A 32-year-old man complains of recurrent hematuria since his youth. The hematuria typically occurs following upper respiratory tract infections. Vital signs are normal. Urinalysis shows proteinuria, hematuria, and a few red blood cell casts. Laboratory studies disclose normal levels of BUN and creatinine. The ANA and ANCA tests are negative. For the patient, which of the following patterns of IgA immunofluorescence would be expected in the renal biopsy?
IgA nephropathy (Berger disease) is caused by immune complexes of IgA, which are located within the mesangium, where they most likely activate complement through the alternative pathway. The diagnostic finding is mesangial staining that is more intense for IgA than for IgG or IgM.Diagnosis: Berger disease, IgA nephropathy
Granular capillary membrane deposition
Linear basement membrane staining
Mesangial deposition
Perivascular location
Kidney