Microscopic examination of urine sediment
Microscopic examination of urine sediment is an integral and most important part of the general clinical study. There are elements of organized and unorganized precipitation of urine. The main elements of the organized sediment include erythrocytes, leukocytes, epithelium and cylinders;unorganized - crystalline and amorphous salts.
Epithelium. In healthy people in the urine sediment, single cells of the flat( urethra) and transitional epithelium( pelvis, ureter, bladder) are found in the field of vision. Renal( tubule) epithelium in healthy people is absent.
■ Flat epithelium. In men, only single cells are normally detected, their number increases with urethritis and prostatitis. In the urine of women, flat epithelial cells are present in greater numbers. Detection in the urine sediment of the flat epithelial beds and horny scales is an unconditional confirmation of squamous metaplasia of the urinary tract mucosa.
■ Transitional epithelial cells may be present in a significant amount in acute inflammatory processes in the bladder and renal pelvis, intoxications, urolithiasis and urinary tract infections.
■ Cells of the epithelium of the urinary tubules( renal epithelium) appear in nephritis, intoxications, circulatory insufficiency. In amyloidosis of the kidneys in the albuminuric stage, the renal epithelium is rarely detected, in the edema-hypertonic and azotemic stages-often. The appearance of epithelium with signs of fatty degeneration in amyloidosis indicates the attachment of the lipoid component. The same epithelium is often detected with lipid nephrosis. The appearance of the renal epithelium in a very large amount is observed with necrotic nephrosis( for example, with the poisoning of sulem, antifreeze, dichloroethane, etc.).
Leukocytes. Normally absent, or single in the drug and in the field of vision. Leukocyturia( more than 5 leukocytes in the field of view or more than 2000 / ml) can be infectious( bacterial inflammatory processes of the urinary tract) and aseptic( with glomerulonephritis, amyloidosis, chronic renal transplant rejection, chronic interstitial nephritis).Piuria is considered to detect 10 micromolar leukocytes in high-resolution microscopy( x400) in the field of vision in the sediment obtained by urine centrifugation, or in 1 ml of non-centrifuged urine.
Active leukocytes( Stringeimer-Malbin cells) are normally absent."Live" neutrophils penetrate into the urine from the inflamed renal parenchyma or from the prostate. Detection of active leukocytes in the urine indicates an inflammatory process in the urinary system, but does not indicate its localization.
Erythrocytes. Normally, there is no urine in the sediment, or single in the preparation. When detecting erythrocytes in urine, even in small amounts, further observation and repeated studies are always necessary. The most common causes of hematuria are acute and chronic glomeres-lonephritis, pyelitis, pyelocystitis, chronic renal failure, renal injury, bladder, urolithiasis, papillomas, tumors, tuberculosis of the kidneys and urinary tract, overdose of anticoagulants, sulfonamides, and urotropine.
Cylinders. Normally, the urine sediment can be hyaline cylinders( single in the preparation).Granular, waxy, epithelial, erytrocytic, leukocyte cylinders and cylindroids are normally absent. The presence of cylinders in the urine( cylindruria) is the first sign of a reaction from the kidneys to a common infection, intoxication, or to the presence of changes in the kidneys themselves.
■ Hyaline cylinders are composed of a protein that gets into the urine due to stagnant phenomena or an inflammatory process. The appearance of hyaline cylinders, even in a significant amount, is possible with proteinuria not related to renal damage( orthostatic albuminuria, stagnant, associated with physical exertion, cooling).Hyaline cylinders often appear in febrile states. Almost constantly hyaline cylinders are found in various organic lesions of the kidneys, both acute and chronic. Parallelism between the severity of proteinuria and the number of cylinders is not( depends on the pH of urine).
■ Epithelial cylinders are oblique and "glued together" epithelial tubule cells. The presence of epithelial cylinders indicates a lesion of the tubular apparatus. They appear in nephroses, including, as a rule, in a significant number with nephron necrosis. The appearance of these cylinders in nephritis indicates the involvement of the canal apparatus in the pathological process. The appearance of epithelial cylinders in the urine always indicates a pathological process in the kidneys.
■ Granular cylinders consist of tubular epithelial cells and are formed when expressed in the epithelial cells expressed degeneration. The clinical significance of their detection is the same as that of epithelial cylinders.
