Hemolytic uremic syndrome

Hemolytic uremic syndrome is a predominantly childhood disease characterized by the presence of acute renal failure, anemia, and decreased number of platelets. Mortality among affected children is between 5% and 15%, rising up to 30% in adults.

Hemolytic uremic syndrome is related to another entity known as thrombocytopenic thrombotic purpura, which is characterized by being more frequent in adults and presenting a lower degree of renal involvement than in the case of hemolytic uremic syndrome.

How is it produced?

Most of the time, the cause of this alteration is unknown. On many occasions, however, it occurs after a bacterial infection, especially by the enterohemolytic E. coli bacteria, although it has also been linked to other bacteria and some viruses. In children the picture may be preceded by a respiratory infection or bacterial gastroenteritis.

Likewise, it has been seen that there are other factors that may be related, such as certain drugs (mitomycin, contraceptives, cyclosporine, non-steroidal anti-inflammatory drugs), systemic diseases such as systemic lupus erythematosus, high blood pressure or scleroderma, or pregnancy complications and postpartum.

An injury occurs in the inner layer of the small renal arteries and arterioles, which leads to an activation of coagulation and an increase in the thickness of the wall of the glomeruli, which makes it difficult for the red blood cells to pass and can break them. Sometimes thrombi form inside these arterioles and small-caliber arteries.

Symptoms

Hemolytic uremic syndrome is characterized by the presence of a picture of acute renal failure, which shows a decrease in urine output (oliguria) that in advanced stages may disappear completely (anuria), as well as hematuria and a high elimination of protein in the urine, sometimes more than 3 grams a day. Due to kidney failure, high blood pressure can occur, which can be severe and difficult to manage pharmacologically. In the long term, due to the accumulation of urea in the blood, a state of anemia can occur.

Due to the alteration of the inner layer of the small vessels, the caliber of passage is diminished, so that the red cells, when passing, can break, with which an anemia occurs due to rupture of these red cells, which is known such as microangiopathic hemolytic anemia (due to rupture of red blood cells caused by injury to small vessels).

There is also a decrease in the number of platelets, a thrombopenia, which are consumed by depositing largely in the affected vessels. This lack of platelets and the consumption of clotting factors predispose the patient to hemorrhages, mainly at the cutaneous, retinal, nasal, hematuria level, in the upper digestive tract, with black and sticky stools that we call melena, or at the gynecological level.

Neurological changes are rare, occurring more frequently in the case of thrombocytopenic thrombotic purpura. If they do occur, they are usually in the form of disorientation and confusion, seizures and, as the disease progresses, coma. The presence of neurological symptoms in patients with hemolytic uremic syndrome conditions a poor prognosis.

Diagnosis

The diagnosis will be based on the symptoms of a child with symptoms of acute renal failure and with some blood and urine tests in which alterations typical of the disease are observed.

A blood test will show anemia with increased levels of urea, creatinine, bilirubin, and LDH. When studying the shape of the red blood cells, schistocytes will be seen, red bodies that are red blood cells that have broken as they pass through the affected vessels of the glomeruli. Alterations in clotting factors and platelet counts of 80,000-100,000 / ml will also be seen.

In the urine analysis, red blood cells and high levels of proteinuria will be seen.

Treatment

The treatment of hemolytic uremic syndrome is palliative and controls the symptoms and complications. Plasmapheresis, the external clearance of plasma from the blood, is used to rid it of certain substances, but while it works well in thrombocytopenic thrombotic purpura, the results in hemolytic uremic syndrome are not as promising.

The symptoms of kidney failure will be controlled with control of the intake of fluids and salts, an adequate diet and pharmacological treatment to control arterial hypertension. In cases of severe anemia, blood transfusions should be used. In advanced stages of kidney failure, the treatment of choice is dialysis or kidney transplantation.

Precautionary measures

There are no specific preventive measures for this disease, except for strict control of diseases that may be related to it, such as lupus or high blood pressure, and avoiding the inappropriate or unsupervised use of certain drugs.