which are included here: Blood culture - This is the process where a sample of the patient's blood is sent to the microbiology lab to attempt to isolate and grow any bacteria that may be circulating in the blood, in order to identify the pathogen. This is helpful if the physician suspects infection as the underlying cause of the nephritic syndrome. Antinuclear antibody (ANA) titer - ANA is commonly positive in patients who have an underlying autoimmune disease, so this test is useful if the physician suspects an underlying autoimmune disease (refer to the Causes section above for examples) as the cause of the presenting 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 Goodpasture's 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. Some treatment modalities commonly used to meet these goals include: Bed rest during the recovery process to ensure administration of optimal medical therapy with as low of a risk as possible for any exacerbating factors (falls, infection, etc.). Fluid restriction to minimize the risk of edema (if not already present) or to reduce any active edema that may be present. A special diet during the hospital stay that restricts sodium, potassium,