Rapidly progressive glomerulonephritis

Definitions & Key takeaways

Rapidly progressive glomerulonephritis (RPGN) is a type of kidney disease characterized by a rapid loss of renal function, with characteristic glomerular crescent-shaped scars seen on renal biopsies. It is caused by inflammation and damage to the glomeruli, which can result from conditions like infections, immune disorders, and vasculitis.

Symptoms of RPGN can include blood in the urine, swelling in the legs and face, high blood pressure, and decreased urine output. The condition can progress rapidly, leading to kidney failure if left untreated. Treatment options may include immunosuppressive drugs to reduce inflammation, as well as a specific treatment for the underlying cause of the condition. If the renal failure becomes irreversible, dialysis or a kidney transplant are required.

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Introduction0:00–0:25

Crescentic glomerulonephritis, which is sometimes called rapidly progressive glomerulonephritis, is a type of nephritic syndrome, meaning it involves inflammation of the kidney’s glomeruli.
This inflammation ultimately causes a proliferation of cells in the Bowman’s space, which forms a crescent shape and this change leads to renal failure relatively quickly—within weeks to months.

Causes and types0:25–1:57

The development of crescents in Bowman’s space can happen in several ways. In some cases the it’s idiopathic, meaning there’s no identifiable cause.
When the cause is identifiable, though, it can be split into several types. Type I is caused by anti-glomerular basement membrane, or GBM, antibodies, antibodies that target the GBM.
Type I is associated with Goodpasture syndrome, which also involves pulmonary hemorrhages. Type II is immune-complex-mediated, meaning caused by immune complexes, composed of antigens and antibodies.
This might be the case with poststreptococcal glomerulonephritis, systemic lupus erythematosus, IgA nephropathy, and Henoch-Schonlein purpura.
And finally type III is known as pauci-immune, meaning little or no anti-GBM antibodies or immune-complex deposits. In these cases, often anti-neutrophilic cytoplasmic antibodies or ANCAs are in the blood, which are autoantibodies against the body’s own neutrophils.
Furthermore, you can break it down into the type of ANCA. C-ANCAs, or cytoplasmic ANCAs, are associated with Wegener granulomatosis.
P-ANCAs or perinuclear ANCAs on the other hand are associated with microscopic polyangiitis and Churg-Strauss syndrome, the latter of which can be distinguished by having granulomatous inflammation, which is when immune cells attempt to wall off a substance perceived as foreign, asthma, and eosinophilia Whatever the underlying cause is, the common feature is severe glomerular injury and the development of a crescent shape.

Pathology1:57–3:15

Typically, as a result of cell-mediated immunity as well as macrophage involvement, the glomerular basement membrane breaks.
This allows stuff circulating in the blood like red blood cells, which can then go on to get into the urine, called hematuria, more inflammatory mediators, plasma proteins, like complement C3b protein, and fibrin to pass through into the Bowman space.
Following this flood of stuff, more monocytes and macrophages enter the Bowman space, as well as parietal epithelial cells, which proliferate.
The presence of monocytes and macrophages, plasma proteins, fibrin, and parietal epithelial cells, lead to the expansion of the normally-thin epithelial layer of cells into a thick, characteristic crescent-moon shape.
Over time, this crescent may undergo sclerosis, or scarring, where it’s replaced by connective tissue. Ultimately, the glomeruli are severely damaged, and the kidneys lose their ability to filter blood effectively, which means the glomerular filtration rate goes down, and if left untreated, crescentic glomerulonephritis can quickly lead to acute renal failure.

Diagnosis3:15–3:56

On light microscopy, you’ll see the characteristic moon or crescent-shaped glomeruli in all three types. The three types, though, can sometimes differentiated on immunofluorescence.
For type I, the immunofluorescence pattern will be linear, since antibodies bind to collagen of the glomerular basement membrane.
For type II, the immunofluorescence pattern will be granular, as a result of immune complex deposition in the subendothelium.
Type III is actually negative on immunofluorescence, since remember it’s pauci-immune and there usually aren’t antibodies or immune-complex deposits in the glomeruli, but rather type III is associated with ANCAs in the blood.

Treatment3:56–4:22

Crescentic glomerulonephritis most often affects adults in their 50s and their 60s, and typically has a poor prognosis if not treated early.
Anticoagulants might be used to reduce fibrin buildup in crescent formation, and plasmapheresis is usually used in combination with immunosuppressants.
If the renal failure’s becomes irreversible, they might need dialysis or a kidney transplant. Alright, as a quick recap: crescentic glomerulonephritis is a type of nephritic syndrome that’s characterized by epithelial cell proliferation into a thick crescent or moon-shape, which leads to hematuria, decreased glomerular filtration, and can rapidly progress to renal failure.

Review4:22–4:50

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