Detailed view of the glomerulus - click to enlarge

The glomeruli are small structures composed of capillaries inside the Bowman's capsule, forming the nephrons in your kidneys. You have about a million of them, all working away filtering your blood. (Click the image on the left for a larger view, giving more details.) They are part of the basic filtration unit of the kidney, and thus are rather important to your health. When they become inflamed, you have Glomerulonephritis, also called glomerular nephritis, and sometimes shortened to GN. It can be caused by some problems with the immune system, but often the exact cause is unknown. It can arise after an infection (throat infections are often responsible), or be related to taking non-steriodal anti-inflamitory drugs.

It can develop rather quickly and leads to loss of kidney function over a period of weeks to months. For many people, this is their first encounter with renal failure. It is more common in children and young adults.

There may not be any obvious symptoms, but if the glomeruli get damaged, you can have traces of proteins or blood in your urine, often only confirmed by testing. But if the damage is more serious, your urine may be red or brown, cloudy or frothy. Fluid retention can cause swelling of your face, feet and legs. In severe cases, you may not be able to urinate for days at a time.

In mild cases, there may be no need for treatment, apart from regular monitoring of your condition. But in more serious cases, you will require a course of treatment with drugs.

The real problem becomes the resulting complications that can occur - high blood pressure, problems with other organs (if it is associated with an immune systems problem) and most worryingly, but luckily not commonly, kidney failure. Although glomerulonephritis can lead to kidney failure, the disease itself can be a temporary situation and is reversible with the proper treatment, and thus few complications. So if you suspect that you may have glomerulonephritis, do seek medical advice and ask for a urine test.