1 / 60

Clinical Urinalysis Review

Clinical Urinalysis Review. Austin Community College Medical Laboratory Technology Clinical II Spring 07. Urine Blood Testing. http://library.med.utah.edu/WebPath/TUTORIAL/URINE/URINE.html. Chemical Exam of Urine. Chemical Exam of Urine. Chemical Exam of Urine. Reagent strip manufactures

etta
Download Presentation

Clinical Urinalysis Review

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Clinical Urinalysis Review Austin Community College Medical Laboratory Technology Clinical II Spring 07

  2. Urine Blood Testing • http://library.med.utah.edu/WebPath/TUTORIAL/URINE/URINE.html

  3. Chemical Exam of Urine

  4. Chemical Exam of Urine

  5. Chemical Exam of Urine • Reagent strip manufactures • Bayer Corporation- Diagnostics Division (formerly Ames) produces Multistix • Boehringer-Mannheim Corporation which produces Chemstrip • Behring Diagnostics which produces Rapignost

  6. Chemical Exam of Urine

  7. Chemical Exam of Urine • Reagent strip precautions and source of errors • Normal dipstick procedure: • Dip strip briefly, but completely into well mixed, room temperature urine sample. • Withdraw strip, blot briefly on its side • Keeping the strip flat, read results at the appropriate times by comparing the color to the appropriate color on the chart provided.

  8. Chemical Exam of Urine • Sources of error (& preventions) • Testing cold specimens • would result in a slowing down of reactions; test specimens when fresh or bring them to RT before testing • Inadequate mixing of specimen • could result in false reduced or negative reactions to blood and leukocyte tests; mix specimens well before dipping • Over-dipping of reagent strip • will result in leaching of reagents out of pads; briefly, but completely dip the reagent strip into the urine

  9. Chemical Exam of Urine • Inadequate blotting & Failure to keep strip horizontal • will result in over-run or mixing of reagents between the different reaction pads; blot excess urine off the strip and keep strip horizontal. If dipping from the tube, can run the side of the strip along the rim to remove excess urine. • Improper timing of tests • over development of reagent pad colors leading to falsely increased results; follow manufacturer’s recommendations

  10. Chemical Exam of Urine • Inadequate light • misinterpretation of results; use good lighting • Mis-using color chart • misinterpretation of results; hold strip just over color chart and match colors as close as possible, consider use of back-up tests, if needed, especially if urine’s color masks reaction colors.

  11. Chemical Exam of Urine • Handling and Storage • Keep strips in original container, stored at RT • Protect from moisture and volatile fumes • Use before expiration date • Do not touch reagent pad areas

  12. Chemical Exam of Urine • Quality Control - use appropriate, commercially prepared positive and negative controls. • Use commercially prepared pos and neg controls, at least once per 24 hours, and anytime a new bottle is opened, or question of validity of results. Readings should agree with published results ± one color block.

  13. Urine Glucose Testing • Normal : no glucose detected • Clinical significance of abnormal results (Glucosuria) • Plasma glucose level exceeds renal threshold (160-189 mg/dL) • Diabetes mellitus • Renal tubular dysfunction • Filtered glucose not being reabsorbed in tubules

  14. Urine Glucose Testing • Dipstick Testing Method • Glucose initiates reaction • Coupled reaction • Glucose oxidase – oxidizes glucose to gluconic acid and concurrently reduces oxygen to hydrogen peroxide. • Hydrogen peroxide in presence of the enzyme peroxidase will oxidize an indicator, giving a colored reaction. • Chromogens • Potassium iodide or • Tetramethylbenzindine

  15. Urine Glucose Testing • Sensitivity • @ 50-100 mg (compared to Clinitest’s 250) SO- Can have a positive dipstick but a neg Clinitest • Specificity - is specific for glucose only. • not affected by other sugars or reducing substances.

