Collection and Analysis

Collection of Specimen

In a clinical situation, depending upon diagnostic requirements, the conditions for specimen collection may be very precise. For example, one may need to collect all of the urine passed in a 24-hour period; or, it may be necessary to fast for some period before collection; or, it may be necessary to collect just one sample, e.g., 3 hours after a meal. The first morning sample may be discarded, or specifically collected for evaluation. A "midstream" sample may be required, the first few drops from micturation flush the urethra and carry information about the epithelium lining the urethra. the mid-stream sample is pure urine and provides information about the urine itself. The last few drops are not collected in the container.




For our purposes, you will need to collect enough sample to "float" the urinometer "float". You will also neet to measure the total "as collected" volume of your specimen for the required calculations, but you do not need to save more than the "float" volume for analytical work in the class lab.




One function of the kidney is to regulate your body fluid volumes. The largest fluid compartments are intracellular, interstitial, and blood. Blood Pressure (BP) correlates closely with blood volume. The greater the volume, the greater the pressure. Will the amount of fluid consumed by the subjecs affect BP?




1. Take your blood pressure before collecting your urine sample. __________ Record the data in the table.

   
   

2. Record the time of your last meal or snack. ________.

   
   

   What did you eat? _____ _____ _____ ____ ______ _____ ______ _____ _____ ____

   
   

   How long ago did you drink anything? _________. What did you drink? ____ _____ _____ ______ _____ ______

   
   

3. Collect your specimin in the plastic container provided. Determine the volume (vol) in ml from the graduations on the side. _____________ ml

   
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Appearance of Specimen

Urine color and odor is highly diet dependent.




Determine the visual appearance of your specimen. Normal color ranges from pale straw to amber. Carrots, beets, and rhubarb may alter the color, but this is nothing to worry about. Reddish, brownish, or greenish colors under other conditions are not normal. A very rare hereditary condition called alcaptanuria causes the urine to turn black when exposed to air.




A fresh sample of normal urine is usually clear but may become cloudy after standing. It may look cloudy right away if it contains fat from the last meal. Pus, bacteria, mucus, cells and certain salts can also cause cloudiness; microscopic examination may reveal the axact cause of cloudiness and determine whether it is abnormal.




Urine is normally odorless when freshly voided, although it takes on an ammonia odor after prolonged standing. Some people are unable to metabolize a certain substance found in asparagus, which imparts a characteristic odor. this is a harmless condition, but it does cause their urine to have a peculiar odor after a meal which included asparagus.




4. What is the color of your urine? __________________________

   
   

5. Is it transparent or cloudy? ___________________________

   
   

6. Is there any odor? ___________________________
   

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Specific Gravity

This is a measure of the relative proportion of water versus solutes in your sample. Pure water has a specific gravity (SG) of 1.000. A single urine specimen may have a S.G. as low as 1.002 (very watery) or as high as 1.040 (contains lots of solutes). When all of the urine for a 24 hour period is collected, consistently low or high S.G. may indicate diabetes, fever, or kidney disease.




7. Pour some of your urine into the urinometer container. then carefully insert the float, making sure that it does not stick to the sides. The instructor will demonstrate how to read the scale on the board. Ask for help if you have trouble reading the scale.

   
   

   What is the specific gravity of your specimen? ____________

   
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Estimation of Chloride

8. Measure 10 drops of urine into a test tube using a Pastuer Pipette. Add 1 drop of 20% K₂CrO₄ (potassium chromate). Then add 2.9% AgNO₃ (silver nitrate) one drop at a time while shaking continuously. Count the drops of silver nitrate required to turn the solution from bright yellow to brown. The total quantity of sodium chloride in the urine specime is they calculated as follows:

   
   

   NaCl (grams) = volume of entire specimen    X    drops of AgNO₃ added = _________
                                        1000

   
   

   (Where the volume of the entire specimen is the volume collected in 2.) Insert this value in the table for Cl.

   
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Chemical Tests

Hemoglobin in the urine is not normal. It indicates that either RBCs have been destroyed in large numbers in the body, or that blood has entered the urinary tract itself and RBCs have disintegrated in the urine. Hemoglobin in the urine thus may be a sign of hemolytic anemia, various diseases, burns, mushroom poisoning, kidney disease, or urinary tract infection.




Ketones result from the catabolism of fats. When such catabolism is increased beyond normal levels, then ketones "spill over" into the urine. this occurs in patients with diabetes and also in people following very-low-carbohydrate diets.




Glucose is normally "saved", resorbed, by the kidney and does not appear in the urine. However, in diabetes, when the patient lacks sufficient insulin to transfer glucose from the bloodstream into the body cells, the kidney is unable to resorb the total filtered glucose load. Therefore, the glomerulus filtrate contains glucose in excess to the levels that the kidney can resorb. The the excess glucose is excreted in the urine. In normal individuals, a very-high-carbohydrate meal will temporarily "overload" the bloodstream and the kidney may excrete some of the excess.




Protein molecules are too large to be filtered out of the blood into the urine. Disease states in which protein appears in the urine include kidney disease, certain diseases involving high fever, toxemia of pregnancy, and some anemias. In normal individuals, excessive muscular exertions, prolonged cold baths or swimming, and very-high-protein diets may put protein into the urine.




Acidity of a solution is measured by its pH: low pH, < 7 means acidity, 7 is neutral, and a pH > 7, up to 14, is basic or alkaline. Freshly voided urine is usually acid, with the normal range between 4.8 and 7.5. Persistent high acidity occurs in fevers, high-protein diets, and metabolic conditions which raise the body acidity in general. Persistent low acidity may mean urine retention in the bladder, urinary tract infections, anemias, and certain types of ulcers.




9. Dip a "Multi-Test" Lab-Stix into your initial specimen only and record the following values - You should just use pH paper for the later urine tests.

   
   

   Blood	_____________	Glucose	_____________	pH	__________
   Ketones	_____________	Protein	_____________	.	.

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Microscopic Examination

Normal urine will contain an accasional WBC, some epithelial cells, mucus, bacteria, and crystals of various kinds. An experienced technician can identify them and compare them to normal levels to determine whether any constituents are due to disease.



10. If you have extra time - Centrifuge a few cc's of your urine and examine the sediment under the microscope.