Diagnostic Indications Of Urinalysis PDF

DIAGNOSTIC INDICATIONS OF Urinalysis Dr S.b. bani  DIAGNOSTIC INDICATIONS OF URINE CHEMISTRY TESTS Macroscopic examination ü Colour ü Appearance The common chemical testing of urine utilizes commercial disposable test strips. E.G. Multistix 10 SG /COMBI-10 test strips test for 1....

DIAGNOSTIC INDICATIONS OF Urinalysis Dr S.b. bani  DIAGNOSTIC INDICATIONS OF URINE CHEMISTRY TESTS Macroscopic examination ü Colour ü Appearance The common chemical testing of urine utilizes commercial disposable test strips. E.G. Multistix 10 SG /COMBI-10 test strips test for 1. Glucose 2. Bilirubin 3. Ketone 4. Specific Gravity 5. Blood 6. pH 7. Protein 8. Urobilinogen 9. Nitrite and 10. Leukocyte Esterase The result of this testing is regarded as semiquantitative.  DIAGNOSTIC INDICATIONS OF URINE CHEMISTRY TESTS 1. A fresh urine specimen is collected in a clean, dry container. 2. A Multistix strip is briefly immersed in the urine specimen, covering all reagent areas. 3. The edge of the Multistix strip is run against the rim of the urine container to remove excess urine. 4. The strip is held in a horizontal position. 5. The reactions are read visually or automatically with a Clinitek reflection photometer. 6. If the strip is evaluated visually, the strip test areas are compared to those on the Multistix color chart at the specified times. 7. The results are recorded, and the strip is discarded.  DIAGNOSTIC INDICATIONS OF URINE CHEMISTRY TESTS diagnostic – method used to find out what physical or mental problem PRESENT/someone has. Indication – a sign that something will happen is true or exists. Diagnostic indication – finding out what condition someone has/ does not have based on the results of a test (urine chemistry). Renal Structure and Functions  Renal Structure and Functions Kidney (nephron and tubules) ü Regulates the volume of body fluids ü Regulates the composition of body fluids ü Maintains homeostasis Ureter ü Links the kidney to the bladder Bladder ü Storehouse for urine Urethra ü Links the bladder to outside the body In diseased conditions ü Substances normally reabsorbed or excreted in small amounts by the kidneys may appear in the urine in large amounts ü Substances normally excreted may be reabsorbed  What is urine? Ø It is a waste product of the body composed of about 95% water electrolytes (sodium, potassium, magnesium, chloride, bicarbonates), and the waste products of metabolism (urea, uric acid, and creatinine) The production and composition of urine depends on glomerular filtration, tubular reabsorption and tubular secretions  Urinalysis üan array of tests performed on urine (chemistry and microscopy) to determine the nature, causes and prognosis of diseases. Applications üRoutine medical examinations üScreening and preventive medicine üMonitoring diseases and its therapy  urine chemistry strip tests Standard urine chemistry strip 1. specific gravity 2. pH 3. Nitrite 4. leucocytes 5. Protein 6. Blood 7. Glucose 8. ketones 9. Bilirubin 10. urobilinogen  Specific Gravity Principle based on the apparent pKa change of certain pretreated polyelectrolytes, poly(methyl-vinyl-ether/maleic anhydride), in relation to ionic concentration. ü In the presence of bromthymol blue, colors range deep blue-green in urine of low ionic concentration through green and yellow-green in urines of increasing ionic concentration. The sg is a convenient index of urine concentration. ü It measures density and is an approximate guide to true concentration. ü A sg of 1.025, in the absence of protein, glucose and other large molecular weight substances such as contrast media, usually indicates normal renal concentration and makes chronic renal insufficiency unlikely. Preferable Sample ü First morning urine or one that has remained in the bladder for at least 4 hours. Specific Gravity ü Compares the density of urine to the density of water. ü Indicates the relative proportions of dissolved solid components (solutes) in the total volume of the specimen (1.003 – 1.030). ü Indicates the hydrated status of the patient. The more solutes (eg urea, sodium, glucose etc) present, the higher the mass density and therefore the specific gravity will be. ü useful when assessing degree of proteinuria, glucosuria, haematuria etc. Low ü Inability of the kidney to concentrate urine (1.001 – 1.003) ü Results from renal abnormalities such as nephritis and diabetes insipidus High ü Results from excessive loss of water, hepatic diseases, cardiac diseases, shock, nephrotic syndrome etc ü Can increase as high