  16. Urine Glucose Testing • Interfering substances • High specific gravity and high pH may depress color. • Ascorbic acid-false neg • Bleach or peroxide may give false positive

  17. Urine Bilirubin Testing • Normal : no bilirubin detected • Clinical significance of abnormal results (Bilirubinuria) • Jaundice - Condition when serum bilirubin becomes greater than the liver can handle, and there is an abnormal collection of bilirubin in the tissues giving them a yellow color

  18. Urine Bilirubin Testing • Prehepatic / Hemolytic jaundice • Excessive hemolysis of RBC; beyond what the liver can process • Type of bilirubin? • Is bilirubin found in the urine? YES/NO? Explain.

  19. Urine Bilirubin Testing • Prehepatic / Hemolytic jaundice • Type of bilirubin? – indirect, insoluble, unconjugated • Is bilirubin found in the urine? – No, the bilirubin is not water soluble

  20. Urine Bilirubin Testing • Hepatic jaundice • Liver’s cells malfunctioning • Ie. viral hepatitis, cirrhosis etc. • Both (direct) bilirubin and urobilinogen found in urine.

  21. Urine Bilirubin Testing • Post hepatic (regurgative or obstructive) hepatitis • Obstruction to outflow of bile – some type of blockage • Gall stones • Tumor • Edema • Conjugated bilirubin backed up into blood (Bilirubinuria) and passes into urine

  22. Urine Bilirubin Testing • Testing method • Urine dipsticks for bilirubin – a diazo reaction • Impregnated with stabilized diazotized 2,4 dichloraniline • Color goes from buff to brown also shades of pink – violet • If urine is strongly colored, look for change in pad color after dipping. Use Ictotest for backup.

  23. Urine Bilirubin Testing • Interfering substances • Medication metabolites, pigments and indican may obscure readings • False negatives due to aged specimens, especially those exposed to light and oxidation.

  24. Urine Ketone Testing • Ketone Bodies • Origin - not normally present • Products of fat catabolism - breakdown of fat into CO2 and H2O • What are the 3 ketone bodies?

  25. Urine Ketone Testing • Acetone • 2%. -Acetone is volatile, & excreted primarily through the lungs • Diacetic Acid (Acetoacetic) • the first formed, • 20 % of the total • the form detected by most ketone test procedures • Beta hydroxybutyric Acid • majority formed, but not detected by routine tests. • Only Hart’s test, an old ‘wet chemical’ test will detect this one.

  26. Urine Ketone Testing • Definitions • Ketonuria - ketones in the urine • Ketonemia - ketones in the blood • Ketosis - disease state, when patient has increased amount of ketones. • Acidosis - state when blood pH is decreased, an accumulation of acids; commonly occurs as a result of ketosis

  27. Urine Ketone Testing • Clinical significance • Health – formed in liver and completely metabolized • Disease – excessive formation and accumulation • Disturbance of carbohydrate metabolism • when there is a decrease of carbohydrate metabolism, then the body stores of fat must be metabolized to supply energy. • As a result of this increased fat metabolism ketones will be found in the urine. Ex. low carbohydrate diets, diabetes • Starvation • Vomiting and diarrhea in children • Van Gierke's Disease – glycogen storage disease • High fat diet

  28. Urine Ketone Testing • Clinical effects • Metabolic acidosis • Lowering of blood & urine pH • Brain toxicity

  29. Urine Ketone Testing • Testing • most use nitroprusside • detects diacetic acid and a small amount of acetone, but does not detect β-hydroxybutyric acid. • Produces purple color • Can be used on urine or blood

  30. Urine Specific Gravity Testing • The specific gravity is a measure of the weight of urine compared to an equal amount of water.  • Specific gravity it proportional to urine osmolality which is a measure of concentration.

  31. Urine Specific Gravity Testing • The specific gravity will always be greater than 1.000 and will increase as more materials are dissolved in the urine.  • The value changes throughout the day depending on fluid intake.

  32. Urine Specific Gravity Testing • Specific gravity between 1.002 & 1.035 on a random sample is normal if kidney function is normal. • Specific gravity in Bowman’s capsule fluid is @ 1.007 • Any reading below this indicates hydration • Any reading above this indicates some degree of dehydration

  33. Urine Specific Gravity Testing • Again dilute urine will have values less than 1.010.  • Fixed specific gravity = 1.010; isothenuria • Diabetes insipidus • End-stage renal disease • And concentrated urine will have values usually over 1.020. • Usually due to dehydration and can be seen in well population as well as sick.

