Presentation on theme: "Interpretation of abnormalities in urine"— Presentation transcript:
1Interpretation of abnormalities in urine Shiva SeyrafianIsfahan University of Medical Sciences20/8/ /10/2012
2The aim of this lecture Urine tests (GFR and Proteinuria) Urinalysis and urine sediment
3What you should learn at the end of this lecture To know what are the urine tests.How do we measure urine tests?What is urinalysis?How do we exam urinalysis?What is the benefit of learning urine tests and urinalysis?
4Tests of Glomerular Filtration Rate Creatinine ClearanceNormal finding : male : ml/ min female : ml /min
5Calculation of creatinine clearance 24 hour urine collectionC cr = U cr x V/ P cr2- Cockroft- Gault FormulaC cr = (140 – age in years) x ( lean body weight in Kg) / S cr x 72For women multiply final value by 0.85 OR put 85 instead of 72.3- Modification of Diet in Renal Disease FormulaGFR = 186 X (Cr) x age x [0.742 (if woman)]Normal range = ml/min/ 1.73 m2
7Tests that predict kidney disease Albumin/ Creatinine Ratio (ACR or Microalbumin)
8Albumin Creatinine Ratio (Microalbumin) In health, there is very little or no albumin in the urineMost dip sticks report albumin at greater than 150 mg/LNormal microalbumin: mg/24hrs
9Urinary Albumin – cont’d Detection of low levels of albumin (even if below dipstick cut-off) is predictive of future kidney disease with diabetesVery significant variation usually requires repeat collectionsMicroalbuminuria: DM, Hypertension and early GN
10Urinalysis The most commonly performed As a screening procedure for asymptomatic individual.To confirm the presence of renal disease, diabetes, or, more rarely, liver disease.can be performed in emergency rooms, outpatient clinics, private physicians' offices, and patients' homes.Routine examination of urine continues to be one of the most commonly performed clinical laboratory procedures, usually as a screening procedure for asymptomatic individual, to confirm the clinical impression of the presence of renal disease, diabetes, or, more rarely, liver disease.can be performed in a variety of clinical settings, including emergency rooms, outpatient clinics, private physicians' offices, and patients' homes.
11UrinalysisThree types of urinalysis can be performed: 1-dipstick urinalysis, 2- microscopic urinalysis, 3-cytodiagnostic urinalysis (specialized analyses) ,2= routine urinalysisCytodiagnostic urinalysis is more time- consuming than traditional microscopic analysis
12Specimen Collection Midstream, catheterized, suprapubic aspiration Ideally within 30 minutes of collectionSpecimens > 2 hours old are inaccurateCan be refrigerated at 4oc up to 6 hoursAmorphous urate may precipitateShould return to room temperature
14Urinalysismacroscopic analyses consisting of physicochemical determinations (appearance, specific gravity), and multi-parameter reagent-strip measurements of biochemical constituents,microscopic examination of urinary sediment: hematuria, pyuria, cylindruria (casts), crystalluria, and others.
16Physical Examination of Urine physicochemical determinations Volume ( ml/ day)Odor (Mild, inoffensive odor)Appearance (color and turbidity)Many laboratories may also be equipped with refractometer that can relate density of a solution to specific gravity. Refractometers work on the principle that light passing from a transparent medium of one density to a medium of another density, will change its velocity and therefore the direction in which the beam of light is moving. This change in direction, or the bending, of light is called refraction. The refractivity of a solution is dependent, in great part, on the total mass of solids dissolved in that solution. The refractive index scale can be calibrated to measure the specific gravity of most urine sample, that is up to g/mLOsmolality is usually measured by an osmometer, most frequently by a freezing point osmometer. Osmolality is a measure of the number of particles per unit mass, whereas the specific gravity is a reflection of the density (mass per unit volume) of the suspended particles.
17Bad odor to the urine Either cystitis or vaginitis Look for: -Lost and forgotten tampon -Yeast -Trichomonas -Bacterial vaginosis -Asparagus eating -Ampicillin intake
22Physical Examination of Urine physicochemical determinations iv. Specific gravity: refractometer [measures the density (mass per unit volume) of the suspended particles]The normal range is to g/mL. A value of or greater indicates good renal function
25Physical Examination of Urine physicochemical determinations V. Osmolality: osmometer ( the number of particles per unit mass).The healthy kidney is capable of producing urine with a wide range of concentrations, from 50 to mOsm/kg. Normally, a urine's osmolality will range from approximately one-sixth to four times the osmolality of normal serum (280 to 290 mOsm/kg).