as 1.050 in diabetes mellitus or nephrosis due to particularly glucose and  pH Principle ü The test is based on the double indicator (methyl red/bromthymol blue) principle that gives a broad range of colors covering the entire urinary pH range. Colors range from orange through yellow and green to blue.  pH ü variations in ph occur with the presence of excess acidic or basic compounds in the urine. When there is proximal tubule dysfunction, the tubules fail to secrete hydrogen ions and fail to reabsorb bicarbonate normally. ü In distal tubular dysfunctions, the tubules are usually unable to secrete hydrogen ions and also cause an elevation in the urine pH. ü Phosphates will precipitate in an alkaline urine, and uric acid will precipitate in an acidic urine, depending on the availability of these substances.  Urine pH ü Normal freshly passed urine is slightly acidic ü ph – 6.0 but can range from 4.5-8.0 Depends on ü acid base balance ü water balance ü Diet ü Renal tubular function important screening test for the diagnosis of 1. renal disease, 2. respiratory disease, and 3. certain metabolic disorders that come with acid-base disorders. High ph ü severe vomiting (lose H+), ü asthma, kidney diseases ü Kidney stones (calcium- and phosphate-containing stones, whereas acidic urine pH promotes uric acid or cystine stones ü bacteria infection in some utis  URINE pH Low ph ü severe diarrhea ü severe lung diseases ü uncontrolled diabetes ü Starvation ü too much alcohol ü High meat diet ü Insulin insufficiency False reactions Prolonged exposure of unpreserved urine results in microbial proliferation with resultant changes in ph ü Urea is converted to ammonia ü false positive protein results ü glucose is metabolized by organisms (BACTERIA ETC) ü Urine becomes more alkaline because of the loss of co2, and the conversion of urea to ammonia  pH ü Fanconi syndrome is a rare disorder of kidney tubule function that results in excess amounts of glucose, bicarbonate, phosphates (phosphorus salts), uric acid, potassium, and certain amino acids being excreted in the urine.  pH PRINCIPLE This test depends upon the conversion of nitrate (derived from the diet) to nitrite by the action of Gram negative bacteria in the urine. nitrite in the urine reacts with para-. arsanilic acid to form a diazonium compound. This diazonium compound in turn couples with 1,2,3,4- tetrahydrobenzo(h)quinoline-3-ol to produce a pink color.  Nitrite/wbc ü Indicate increased catabolism of proteins in the body following a high-protein meal or a urinary tract infection. ü Bacteriuria caused by some Gram negative bacteria which produce nitrate reductase enzyme & give a positive test. False reactions ü non – nitrate reducing bacteria (BACTERIA PRESENT BUT THE RXN MAY BE NEGATIVE) ü urine too short in bladder or not fresh ü urine with insufficient nitrate ü sensitivity reduces with high Specific gravity.  Proteinuria ü Undetected amounts are normal in certain individuals. ü up to 150mg/24hr or 10 mg/dl may be detected during strenuous exercise or dehydration. ü Indicates abnormally increased permeability of glomerulus due to renal infection or diseases that have secondarily affected the kidney eg. ü Diabetes mellitus ü jaundice ü hyperthyroidism  Proteinuria ü febrile illnesses ü severe UTI, eclampsia ü nephrotic syndrome (>3.0 – 3.5g/day) ü Schistosomiasis ü toxaemia in pregnancy (PREECLAMSIA): A condition in characterized by abrupt hypertension, and damage to one or more organs, often the kidneys (causing protein in the urine). albuminuria and edema of the hands, feet, and face. False positive reactions – urine contaminated with disinfectants containing quaternary ammonium compounds, strongly alkaline urine  PRINCIPLE Haematuria / haemoglobinuria The reagent is 3,3’,5,5’,tetramethylbenzidine (TMB) and di- isopropylbenzene dihydroperoxide. This reagent turns green in the presence of blood.  Haematuria / haemoglobinuria Schistosomiasis bacterial infections acute glomerulonephritis kidney stones sickle cell disease calculi malignancy haemolysis incompatible transfusion snake bite typhoid fever G6PD False reactions contaminating oxidizing agents (bleach, delayed examination, bacterial growth  Glucosuria principle This test is based on a double sequential enzyme reaction. One enzyme, glucose oxidase, catalyzes the formation of gluconic acid and hydrogen peroxide from the oxidation of glucose. A second enzyme, peroxidase, catalyzes the reaction of hydrogen peroxide with a potassium iodide chromogen to oxidize the chromogen to colors ranging from green to brown.  