Our two kidneys have a vital function: to filter and purify the waste produced by our body. Each contains between 800,000 and 1 million nephrons, microscopic filtration units. At their end is a glomerulus “a very elaborate structure that acts as a sieve”, explains Pr Fatouma Touré, head of the nephrology department at the University Hospital of Limoges and secretary-general of the French-speaking society of nephrology, dialysis and transplantation.

This glomerulus is very fragile. “We have a well-defined stock of them that cannot regenerate”, she points out.

Glomerulonephritis is due to an inflammatory and immunological reaction within these glomeruli. Several causes are possible:

– Antibodies, which in principle should be eliminated by the kidney, accumulate abnormally in the glomerulus and trigger the inflammatory process (Berger’s disease, extramembranous glomerulonephritis, etc.).

– Auto-antibodies attack the glomeruli themselves.

– Cytokines, inflammatory molecules, produced abnormally in excess, act on the cells that make up the glomerulus and modify their functioning.

The process that leads to glomerulonephritis is not always explained, and the disease can manifest itself in different forms.

– Sometimes glomerulonephritis starts spontaneously, without knowing why.

– The disease can also appear after a poorly treated infection, in particular bacterial angina. “The antibodies initially directed against streptococcus A, responsible for angina, attack the glomerulus. Fortunately, this type of post-infectious glomerulonephritis is becoming increasingly rare as bacterial angina is better and better managed,” observes the nephrologist.

– More frequently, glomerulonephritis is sometimes associated with an autoimmune disease (the patient’s own antibodies turn against his body), for example lupus. “In this case, kidney damage is a serious sign. You have to act quickly to stop the inflammation,” she insists.

Professor Touré’s answer is clear: “ glomerulonephritis is a serious condition”. Damage to the glomerulus, if not treated in time, can lead to chronic renal failure. At the terminal stage, there are only two solutions: dialysis or kidney transplantation. Fact, “Glomerulonephritis represents 20% of the 11,000 patients admitted each year for dialysis or kidney transplant patients”, she specifies.

The disease can affect people who, a priori, do not have kidney problems. But patients with autoimmune diseases (lupus, vasculitis, etc.) or rheumatoid arthritis and other inflammatory rheumatism have an additional risk. In them, monitoring of kidney function is recommended at least once a year through urine and blood tests and monitoring of blood pressure.

The disease progresses without painful symptoms. Nevertheless, several signs can give the alert:

– Arterial hypertension: the kidney no longer working normally, it no longer ensures the balance between water and salt in the body, which increases blood pressure.

– Edema, that is to say swelling in the ankles, due to water retention.

– An abnormal color of the urine: “The color ranges from dewy to very dark. In post-infectious glomerulonephritis, the urine can even take on the color of Coca-cola,” observes Professor Touré. This coloration is explained by the presence of blood in the urine.

– Foamy urine linked to the abnormal accumulation of albumin, a blood protein.

It all starts with blood and urine tests.

– “The urine dipstick will reveal abnormalities such as the presence of albumin and red blood cells. Their abnormal presence in the urine is a sign that the glomerulus is affected”, explains the nephrologist.

– Blood creatinine level assesses kidney function: “A rise in creatinine shows that the kidney is no longer doing its filtration job properly. »

– A kidney biopsy puncture: this examination makes it possible to make the definitive diagnosis. It is performed in the hospital, under local anesthesia. The doctor will remove a kidney fragment using a needle guided under ultrasound. “The analysis of this sample makes it possible to know what the type of underlying glomerulonephritis is and what its prognosis is”, observes Professor Touré.

Several types of treatment can be proposed in case of glomerulonephritis:

– Immunosuppressive drugs. “The idea is to lower the patient’s immunity to extinguish the inflammation”, explains the nephrologist. Among these treatments, the most classic is cortisone. In some cases, cyclophosphamide is used as an infusion.

These immunosuppressants used in high doses have side effects. Decreasing immunity increases the risk of viral or bacterial infections. This is why vaccination, in particular to protect against the flu, pneumococcal infections and the coronavirus (Sars-Cov-2), is strongly recommended for the patients concerned.

– Other possible treatments: monoclonal antibodies.“They specifically target molecules involved in the onset of glomerulonephritis. For example, certain proteins involved in the appearance of autoantibodies during lupus can now be specifically blocked”, explains Fatouma Touré.

These treatments are effective, provided that the glomerulonephritis has been diagnosed early enough, that is to say before the fibrosis of the kidney definitively affects its filtration functions.

There are no specific preventive measures. However, everyone can protect their kidneys on a day-to-day basis with simple lifestyle rules. Advice from Professor Touré:

– Do 30 minutes of walking a day,

– Limit salt intake in your diet,

– Limit excessive intake of proteins of animal origin (red meat),

– Treat any urinary tract infections to prevent them from getting worse,

– Avoid non-steroidal anti-inflammatory drugs that are toxic to the kidneys.