Etiology

The most frequent causes:

- glomerulonephritis (30 %);

- pyelonephritis (20 %);

- polycystic disease (10 %);

- systemic disease with renal injury (8 %);

- hereditary nephropathies (10 %);

- tumor of the kidney (5 %);

- other pathology (7 %);

- unknown etiology (10 %).

Pathogenesis

In chronic renal failure define not only decrease of nephrones quantity but also significant remodeling of the last one (hypertrophy and dilation). The process develops step by step - from latent functional incompetence to significant uremia. Accordantly to renal failure progression increase impossibility of kidney for metabolic products excretion that leads to their accumulation in organism.

Metabolic disorders complicated by uremia intoxication that leads to: nitrousemia, anemia, osteodystrophy, acid-alkaline disbalance, arterial hypertension, hemorrhagic syndrome and immune deficiency.

The clinic of chronic renal failure augments gradually with slowly changes of homeostasis: increase concentration of creatinin and uric acid in plasma, levels of guanidine acid, sulfates, phosphates and other metabolites. Metabolic acidosis develops. With oliguria advance patient's condition becomes worth: hurriedly increase nitrousemia and acidosis, decrease sodium, calcium and chloral level with hyper concentration in plasma of magnum and potassium. Combination of those impairments lays in the basis of renal failure symptoms.

Classification of chronic renal diseases (nkf, usa)

Stage	Characteristic	Glomerular filtration rate (GFR, ml/min/1.73 m2)	Recommendation
	Risk factors presence	More than 90	Observation, risk factors correction
I	Renal damage with normal or decreased GRF	More than 90	Lowering of risk progres-sion of the main desease
II	Renal damage with insignificant decreased GRF	60-89	Lowering of risk progres-sion of the main desease and cardiovascular compli-cations
III	Moderate degree of GRF decreasing	30-59	Complications treatment
IV	Significant degree of GRF decreasing	15-29	Preparing to replacement therapy
V	Chronic renal failure	Less than 15 or dialysis	Replacement therapy

Clinical features

Intensity of chronic renal failure clinical sings, particularly in the initial stage, depends on the etiologic factor. Within disease progression, differences in clinical picture become smoothed and complaints explained by intoxication via abnormal nitrogen metabolism.

Depending on disease particularities the primary position obtains the next clinical symptoms and syndromes:

- affection of the cardiovascular system: arterial hypertension, pericarditis, uremic cardiomyopathy, arrhythmias and acute left ventricular failure;

- gastro-intestinal syndrome: mucosa injury - cheilitis, glossitis, stomatitis, esophagitis, gastritis, enteritis, colitis, gastric and intestinal ulcer; organic glands damage (parotisis, pancreatitis);

- neurological syndrome and central nervous system damage: uremic encephalopathy: symptoms of asthenia (fatigue, memory impairments, irritation, dreadful sleeping); symptoms of depression (bad mood, decreased mental activity, suicidal ideas); phobias, changes of character and conduct (emotional weakness, indifference, eccentric conduction); deranged consciousness (stupor, sopor, coma), vascular complications (hemorrhagic or ishematic stroke); uremic polyneuropathy: small paresis and paralysis, other changes of felling and moving function;

- endocrine syndrome: endocrine pathology (hyperparathyreoidism, loss of libido, impotencies, impairment of spermatogenesis, hynecomastia, olygo-and menorrhea, sterility); pain and muscular weakness, cramps, proximal myopathy, aseptic bones necrosis, arthritis, intra and subcutaneous calcina-tis, accumulation of urine crystals in the skin, ammonium smelling from the mouth and hyperlipidemia);

- anemic-hemorrhagic syndrome: anemia (normochromic, sometimes erythro-poetin deficient or iron deficient), lymphopenia, non-significant thrombocytopenia; clinical symptoms (pale color of the skin and visible mucosa with yellowish tint, eruption and dryness of the skin, hemorrhage lesions;

- affection of immune system: intercurrent infections, decrease of immunity.

There are such signs of chronic renal failure according to the periods:

/. The early signs of chronic renal failure:

1. Clinical: polyuria, nocturia, arterial hypertension, hypochromic anemia;

2. Laboratory: decrease of concentrated and filtrated function of kidneys.

//. The late signs of chronic renal failure:

1. Laboratory: nitrousemia (increased creatinin level, ammonium and urine acid concentration in plasma);

2. Instrumental: decrease of both renal size and cortex according to ultrasound examination and uroroentgenogram.