Glucosuria ü Results when the renal threshold for glucose (9 -10 mmol/l) is exceeded. ü indicates that the filtered load of glucose exceeds the maximal tubular re-absorptive capacity for glucose. Indicated in ü uncontrolled/untreated diabetes, ü in tubular damage ü pregnancy ü CNS disorders (DIABETIC NEUROPATHY) ü haemorrhage False reactions ü long standing bacteria contaminated urine give false rxn bcos of bacterial utilization of glu in urine  Ketone bodies (acetoacetate, beta- hydroxybutyrate, acetone) Metabolism of fat in the presence of insufficient insulin action or absence of glucose. involves hydrolysis of triglycerides to fatty acids and glycerol hydrolysis of fatty acids to smaller intermediate compounds (ketone bodies) and the utilization of these intermediate compounds in aerobic respiration. ü Untreated diabetes ü Starvation ü severe dehydration ü glycogen storage disease ü low carbohydrate diet ü alcoholism  Ketone bodies This test is based on the development of colors ranging from buff- pink, for a negative reading, to purple when acetoacetic acid reacts with nitroprusside. Urine testing only detects acetoacetic acid, not the other ketones, acetone or beta-hydroxybuteric acid. In ketoacidosis, with xtic fruit breath (insulin deficiency or starvation), it can be present in large amounts in the urine before any elevation in plasma levels principle Bilirubinuria ü This test is based on the coupling of bilirubin with diazotized dichloroanaline in a strongly acid medium. The color ranges through various shades of tan. ü The haem group of destroyed old RBC’s is converted to bilirubin, secreted into the blood and carried to the liver for conjugation. ü increased level of RBC destruction ü obstructive jaundice ü hepatocellular jaundice ü obstruction of common bile duct  Bilirubinuria ü Of value in the differential diagnosis of jaundice since bilirubinuria is not found with haemolytic jaundice and conditions associated with unconjugated bilirubin ü Bilirubin in the urine indicates the presence of liver disease or biliary obstruction. ü Very low amounts of bilirubin can be detected in the urine, even when serum levels are below the clinical detection of jaundice. False reaction – photosensitive, drugs  Urobilinogen Principle This test is based on the modified Ehrlich reaction, in which para-diethylaminobenzaldehyde in conjunction with a color enhancer reacts with urobilinogen in a strongly acid medium to produce a pink-red color. Urine urobilinogen is increased in any condition that causes an increase in production or retention of bilirubin.  Urobilinogen ü Excessive haemolysis leads to increased formation of bilirubin. Urobilinogen is then formed from bilirubin by bacteria in the large intestine. ü Levels depend on the ability of the liver to excrete that coming from the intestine Abnormally high levels ü hemolytic diseases ü enterocolitis ü hepatocellular damage ü dehydration ü fever Abnormally low levels ü obstruction of bile duct, ü absence or reduction in intestinal flora Negative reactions ü nitrite containing samples, ü intensive antibacteria therapy  leukocytes Granulocytic leukocytes contain esterases that catalyze the hydrolysis of the derivatized pyrrole amino acid ester to liberate 3-hydroxy-5-phenyl pyrrole. This pyrrole then reacts with a diazonium salt to produce a purple product. A positive leukocyte esterase test provides indirect evidence for the presence of bacteriuria.  MICROSCOPIC EXAMINATION Note that in many laboratories it is a standard practice to include the microscopic examination even if all chemical testing yields negative or normal results. In urinalysis microscopic exam one looks for formed ü cellular elements ü casts ü bacteria ü yeast ü parasites ü crystals in centrifuged urine sediment.  MICROSCOPIC EXAMINATION ü PROCEDURE Centrifuge 5.0 mL of a mixed, freshly voided or catheterized urine in a conical centrifuge tube for 5 minutes at high speed. ü Remove 4.9 mL (or 90% of whatever volume was centrifuged) of the supernatant fluid, leaving a 10-fold concentration of the urine as sediment. ü Resuspend the sediment by gently mixing with a vortex mixer. Place a drop of stained or unstained suspension on a microscope slide and coverslip ü allow the slide to stand for 2 minutes, so that most elements will settle. Place the slide on the microscope stage.  