Immune-complex glomerulonephritis

Immune-complex glomerulonephritis: IgA nephropathy, aka, Berger disease, is the most common primary glomerular disease. It is characterized by excessive circulating IgA, which deposits in the mesangium.

• The specific causes of this disorder are uncertain, but it's thought to have multi-hit origins with both genetic and environmental components.
• Notably, hematuria tends to occur after or during a respiratory illness.
• Prognosis is poor, and IgA nephropathy often leads to end-stage renal disease.

There is no cure for the disorder, but ACE inhibitors, ARBs, and corticosteroids are often used in supportive care. IgA vasculitis, aka Henoch-Schölein purpua, is characterized by IgA collection in the small blood vessels, which leads to inflammation and leakage. This disorder has multi-organ manifestations, and often produces a rash of purple spots where vessels under the skin leak blood (purpura).

• Most patients recover on their own, but some can develop chronic nephritis.
• Triggers for IgA vasculitis include infections, medicines, and foods.
• To learn more about small vessel vasculitis, please review here.

Some authors suggest that IgA nephropathy and IgA vasculitis are the same disease entity with varied clinical manifestations, given that both involve IgA deposits in the kidneys; why some patients also have systemic manifestations is unclear. Infection-related glomerulonephritis (aka, post-infectious glomerulonephritis) is a Type II hypersensitivity reaction to certain infections.

• In children, the reaction most often appears 2-4 weeks after Group A streptococcal infection (hence, it's often referred to as post-streptococcal glomerulonephritis).
• In adults, it most often occurs concurrently with Group A streptococcal or staphylococcus infections.
• Helpful diagnostic indicator: Approximately 90% of patients with infection-related glomerulonephritis have elevated anti-streptolysin O titer, which is indicative of a pervious streptococcal infection.
• A common histopathological finding is "humps" on the epithelial side of the glomerular basement membrane on electron microscope; however, these humps are found in other renal disorders and are not conclusive.

Lupus nephritis, which often co-exists with nephrotic syndrome, is also caused by immune-complex deposition in the glomeruli. There are 6 subtypes of lupus nephritis; details are this is beyond the scope of this tutorial.