URINALYSIS (MLT 305) LECTURE ONE

1. URINALYSIS (MLT 305)LECTURE ONE Dr. Essam H. Jiffri

2. THE CHEMICAL EXAMINATION OF URINE • REAGENT STRIPS • - Reagent strips currently provide a simple, rapid means for performing 10 medically significant chemical analyses, including pH, protein, glucose, ketones, blood, bilirubin, urobilinogen, nitrite, specific gravity, and leukocytes.

3. THE CHEMICAL EXAMINATION OF URINE • - The two major types of dipsticks are manufactured under the trade names Multistix and Chemstrip. • - Reagent strips consist of chemical impregnated absorbent pads attached to a plastic strip. • - A color-producing chemical reaction takes place when the absorbent pad comes in contact with urine.

4. THE CHEMICAL EXAMINATION OF URINE • - Color reactions are interpreted by comparing the color produced on the pad with a chart supplied by the manufacturer. • - Several colors or intensities of a color for each substance being tested appear on the chart. • - By careful comparison of the colors on the chart and the strip, a semiquantitative value of trace, 1+, 2+, 3+, or 4 + can he reported.

5. THE CHEMICAL EXAMINATION OF URINE • REAGENT STRIP TECHNIQUE • - Testing methodology consists of dipping the strip briefly; into a well-mixed urine specimen; removing excess urine by touching the edge of the strip to the container as the strip is withdrawn; waiting the specified amount of time for the reaction to occur; and comparing the color of the strip with the color chart.

6. THE CHEMICAL EXAMINATION OF URINE • 1. Mix specimen well. • 2. Dip completely, but briefly, into specimen. • 3. Remove excess urine when withdrawing strip from specimen. • 4. Holding the strip horizontally Compare reaction colors with manufacturer's chart under a good light source at the specified time. • 5. The amount of time needed for reactions to take place varies between tests and manufacturers and ranges from an immediate reaction for pH to 120 seconds for leukocytes. • 6. Perform confirmatory tests when indicated. • 7. Be alert for the presence of interfering substances. • 8. Understand the principles and significance of the test. • 9. Relate chemical findings to each other and to the physical and microscopic urinalysis results.

7. THE CHEMICAL EXAMINATION OF URINE • Care of Reagent Strips • 1. Store with desiccant in an opaque, tightly closed container. • 2. Store in a cool place, but do not refrigerate. • 3. Do not expose to volatile fumes. • 4. Do not use past the expiration date. • 5. Use within 6 months after opening. • 6. Do not use if chemical pads become discolored.

8. THE CHEMICAL EXAMINATION OF URINE • Quality Control • 1. Test open bottles of reagent strips which known positive and negative controls during each laboratory shift. • 2. Resolve control results that are out of range by further testing. • 3. Test reagents used in confirmatory tests with positive and negative controls. • 4. Perform positive and negative controls on new reagents and newly opened bottles of reagent strips. • 5. Record all control results and reagent lot numbers.

9. THE CHEMICAL EXAMINATION OF URINE • AUTOMATION IN URINALYSIS • - Clini-Tek measures light reflected from a reagent strip that has been manually dipped in urine and inserted into the machine. • - Light reflection from the test pads decreases in proportion to the intensity of color produced by the concentration of the test substance. • - The instrument compares the amount of light reflection with that of known concentrations and displays or prints concentration units.

10. THE CHEMICAL EXAMINATION OF URINE • YELLOW IRIS • - The newest addition to automated urinalysis is the Yellow IRIS (International Remote Imaging), capable of performing specific gravity tests, routine chemical analysis, and a slideless microscopic analysis from an uncentrifuged specimen.

11. pH • The lungs, and the kidneys are the major regulators of the acid-base content in the body. • - A healthy individual will usually produce first morning specimen with a slightly acidic pH of 5.0 to 6.0, the pH of normal random samples can range from 4.5 to 8.0.

12. pH • Reagent Strip Reactions • - Both the Multistix and Chemstrip brands of reagent strips measure urine pH between pH 5 and 9. • - A double-indicator system of methyl red and bromthymol blue is used by both manufactures.

13. pH • CLINICAL SIGNIFICANCE OF URINE pH • 1. Respiratory or metabolic aciclosis • 2. Respiratory or metabolic alkalosis • 3. Defects in renal tubular secretion and reabsorption of acids and bases • 4. Precipitation of crystals and calculi formation • 5. Treatment of urinary tract infections • 6. Determination of unsatisfactory specimens

14. Protein • As a routine chemical tests performed on urine the most indicative of renal disease is the protein determination. • The presence of proteinuria is often associated with early renal disease. • Normal urine contains very little protein; usually, less than 10 mg/dl or 150 mg per 24 hours is excreted. • - This protein consists primarily of low-molecular-weight serum proteins that have been selectively filtered by the glomerulus, albumin is the major serum protein found in normal urine.

