Autoantibodies produced in SLE can form immune complexes that deposit along the glomerular basement membrane and cause glomerular inflammation which leads to a nephritic syndrome. Rapidly progressive glomerulonephritis - This is a syndrome of the kidney that is characterized by rapid loss of kidney function (usually >50% decline in glomerular filtration rate (GFR) within 3 months) with glomerular crescent formation frequently seen on kidney biopsy. Without treatment, it will quickly lead to kidney failure and potentially death within months. This syndrome has numerous underlying causes that can also cause nephritic syndrome, so this may be more of an association than a cause. Infective endocarditis - Infection that affects the inner lining of the heart (endocardium) and can potentially cause a thrombus to form on one or more heart valves and, if left untreated, can cause septic emboli that can have many systemic effects, including deposition into the glomerulus, causing glomerulonephritis and nephritic syndrome. Cryoglobulinemia - Antibodies that are sensitive to the cold can become activated in cold conditions and cause an increase in blood viscosity (hyperviscosity syndrome) as well as forming immune complexes that can deposit in the small blood vessels and can cause nephritic syndrome when this occurs in the kidneys. Membranoproliferative glomerulonephritis (MPGN) - Another type of glomerulonephritis that is caused primarily by immune complex deposition in the glomerular mesangium and glomerular basement membrane thickening, which activates the complement cascade and damages the glomerulus. This damage leads to inflammation in the glomerulus and can present with a nephritic syndrome.
If positive, then the physician may order additional tests to determine which autoimmune condition is the cause and how best to treat it. Antiglomerular basement membrane (anti-GBM) antibody - If positive, this is highly indicative of Goodpastures syndrome and can be used to guide treatment. Antineutrophil cytoplasmic antibody (ANCA) - If positive, this indicates that there is likely an underlying vasculitis that may be causing the acute nephritic syndrome. Serum complement (C3 and C4) - Complement factors bind to antibodies to form immune complexes and a decreased serum complement level could indicate that the complement is being consumed at a higher rate due to the formation of immune complexes leading to deposition in the glomerulus of the kidney. Invasive testing
A kidney biopsy will provide a fully definitive diagnosis of nephritic syndrome and may also reveal the underlying cause of the nephritic syndrome depending on the underlying pathological process. On biopsy, a patient with nephritic syndrome would show inflammation of numerous glomeruli. Treatment
When a patient is confirmed to have nephritic syndrome, the main goal of treatment (regardless of the underlying cause) is to control elevated blood pressures and reduce active inflammation in the kidney itself. Most often, the patient will need to be admitted to the hospital for close monitoring to ensure the efficacy of treatment and make adjustments as needed.