■ Wax-shaped cylinders are found with severe lesions of the kidney parenchyma. Most often they are detected in chronic kidney diseases( although they can appear with acute lesions).
■ Erythrocyte cylinders are formed from accumulations of erythrocytes. Their presence indicates a renal origin of hematuria( they are found in 50-80% of patients with acute glomerulonephritis) [Ryabov SIet al., 1979].It should be borne in mind that erythrocyte cylinders are observed not only in inflammatory diseases of the kidneys, but also in renal parenchymal hemorrhages.
■ Leukocyte cylinders are observed quite rarely, almost exclusively with pyelonephritis.
■ Cylinders are mucus filaments originating from collecting tubes. Often appear in the urine at the end of the nephritic process, do not have diagnostic value.
Salts and other elements. The precipitation of salts depends mainly on the properties of urine, in particular on its pH.Urinary and hippuric acid, mono-acid salts, calcium phosphate, calcium sulphate drop out in urine, which has an acid reaction. Amorphous phosphates, triphyl phosphates, neutral magnesium phosphate, calcium carbonate, sulfonamide crystals are precipitated in urine that has an alkaline reaction.
■ Uric acid. Uric acid crystals are normally absent. Early( within 1 h after urination) precipitation of uric acid crystals in the sediment indicates a pathologically acidic pH of the urine, which is observed in renal failure. Uric acid crystals are found in fever, conditions accompanied by increased decay of tissues( leukemia, massive decaying tumors, resolved pneumonia), as well as with severe physical exertion, urine acid diathesis, consumption of exclusively meat food. With gout, a significant loss of uric acid crystals in the urine is not noted.
■ Amorphous urates - urate salts, impart urine sediment to brick-but-pink color. Amorphous urates are normally single in the field of view. In large quantities, they appear in the urine with acute and chronic glomerulonephritis, CRF, congestive kidney, febrile states.
■ Oxalates are oxalic acid salts, mainly calcium oxalate. Normally, oxalates are single in the field of vision. In a significant number of
ve they are found in urine with pyelonephritis, diabetes, calcium metabolism, after an attack of epilepsy, when eating large amounts of fruits and vegetables.
■ Tripolyphosphates, neutral phosphates, calcium carbonate are normally absent. Appear with cystitis, copious intake of plant foods, mineral water, vomiting. These salts can cause the formation of concrements - more often in the kidneys, less often in the bladder.
■ Acid ammonium urate is normally absent. Appears in cystitis with ammonia fermentation in the bladder;in newborns and infants in neutral or sour urine;uric acid infarction of the kidneys in newborns.
■ Cystine crystals are normally absent;appear with cystinosis( congenital impairment of amino acid metabolism).
■ Leucine, tyrosine crystals are normally absent;appear with acute yellow dystrophy of the liver, leukemia, smallpox, poisoning with phosphorus.
■ Chrysotile crystals are normally absent;they are found in amyloid and lipoid dystrophy of the kidneys, echinococcosis of the urinary tract, neoplasms, abscess of the kidneys.
■ Fatty acids are not normally present;they are rarely detected with fatty degeneration, decay of the epithelium of the renal tubules.
■ Hemosiderin( Hb degradation product) is normally absent, appears in the urine with hemolytic anemia with intravascular hemolysis.
■ Hematoidin( Hb-free iron-free decomposition product) is normally absent, appears with calculous pyelitis, kidney abscess, neoplasms of the bladder and kidneys.
Bacteria are normally absent or their number does not exceed 2х103 in 1 ml. Bacteriuria is not absolutely reliable evidence of an inflammatory process in the urinary system. The content of microorganisms is of decisive importance. The presence in 1 ml of adult urine of 105 microbial bodies and more can be regarded as an indirect sign of the inflammatory process in the urinary organs. Determination of the number of microbial bodies is carried out in the bacteriological laboratory, in the study of the general analysis of urine, only the very fact of the presence of bacteriuria
Yeast fungi are normally absent;they are found in the presence of glucose, antibiotic therapy, prolonged storage of urine.
Protozoa are normally absent;quite often in the study of urine detect Trichomonas vaginalis.