Renal amyloidosis – state and urinalysis
Amyloidosis is renal their dystrophic defeat, caused a deep breach (perversion) protein metabolism.
There are primary, or idiopathic, and secondary amyloidosis. For the primary amyloidosis is characterized by skin lesions, muscle, of the circulatory system, part of the alimentary canal. The cause of secondary amyloidosis consider various chronic infections - tuberculosis, syphilis, malaria, long purulent processes in the lung, osteomyelitis, myeloma and other diseases. For secondary amyloidosis typically loss of parenchymal organs - the spleen, kidney, liver, adrenal. There are several forms of family amyloidosis, inherited and recessive, and the dominant type. At the heart of the family amyloidosis, apparently, are genetic disorders, Related fermentopathy.
Amiloidoz, resulting in the tissues with the pathological process, It is a complex glycoprotein, in which fibrous and globular proteins, closely associated with polysaccharides.
Contents in amyloid glycine, alanine, leucine, valina, tirozina, histidine and other amino acids differ from the contents of collagen and hyaline. The amyloid proteins found, similar in its properties to α elektroimmunoforeticheskim1, b- и c-глобулинам, and albumin, fibrinogen, neuraminic acid.
The carbohydrate component consists of galactose and glucose, smaller amounts of galactosamine, glikozaminov, mannose, fructose and sometimes from hyaluronic acid, chondroitin sulfate and heparin. All the protein and carbohydrate components are firmly bound, amyloid and giving stability to various influences.
An important role in the formation of amyloid immunological mechanisms play. So, found, that the primary amyloidosis is marked tendency to increase the content of IgD (in 50% cases), the secondary - IgM (in hereditary amyloidosis these statements without deviation from the norm). Particularly distinct changes in all forms of amyloidosis occur in cellular immunity, primarily in T-system. There lymphopenia with lymphocyte depletion of lymphoid organs (lymph nodes, spleen, thymus, intestines). All patients with amyloidosis, regardless of the stage of the disease marked decrease in the number of T-lymphocytes, sometimes pronounced, and B-lymphocytes.
Significant changes in T-affect the immune system and its controlling effect on the function of B-cells, especially belkovoobrazuyuschuyu. Since the number of B-cells, carrying on its surface normal immunoglobulins, decreases, it is not excluded, in that the total pool of B-lymphocyte cells increases the amount, synthesizing a protein SAA (serum amyloid precursor), or other proteins, going to the construction of amyloid, or fragments of immunoglobulin molecules (l- or χ-circuit). The appearance of blood precursor protein, and then amyloid fibrils in tissues contributes to further suppression of T-cell immune system. It creates a vicious cycle, conditioning progression of the process.
In the early stages of the disease amyloid is deposited in the kidney parenchyma is gradually, since the renal pyramids, then proceeds to cortex, vessels, Taurus balls pochechnыh. Swollen epithelial tubules nefronov, grained, often desquamated. The cortex and medulla are large lymphoreticular infiltration.
Amyloid deposition in the glomeruli of the renal glomerular cells contributes to damage the filter, the consequence is the increased filtration protein. Develops relative kidney failure, clinically manifested in the appearance of proteinuria. It proteinuric stage amyloidosis, during which, in response to loss of protein appear edema, hypercholesterolemia, It lowers blood pressure - there is a typical nephrotic syndrome (edematous hypertensive stage). At this stage most of the glomerular amyloidosis observed with off glomerular capillaries, although there are glomeruli, where relatively little amyloid. Amyloidosis sclerosis and renal pyramids and the inner zone of the medulla often have diffuse. Many amyloid is deposited in the walls of arteries, Veins, lymphatic vessels. Observed hyaline droplet, hyaline vacuolar, vakuolynaya and zhirovaya dystrophy, necrosis and desquamation of epithelial tubules of nephrons, the accumulation of lipids in the stroma of the kidney. Infiltration of the kidney lipids suggests joining nephrotic syndrome.
With the accumulation of amyloid and the development of fibrosis and sclerosis appear azotemia and uremia (azotemicheskaya stage).
When amyloid-contracted kidney revealed the death of the majority of nephrons, they atrophy and interstitial tissue proliferation.
The main clinical symptom of the disease is proteinuria, swelling, hypoproteinemia, Renal hypertension and hypercholesterolemia. Proteinuria is developing all forms of amyloidosis, reaching the height of the disease 10-15 g / l. During the day stands out from the 2 20-40 grams of protein. The bulk of the urine protein constitute globulins. Among them are often identified β- и c-глобулины, реже a1– и a2-globulins, and fibrinogen. It is not excluded urinary excretion, especially when attached to amyloidosis nephrotic syndrome, protein SAA, relative molecular mass not over 100000. Maybe, This explains the low level of the protein in the serum of patients with primary and secondary, complicated with nephrotic syndrome, amiloidozom. Can be detected and the main faction of glycoproteins. Particularly significant excretion α1– и c-гликопротеидов. Globulinuriya gradually leads to a decrease in the albumin-globulin ratio urine, which may indicate the progression of amyloidosis, sometimes believable, than the increase in proteinuria.
Severity and duration of proteinuria It leads to the development and the appearance of edema gipoproteinemii, that in patients with amyloidosis occur quite early and can be widespread and persistent, remained significant even in the terminal uremic period. Along with hypoproteinemia observed Dysproteinemia, characterized by a change in the ratio of plasma proteins. Usually, there is an increase α2– and γ-globulin serum; You can detect an increase in α glycoproteins1– and β-fractions with a simultaneous decrease in albumin glycoproteins. Along with dysproteinemia often marked acceleration of erythrocyte sedimentation rate and changes in sediment samples (thymol, sublimate and others.).
Often a sign of amyloidosis is giperlipiduriya, combined with massive proteinuria, hypoproteinemia, dysproteinemia and swelling characteristic of classic nephrotic syndrome.
When immunoelectrophoresis revealed an increase in serum IgA and IgM and IgD reduction of complement.
If you suspect renal amyloidosis as a diagnostic test used test for amyloidosis with methylene blue, which is as follows. The patient is allowed to swallow 0,01 g of methylene blue in a gelatin capsule. Urine is collected prior to receiving (the control portion) and by 2, 3, 4 hours after ingestion of the capsule. The sample is considered positive, if the second and third portions of urine after taking capsules have slightly green color. A positive sample is observed at nephrosclerosis and renal amyloidosis with renal failure. In the absence of kidney damage after taking the capsule stained blue-green color of all three portions of urine.
The amount of urine in amyloidosis first decreases (oligurija), and its relative density is increased to 1,030 and more. Further, the number and the relative density of urine vary with the progression of.
The precipitate is usually scanty urine, but "dumb" sediment is no longer considered a pathognomonic sign of amyloidosis. Microscopic examination of sediment found in amyloidosis isolated white blood cells and red blood cells, generally unchanged (mikrogematuriâ), hyaline and sometimes granular casts. Upon accession, the nephrotic syndrome in urine sediment noted many of the cellular elements: leukocytes - 20-40, unmodified erythrocytes - 3-10 under the microscope. There kidney epithelial cells with a granular, adipose, hyaline droplet degeneration and vacuolation. Cylinders hyaline, epithelial, grainy, fat-grained, hyaline droplets, waxy, vacuolated. Blood and buropigmentirovannye cylinders for this disease are not typical. The urine can reveal cholesterol crystals, Needle fatty acids and lipid droplets.