  34. Urine Specific Gravity Testing • Increased urine specific gravity may indicate / be seen in: • * Dehydration • * Diarrhea • * Excessive sweating • * Glucosuria • * Heart failure (related to decreased blood flow to the kidneys) • * Renal arterial stenosis • * Syndrome of inappropriate antidiuretic hormone secretion (SIADH) • * Vomiting • * Water restriction

  35. Urine Specific Gravity Testing • Decreased urine specific gravity may indicate / be seen in: • * Excessive fluid intake • * Diabetes insipidus – central or nephrogenic • * Renal failure (that is, loss of ability to reabsorb water) • * Pyelonephritis

  36. Urine Specific Gravity Testing • Specific gravity > 1.035 (refractometer) • Could have very high glucose levels • Could contain radiographic dye

  37. Urine Specific Gravity Testing • Testing • Polyelectrolytes , pH indicator (bromthymol blue measures the pH change), and alkaline buffer

  38. Urine Specific Gravity Testing • Interfering substances • False elevation of results may be seen in samples with increased protein concentration. • Some reports of reduced specific gravity results on alkaline specimens. • Lipids may also effect results

  39. Urine Blood Testing • Normally not found in urine • Hemoglobinuria – free hemoglobin in urine • Circulating free hemoglobin normally picked up by haptoglobin preventing loss in urine • When serum levels of hemoglobin > 100 mg/dL threshold is exceeded • Hematuria – RBCs in the urine • Trauma / irritation of renal organs

  40. Urine Blood Testing

  41. Urine Blood Testing • Testing dipstick reaction

  42. Urine Blood Testing • ‘Blood’ test detects • Free Hemoglobin • RBCs – get lysed on the pad & their hemoglobin reacts • Myoglobin – muscle hemoglobin • Principle based on the peroxidase-like activity of the heme portion of the molecule

  43. Urine Blood Testing • Sensitivity – can detect at levels of 5-10 cells/uL • Interfering substances • Ascorbic acid • Nitrates • Oxidizing agents (ie bleach) • Contaminate blood (menstrual)

  44. Urine pH Testing • Normal: kidneys capable of 4.5 – 8.0 • Factors effecting pH • Diet – general & specific foods • Time of day • Metabolic disorders • Drugs / medications • Dipstick capable: 4.5 – 9.0

  45. Urine pH Testing • Test method • Dipstick indicators – methyl red and bromthymol blue • Range 4.5-9.0 • Caution – other chemicals on dipstick can effect pH reading

  46. Urine Protein Testing • Normally not found in measurable amounts on dipstick (<150 mg/dL /day) • Permeability of glomerulus • Damage to glom capularies • Changes in glom blood flow • Albumin excretions may be increased temporarily due to exercise, uti, and acute illness with fever. • Dipstick results of >@ 1+ (30mg/dL) would equal to @ 500 mg/dL (clinical proteinuria)

  47. Urine Protein Testing • Only albumin detectable by dipstick • Sensitivity (@15-30 ml/dL)

  48. Urine Protein Testing • New testing for microalbumin & creatinine • Results: • Protein 20-200 mg/dL (30-300 mg/dL /24 hr) • Creatinine 10-300 mg/dL • Albumin/creatinine ratio • Normally albumin in the urine is less than 30 mg/ gram creatinine

  49. Urine Protein Testing • Principle - Protein error of indicators • at fixed pH, certain indicators show one color in the presence of protein and another in absence of protein - the “error” of the indicator. • Indicator – tetrabromphenol blue - can be hard to read at the trace end • Citrate Buffer – maintains pH 3 -quite acid

  50. Urine Protein Testing • Sources of error • Sensitive only to albumin • Urine with strong / unusual color makes reading difficult • Highly alkaline or buffered urine will neutralize acid buffer and lead to increased erroneous results. • Urine container contamination would interfere

More Related