15. Protein • ORTHOSTATIC (POSTURAL) PROTEINURIA • - Benign proteinuria is usually transient and can be produced by conditions such as: • exposure to cold, • strenuous exercise, • high fever, dehydration, and • in the acute phase of sever illnesses. • - A more persistent benign protenuria occurs frequently in young adults and is termed orthostatic, or postural, proteinuria.

16. Protein • BENCE JONES PROTEIN • - In multiple myeloma, marked elevated levels of monoclonal immunoglobulin light chains ( Bence Jones protein). • Unlikeother proteins, which coagulate and remain coagulated when exposed to heat, Bence Jones protein coagulates at temperature between 400C and 600C and dissolve when the temperature reaches 1000C. • - The specimen that appears turbid between 400C and 600C and clear at 1000Ccan be suspected of containing Bence Jones protein.

17. Protein • CLINICAL SIGNIFICANCE OF URINE PROTEIN • 1.Glomerular membrane damage • a. Immune complex disorders • b. Amyloidosis • c. Toxic agents • 2. Impaired tubular reabsorption • 3. Multiple myeloma • 4. Orthostatic or postural proteinuria • 5. Preeclampsia • 6. Diabetic nephropathy

18. Glucose • - Glucose test is the most frequent chemical analysis performed on urine because of its value in the detection and monitoring of diabetes mellitus. • - Early diagnosis of diabetes mellitus through blood and urine glucose tests provides a greatly improved prognosis.

19. Glucose • REAGENT STRIP (GLUCOSE OXIDASE) REACTION • - Two very different tests are utilized by laboratories to measure urinary glucose, the glucose oxidase procedure provides a specific test for glucose. • 1. Glucose + O2 (air) glucose gluconic acid + H2O2 • oxidase • 2. H2O2 + chromogen Peroxidas oxidized chromogen + H20 • - Urine glucose may be reported in terms of trace, 1+, 2+, 3+ and 4+; however, the color charts also provide quantitative measurements ranging from 100 mg per dl to 2 g per dl, or 0.1 percent to 2 per­cent.

20. Glucose • COPPER REDUCTION TEST (Clinitest) • - The test relies on the ability of glucose and other substances to reduce copper sulfate to cuprous oxide in the presence of alkali and heat. • - A color change progressing from a negative blue through green, yellow, and orange to red occurs when the reaction takes place. • - The classic Benedict's solution was developed in 1908 and contained copper sulfate, sodium carbonate, and sodium citrate buffer.

21. Glucose • CLINICAL SIGNIFICANCE • - Under normal circumstances, almost all of the glucose filtered by the glomerulus is reabsorbed in the proximal convoluted tubule; therefore, urine contains only minute amounts of glucose. • - The blood level at which tubular reabsorption stops is termed the "renal threshold," which for glucose is between 60 and 180 mg per dl.

22. Glucose • SUMMARY OF CLINICAL SIGNIFICANCE OF URINE GLUCOSE • 1. Diabetes mellitus • 2. Impaired tubular reabsorption • a. Fanconi's syndrome • b. Advanced renal disease • 3. Central nervous system damage • 4. Pregnancy with possible latent diabetes mellitus

23. KETONES • - The term ketones represents; three intermediate products of fat metabolism, namely, acetone, acetoacetic acid,and beta-hydroxybutyric acid. • - Normally, measurable amounts of ketones do not appear in the urine, because all of the metabolized fat is completely broken down into carbon dioxide and water.

24. KETONES • REAGENT STRIP REACTIONS • The three ketone compounds are not present in equal amounts in urine, both acetone and beta-hydroxybutyric acid are produced from acetoacetic acid, and the proportions of 78 % beta-hydroxybutyric acid, 20 % acetoacetic acid and 2% acetone are relatively constant in all specimen.

25. KETONES • REAGENT STRIP REACTIONS • Reagent strip tests utilize the sodium nitroprusside (nitroferricyanide) reaction to measure ketones, in this reaction, acetoacetic acid in an alkaline medium will react with sodium nitroprusside to produce purple color. • - The test does not measure beta-hydroxybutyric acid and is only slightly sensitive to acetone.

26. KETONES • TUBE TESTS • The nitroprusside reaction is referred to as Rothera's test. • Tests to measure the individual ketones were also performed and included Gerhardt's test for acetoacetic acid and Hart's test for beta-hydroxybutyric acid. • - The removal of acetone and acetoacetic acid by boiling and the reaction of the remaining beta-hydroxybutyric acid with hydrogen peroxide constitute Hart's test.

27. KETONES • CLINICAL SIGNIFICANCE OF URINE KETONES • 1. Diabetic acidosis • 2. Insulin dosage monitoring • 3. Starvation