26Physical Examination of Urine Reagent-strip testing urine pH The urinary pH range is usually 4.7 to Extremely acidic or alkaline urine usually indicates a poorly collected specimen.More acidic with increased meat intakeMore alkaline with vegetarian dietHigh pH with prolonged storage or urea splitting organisms, diuretic therapy, vomiting, ,gastric suction and alkali therapy.
28Normally not detectable in the urine Chemical Examination of Urine Reagent-strip testing Blood and myoglobinNormally not detectable in the urineOxidizing agents such as povidone - iodine and myoglobin will cause a positive reactionPositive dipstick without RBCs suggests hemolysis or rhabdomyolysis.
29Chemical Examination of Urine Reagent-strip testing Bilirubin: no detectable in the urineUrobilinogen: 2-10 mg/LOnly conjugated bilirubin is passed into the urine.In hemolysis urine urobilinogen is often positiveFalse positive test for urine bilirubin can occur if the urine is contaminated with stoolProlonged storage and exposure to light can lead to false negative results.
30Chemical Examination of Urine Reagent-strip testing Sugars: not detectable sugars in the urine.Ketones: not detectable in the urineNitroprusside reaction used to detect ketones (acetone and acetoacetate)b-OH butyrate is not normally detected
31Chemical Examination of Urine Reagent-strip testing Nitrites: detect bacteriuria: measures the nitrite formed from converaion of nitrates to nitrites by certain bacteria in urine.Normally does not contain detectable nitrite.False negative:Ascorbic acid and high urine SGLow urinary nitrates (due to diet)Rapid transit of urine (takes 4 hrs to convert nitrates to nitrites in bladder )Degradation of nitrites (prolonged storage of urine)Gram positives, N. gonorrhea, M. TB.
32Chemical Examination of Urine Reagent-strip testing Leukocytes: pyuria (leukocytes in urine) are based on the presence of intracellular esterases released from lysed granulocytes, .Normally does not contain detectable leukocytes.False positiveLong standing urine, more granulocyte lysisVaginal contamination
33Normal Proteinuria 30 to 150 mg/day Usually only small proteins (<20,000 daltons) pass across capillary wall and most are reabsorbed in prox. tubules e.g., a2-microglobulin, apoproteins, enzymes, peptide hormonesTamm-Horsfall protein (uromodulin)High m. wt. 23 x 106 daltons glycoproteinThick ascending limb and distal convoluted tubuleIgA and urokinase in small amounts
34False Negative Results Bence Jones proteins Heavy-chain proteinsFalse Positive Result Alkaline urineSulfosalicylic acid:False negative Alkaline urine
38Chemical Examination of Urine – Microscopic examination of urine Red blood cell: Less than 3 erythrocytes per high- powered fieldWhite blood cell: Less than 5 leukocyte, per three high-power fields (400X) cells/mLTwice RBC size, cytoplasmic granulationInflammation or infectionEosinophils, best seen with Hansel’s stain or Wright’s stain
43Epithelial Cells Squamous, transitional, renal epithelial cells Squamous epithelial cellsLarge flat, 30 to 50 micrometers in diameterNucleus to cytoplasm size ratio is 1:6Contamination from distal genital tract
47CastsRenal casts are cylindrical structures that are formed in the nephron and excreted in the urine. Casts are significant because of their localizing value. Casts are composed of mucoprotein, or uromucoid, (Tamm- Horsfall protein), which is always present in urine, usually in solution.
48CastsThe Tamm- Horsfall mucoprotein is produced by the tubular epithelial cells lining the ascending limb of the loop of Henle.Casts are formed when urine stasis exists, which allows uromucoid to precipitate.Increased concentrations of protein and salts and a low urine pH all contribute to cast formation.
49CastsCasts: Less than 3 hyaline casts, zero to one granular cast, and no pathological cast per low-power field (100X).Casts include:RBCWBCEpithelialGranularHyalineFattyWaxy
60Crystals Least clinically important Crystals exist with/without presence of stonesCooling urine will have some crystal precipitateMore in concentrated urineCrystals: Small numbers of common, nonpathological crystals, such as uric acid or phosphate crystals.
61No specific disease,Present in Ca Ox stones and ethylene glycols toxicities
62No specific disease,Present in Ca Ox stones and ethylene glycol toxicities