MICROSCOPIC EXAMINATION ü PROCEDURE Examine several fields at X10 magnification for casts. Classify and count the number of casts and report as a least-to-most range (eg. 5-10) for each type seen within LPF (Low Power Fields). ü Switch to X40 magnification and examine for other elements, i.e., WBCs, RBCs, Epithelial cells, yeast, bacteria, Trichomonas vaginalis, Sperm cells, mucous filaments and crystals. ü Again, classify and report each element by a least-to-most, range per HPF (High Power Field). Yeast, bacteria, mucous filaments and crystals are usually graded using the '+' notation (1+ = least significant amount, 4+ = most significant amount). ü Occasionally, the fields are packed with cellular elements or casts, so that it is impractical to count their numbers; in this case use the notation 'TNTC' (Too Numerous To Count/many). Hyaline cast  Hyaline casts ü Hyaline casts are formed in the absence of cells in the renal tubular lumen. ü They have a smooth texture and a refractive index very close to that of the surrounding fluid. ü When present in lower numbers (0-1/LPF) in concentrated urine of otherwise normal patients, hyaline casts are not always indicative of clinically significant disease. ü Greater numbers of hyaline casts may be seen associated with proteinuria of renal (eg., glomerular disease) or extra- renal (eg., overflow proteinuria as in myeloma) origin. Cellular casts  Cellular casts ü most commonly result when disease processes such as ischemia, infarction or nephrotoxicity cause degeneration and necrosis of tubular epithelial cells. ü A common scenario is the patient with decreased renal perfusion and oliguria secondary to severe dehydration. ü ü Ischemic injury results in degeneration and sloughing of the epithelial cells. The resulting casts often are prominent in urine produced following rehydration with fluid therapy. ü The restoration of urine flow flushes numerous casts out of the tubules. ü Leukocytes can also be incorporated into casts in cases of tubulo-interstitial inflammation (eg., pyelonephritis). ü Budding yeast cells and mucous filaments are a common feature of cellular casts.  Granular casts ü Granular casts have a textured appearance which ranges from fine to coarse. ü Since they usually form as a stage in the degeneration of cellular casts, the interpretation is similar to that for cellular casts. ü Sperm cells are also present in the photomicrograph below. Granular casts  Fatty casts ü identified by the presence of refractile lipid droplets. ü The background matrix of the cast may be hyaline or granular. Often, they are seen in urines in which free lipid droplets are present as well. ü Interpretation of the significance of fatty casts should be based on the character of the cast matrix, rather than on the lipid content. ü Pictured is a fatty cast with a hyaline matrix. As an isolated finding, lipiduria is seldom of clinical significance. Fatty casts  Waxy casts ü Waxy casts have a smooth consistency but are more refractile and therefore easier to see compared to hyaline casts. They commonly have squared off ends, as if brittle and easily broken. Waxy casts are found especially in chronic renal diseases, and are associated with chronic renal failure ü they occur in diabetic nephropathy, malignant hypertension and glomerulonephritis. waxy casts  Oval Fat Bodies (OFB) ü similar in composition and significance to fatty casts. ü "Dysmorphic" red cells refer to heterogeneous sizes, hypochromia, distorted irregular outlines and frequently small blobs extruding from the cell membrane. ü Desmorphic red cells (picture observed in glomerulonephritis.  White Blood Cells ü WBC in unstained urine sediments typically appear as ü Round, granular cells which are ü 1.5-2.0 times the diameter of RBCs. ü WBC in urine are most commonly neutrophils. ü Like erythrocytes, WBC may lyse in very dilute or highly alkaline urine; ü WBC cytoplasmic granules released into the urine often resemble cocci bacteria. ü WBC up to 5/HPF are commonly accepted as normal. ü Greater numbers (pyuria) generally indicate the presence of an inflammatory process somewhere along the course of the urinary tract (or urogenital tract in voided specimens). ü Pyuria often is caused by urinary tract infections, and often significant bacteria can be seen on sediment preps, indicating a need for bacterial culture.  RBC ü Fresh RBC tend to have a red or yellow color. Prolonged exposure results in a pale or colorless appearance as hemoglobin may be lost from the cells. ü In fresh specimens with a Specific Gravity (SG) of 1.010-1.020, RBC may retain the normal disc shape. In more concentrated urines (SG>1.025), RBC tend to shrink and appear as small, crenated cells. ü In more dilute specimens, they tend to swell. At a SG