IgA nephropathy is the most common cause of glomerulonephritis worldwide with approximately 40% of afflicted patients progressing to chronic renal failure over the next two to three decades. This disorder is more frequent in certain parts of the world including China, Australia, Japan, and parts of Europe. However, this disorder may be underdiagnosed in the United States secondary to the higher threshold toward renal biopsy practiced by American nephrologists. Children and young adults are most frequently affected with a male predominance, but this disorder may be seen in persons of all ages and both sexes. There is a higher occurrence in persons of Native American ancestry from the New Mexico area. Currently, the cause of this disorder is unknown.

Classically, this disorder presents as macroscopic hematuria 1 to 2 days after an upper respiratory tract viral illness or as recurrent macroscopic hematuria without any identifiable inciting event or cause. However, this disorder is also a common cause of asymptomatic hematuria and proteinuria and therefore may be underdiagnosed because these abnormalities are often ignored when not symptomatic. The above-mentioned renal abnormalities may also be accompanied by nonspecific systemic symptoms such as fever, malaise, fatigue, and myalgias. Some persons manifest acute renal failure with the initial event but this usually resolves.

The diagnosis is made by renal biopsy, which shows IgA deposits in the renal mesangium on immunofluorescence microscopy. In this regard, Bergers disease is indistinguishable from Henoch-Schonlein purpura. Histologic features that are indicative of progression toward renal failure include glomerulosclerosis, interstitial fibrosis, and mesangial hypercellularity. Microscopic examination of the urine sediment will reveal dysmorphic red cells and red blood cell casts that are indicative of glomerulonephritis. Proteinuria is also noted on urinalysis testing and may even be in the nephrotic range.

The prognosis is variable. Some patients have a benign course whereas others progress to renal failure. Predictors of a poor prognosis include hypertension, severe proteinuria, decreased renal function, persistent microscopic hematuria, plus the above-mentioned histologic findings

Treatment for cure does not exist. Forms of treatment that may help slow disease progression include steroids, fish oil (12 gram/day of 30% concentrate of eicosapentaenoic acid and docosahexanoic acid), or ACE inhibitors versus ARBs. Renal transplantation is also used in severe cases. Disease recurrence in the donor kidney is common, but is not considered a contraindication to transplantation. It is of note that donor kidneys taken from patients with Bergers disease have successfully been transplanted with resolution of disease when given to persons not afflicted with IgA nephropathy.