What Causes Nephritic Syndrome?

The presence of red blood cells and proteins in the blood, associated with a sharp decrease in the ability to filter kidney, result in what is known as Nephritic syndrome.

• The kidney it is a viscera that fulfills four functions fundamental: eliminate waste products of nitrogen metabolism, regulate the balance of water and salts in the body, regulate the pH of the blood and form a series of hormones that control the production of red blood cells, the absorption of calcium and participate in the regulation blood pressure. The functional unit of these organs is the nephron and each kidney has about a million nephrons. They are made up of a series of tubules and a ball-shaped unit of capillaries called the glomerulus, which is where produces the filtering of the blood that reaches the kidney through the renal artery. When the glomeruli are injured by different causes, they they get inflamed, which impairs its ability to filter the blood and allows proteins and red cells from the blood to escape into the urine. These two facts is what is known as acute nephritic syndrome.

How is it produced?

When the glomeruli become inflamed, which are a set of capillaries arranged in the shape of a ball, they suffer a lesion in the wall, which allows the passage of plasma proteins and red blood cells into the urine. Likewise, when the purification capacity of the blood is diminished, oliguria occurs, a decrease in urine production, which in extreme cases can lead to the total absence of diuresis (anuria). This fact causes that nitrogenous substances accumulate in the blood, such as urea, which the kidney would eliminate under normal conditions, as well as a retention of water and salts, which means that, if the nephritic syndrome progresses, edema occurs that can be focal or generalized. In the same way, the fact of retaining liquids causes an increase in blood pressure, which can lead to a congestive heart failure, a failure of heart function due to an increase in the volume of fluid with which the heart must work.

Nephritic syndrome, the triad of proteinuria, hematuria and acute decrease in glomerular filtration rate, can have many causes, the most common being post-streptococcal glomerulonephritis, the inflammation of the glomeruli secondary to a strep infection. After a pharyngotonsillar or skin infection, complexes formed by antibodies and parts of the bacteria are produced that, deposited in the glomeruli, injure them and cause nephritic syndrome. It is usually more common in children and adolescents. Other bacterial infections That can cause (less frequently) a nephritic syndrome can be endocarditis, visceral abscesses, osteomyelitis, pneumonia or meningitis. Infections of viral origin, caused by parasites or fungi can also produce a nephritic syndrome.

Other causes of nephritic syndrome are primary glomerulonephritis, that is, those acute inflammations of the glomeruli that are not secondary to other causes such as infections or toxic substances. Among these types of glomerulonephritis, the extracapillary, membranoproliferative and mesangial stand out.

Nephritic syndrome and its symptoms appear frequently in kidney disease caused by systemic autoimmune diseases, diseases due to an alteration of the immune system that creates antibodies against its own tissues and that has repercussions on various organs and systems of the body. These diseases are the most common cause of nephritic syndrome in adults. The major autoimmune diseases Presenting with this syndrome are systemic lupus erythematosus, hemolytic uremic syndrome, Henoch-Schönlein purpura, cryoglobulinemia, necrotizing vasculitis, and Goodpasture syndrome.

Other kidney diseases that may present a nephritic syndrome in their development are certain kidney tumors, renal vein thrombosis, renal artery thromboembolism or kidney inflammation after radiotherapy or chemotherapy.

Symptoms

• Hematuria that occurs in nephritic syndrome can be seen with the naked eye (gross) or detected only on a urine test.
• Fluid retention causes edema to appear, especially at the eyelid level and predominantly in the morning. They can also occur on the rest of the face and lower extremities. This same fact leads to the appearance of blood pressure figures that can be high.
• The decrease in glomerular filtration leads to a decrease in the daily production of urine and a situation of, facts that are present most of the time, but that do not condition the prognosis of the situation.
• Other more general symptoms may appear, such as malaise, muscle and joint pain or headache, as well as other symptoms typical of the disease causing nephritic syndrome.

Diagnosis

Nephritic syndrome it is not usually diagnosed in isolation but in the context of the disease that causes it when it comes to systemic diseases, while in general it is diagnosed as an isolated entity in the case of nephritic syndrome secondary to post-streptococcal glomerulonephritis.

The diagnosis is clinical and based on laboratory findings. Hematuria can be seen in the urine sediment, where we will characteristically see hematic casts. Proteinuria is also seen in a 24-hour urine collection, although the losses are not of a high range, less than 2 grams per day.

In the blood test we can find alterations that can indicate the possible cause of the nephritic syndrome, such as anemia, a decrease in platelets or an increase in LDH in the case of hemolytic uremic syndrome, a decrease in lymphocytes and ANCA, ANA or antiphospholipid antibodies in the case of lupus erythematosus systemic or ASLO antibodies in post-streptococcal glomerulonephritis. In the latter case we can also perform bacterial blood cultures or throat or skin cultures in search of the causative bacteria.

Treatment

Treatment is based on that of the causative disease if it is diagnosed and treated and on the correction of the symptoms of nephritic syndrome: diuretics and correction of fluid retention, dietary and pharmacological control of blood pressure, or corticosteroids in case of that the cause is a systemic inflammatory disease. In cases of severe kidney failure, it may be necessary to undergo dialysis in order to supply kidney function.

There are not too many preventive measures for this syndrome, but it is always advisable to ensure an adequate intake of water, 1.5-2 liters per day, to promote proper kidney function.