Polycystic kidney disease

Autosomal dominant polycystic kidney disease of adults, or, as it is often called, polycystosis of the kidneys of adults, is a hereditary kidney disease characterized by the presence of multiple cysts in both kidneys. 

[1], [2], [3], [4], [5]

Epidemiology

This is the most common pathology from the group of polycystic kidney diseases. Its frequency in the population is approximately 1: 1000 population, which corresponds to the detection of about 6000 new cases of disease per year in countries such as Russia and the United States. The overwhelming majority of patients with polycystic kidney disease develop kidney failure. Among patients with uremia treated with chronic hemodialysis, patients with polycystic kidney disease averaged 8-10%.

[6], [7], [8], [9], [10], [11], [12]

Causes of the polycystic kidney disease

Polycystic kidney disease in adults is a genetically determined disease that is inherited by an autosomal dominant type. This means that the probability of developing the disease in children whose parents suffer from polycystic kidney disease is 50%. There is no difference in the inheritance of the disease, depending on whether the father or mother is the carrier of the pathological gene; Similarly, the disease is equally often transmitted to boys and girls.

Currently, three variants of mutations of the polycystic kidney gene are identified: 80-85% of patients inherit the polycystosis gene of the 1st type - the PKD1 mutation in the short arm of the chromosome 16; in 10-15% there is a polycystosis type 2 gene - PKD2 mutation in the chromosome 4. 5-10% of patients are diagnosed with a new (newly discovered and not yet deciphered) mutation of the gene. Localization of gene disorders affects the natural course of polycystosis in adults: the first type has the fastest rate of renal failure, while in the second and third types, the course of polycystosis is favorable and the development of terminal renal failure occurs after 70 years.

How does polycystic kidney disease occur in adults and the mechanism of cyst formation at the present time is not definitively determined.

As a result of an active study of the cellular mechanisms underlying the cyst formation, the following major links in this process were identified:

• proliferation of tubule cells, leading to their obstruction, dilatation and increased intracanal pressure;
• hereditary impaired dilatability of the basal membrane of the tubules, leading to dilatation of the tubule even at normal intrachannel pressure;
• excessive accumulation of fluid that can be associated with a violation of the polarity of the sodium pump and, as a consequence, with the entry of sodium into the cysts, and not into the blood, as well as with the production of epithelial cells of neutral fat cysts that promote the accumulation of fluid.

It is shown that a number of factors provoke the development of polycystic kidney disease. Among them, chemical and medicinal substances: insecticides, food preservatives, diphenylamine, all antioxidants, lithium preparations, alloxan and streptozotocin, a number of antitumor drugs, including cisplatin, etc. In patients having the polycystic gene, the effects of the above factors are manifested by the earlier development of clinical manifestations of the disease.

[13], [14], [15], [16]

Symptoms of the polycystic kidney disease

The symptoms of polycystic kidney are divided into renal and extrarenal.

Renal symptoms of polycystic kidney disease in adults

• Acute and permanent pain in the abdominal cavity.
• Hematuria  (micro- or macrohematuria).
• Arterial hypertension.
• Infection of the urinary tract (bladder, renal parenchyma, cysts).
• Nephrolithiasis.
• Nephromegalia.
• Renal failure.

Diagnostics of the polycystic kidney disease

The diagnosis of "polycystosis of the kidneys of adults" is based on a typical clinical picture of the disease and identifying changes in urine,  hypertension, renal failure in persons with hereditary heredity for kidney disease. Confirm the diagnosis of the clinical examination of the patient - the detection of palpation of enlarged tuberous kidneys (their value can reach 40 cm) and data of instrumental research. At the heart of instrumental diagnosis of this disease lies the detection of cysts in the kidney - the main clinical marker of polycystic kidney disease.

[17], [18], [19], [20], [21]

Treatment of the polycystic kidney disease

At the present stage, polycystic kidney disease in adults is not treated. In recent years (early 2000), attempts have been made to develop a pathogenetic approach to treatment, which considers this pathology from the standpoint of the neoplastic process. Treatment of mice with experimental polycystosis with antitumor drugs (paclitaxel) and tyrosine kinase inhibitor, inhibiting the proliferation of cells, led to inhibition of cyst formation and a decrease in the available cysts. These methods of treatment are tested in an experiment and have not yet been introduced into clinical practice.