Nephritis can produce glomerular injury, by disturbing the glomerular structure with inflammatory cell proliferation. This can lead to reduced glomerular blood flow, leading to reduced urine output (
oliguria) and retention of waste products (
uremia). As a result, red blood cells may leak out of damaged glomeruli, causing blood to appear in the urine (
hematuria). Low renal blood flow activates the
renin–angiotensin–aldosterone system (RAAS), causing fluid retention and mild
hypertension. As the kidneys inflame, they begin to excrete needed protein from the affected individual's body into the urine stream. This condition is called
proteinuria. Loss of necessary protein due to nephritis can result in several life-threatening symptoms. The most serious complication of nephritis can occur if there is significant loss of the proteins that keep blood from clotting excessively. Loss of these proteins can result in blood clots, causing sudden stroke. ==Diagnosis==