimer; eGFR CkiD U25 - 46.2 ml / min / 1.72 m2. C3 glomerulonephritis could not be excluded because of negative systemic pathology markers, the levels of PLAR, IgG4 and complement C3 in the patient. Therefore prednisolone 60 mg/day was prescribed. A kidney biopsy was performed: pronounced mesangial proliferation, 53% fibrous cell crescents, abundant deposition of IgG, IgA, C3 in the mesangium and periphery of capillary loops, IgA, C1q - traces. According to electron microscopy (EM) - a picture of mesangioproliferative glomerulonephritis with deposits of various localizations: intramembranous, paramesangial and subpodocytic. There is no data for membranous glomerulonephritis. IRGN and focal segmental glomerulonephritis were excluded. A genetic study is in progress. Taking into account the anamnesis, kidney biopsy and EM, C3 glomerulonephritis was confirmed in the teenager. Immunosuppressive therapy was initiated - MMF at a dose of 900 mg / m2, pulse therapy with methylprednisolone, prednisolone 40 mg / 48 h. There was a pronounced positive dynamic, stabilization of renal function (eGFR CKiD U25 80 ml / min / 1.72 m2) and a decrease in proteinuria to 2 g / day.

Conclusions:

A transient decrease in the C3 complement component can occur both in C3 glomerulonephritis and in acute post-infectious glomerulonephritis, which can significantly complicate diagnosis and increase the time before the start of therapy. In the absence of a clinical response to standard steroid therapy, it is necessary to exclude C3 glomerulonephritis even with a normal C3 level by conducting a morphological study of the renal tissue. Pathognomonic for C3 glomerulonephritis is intramembranous deposition in the glomerular basement membrane by electron microscopy. 

I have no potential conflict of interest to disclose.

I did not use generative AI and AI-assisted technologies in the writing process.