(characterized by dark brown or red colored urine), and edema of the hands, feet, and/or face. Post-streptococcal glomerulonephritis (PSGN) - Similar to IgA nephropathy, post-streptococcal glomerulonephritis (PSGN) most often occurs in children who have recently had an upper respiratory infection (URI). In contrast with IgA nephropathy, however, PSGN typically presents 2–3 weeks after recovering from an URI that was caused specifically by a Streptococcus bacteria. The symptoms at onset are very similar to IgA nephropathy and include abdominal pain, hematuria, edema, and oliguria. Henoch–Schönlein purpura (HSP) - Often considered a systemic form of IgA nephropathy, Henoch–Schönlein purpura (HSP) is a systemic small-vessel vasculitis that is characterized by deposition of IgA antibody immune complexes in different key areas throughout the body. Most often, the condition presents in children with palpable purpura, abdominal pain, and arthritis. When the kidneys are affected, the IgA immune complexes deposit in the glomerulus very similarly to IgA nephropathy and will present in a similar way. Hemolytic uremic syndrome - Most cases occur immediately following infectious diarrhea caused by a specific type of E. coli (O157:H7). The bacteria produces a toxin that causes widespread inflammation and numerous blood clots in small blood vessels (thrombotic microangiopathy). When the inflammation reaches the kidney, or the by-products of systemic inflammation build up in the kidney, the patient will begin showing signs of nephritic syndrome or potentially acute kidney failure (elevated creatinine, BUN, etc.). Adults Goodpasture syndrome - This is a rare autoimmune disease where autoantibodies are produced that target the glomerular basement membrane in both the lungs and the kidneys. The damage to the basement membrane causes bleeding, and the disease often presents in patients as hematuria and haemoptysis (coughing up blood). If not treated promptly with plasmapharesis to remove the autoantibodies, it can lead to permanent damage in the lungs/kidneys. Systemic Lupus Erythematosus (SLE) - Better known as simply "Lupus", this autoimmune disease can affect nearly every major system in the human body and the kidneys are no exception. 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