Nephritis

Nephritis is inflammation of the kidneys and may involve the glomeruli, tubules, or interstitial tissue surrounding the glomeruli and tubules.^[1] Nephritis comes from Ancient Greek νεφρῖτις, from νεφρός "kidney" and -ῖτις, a feminine adjective ending.^[2]

Subtypes

By main location of inflammation

• Glomerulonephritis is inflammation of the glomeruli. Glomerulonephritis is often implied when using the term "nephritis" without qualification.
• Interstitial nephritis or tubulo-interstitial nephritis is inflammation of the spaces between renal tubules.

By cause

Nephritis is often caused by infections, toxins, and auto-immune diseases. It can be caused by infection, but is most commonly caused by autoimmune disorders that affect the major organs. For example, those with lupus are at a much higher risk for developing nephritis. In rare cases nephritis can be genetically inherited, though it may not present in childhood. However, teen girls have been known to be diagnosed with the condition.

• Pyelonephritis is inflammation that results from a urinary tract infection that reaches the pyelum (pelvis) of the kidney.
• Lupus nephritis is an inflammation of the kidney caused by systemic lupus erythematosus (SLE), a disease of the immune system.
• Athletic nephritis is nephritis resulting from strenuous exercise. It may result in proteinuria, hematuria and cylindruria.^[3] In most persons these are transient findings that disappear within hours to days after the end of exercise.^[3] The findings generally increase by increasing severity and duration of physical stress.^[3] Hematuria after strenuous exercise may also result from march hemoglobinuria, which is caused by trauma to red blood cells, causing hemolysis and resultant release of hemoglobin into the blood.

Complications

Nephritis is the most common producer of glomerular injury. It is a disturbance of 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.

Nephritis is a serious medical condition which is the eighth highest cause of human death. As the kidneys inflame, they begin to excrete needed protein from the 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.

Epidemiology

Disability-adjusted life year for nephritis and nephrosis per 100,000 inhabitants in 2004.^[4]

no data   less than 40   40–120   120–200

200–280   280–360   360–440   440–520

520–600   600–680   680–760   760–840

more than 840