Introduction to Urinalysis Blast from the past!!! Hippocrates - 5th century BC wrote a book on “uroscopy” Middle ages - uroscopy has been a part of the physician’s training 1140 AD - color charts had been developed that described the significance of 20 different colors. 1694 - discovery of albuminuria by boiling urine. (Fredrik Dekkers) 1627 - Thomas Bryant published a book about the credibility of urinalysis that inspired the passing of the first medical licensure laws in England. 17th Century - Addis count was developed. (quantitation of microscopic sediments) 1827- Richard Bright introduced the concept of urinalysis as a part of routine patient examination.
Urine Volume Normal Urine volume 1200-1500 mL/ day
What is Urine? Aqueous solution of various organic and inorganic substances Substance may be either waste products resulting from body metabolism or products derived directly from the food eaten resulting from metabolism. • 97% water and 3% solids
Night Urine Not more than 400 mL Kidneys excretes 2-3 times in day than in night
Differentiation between DI & DM
Why Choose Urine for Analysis? 1. It is readily available and easily collected. 2. Contains information about the body’s major metabolic functions 3. Inexpensive laboratory testing can be performed. 4. It is most useful in ascertaining evidence of disease or disturbing function of the kidneys 5. Pathological lesion of the ureters, bladder or urethra 6. In male, lesion of the prostate and seminal vesicles. Urine Composition 1. Organic
Defective urine excretion (pathologic) 1. Defective hormonal regulation of volume homeostasis. 2. Defective renal salt/ water absorption. 3. Osmotic diuresis. Specimen Collection Clean, dry, leak-proof, disposable container 50 mL capacity (RECOMMENDED) Reject if there is no specimen label
2.
Inorganic
Specimen integrity Must be delivered and processed in the laboratory within 2 hours!! Urine Preservation
Low Temperature: Specimens are kept at cold temperature that would maintain all the natural components and characteristics of the sample undisturbed or unchanged. -
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Refrigeration – specimens are kept at cold temperature. This prevents the growth of bacteria and helps preserve the formed elements such as casts, red blood cells, white blood cell epithelial cells and an acidic pH. Dry ice or wet ice – Same action and preservation as refrigeration.
Chemical: This method of urine preservation will prevent: Conversion of urea to ammonium carbonate (alkaline, fermentation) by urea splitting organisms, particularly the Proteus group.) Destruction of glucose by yeasts or bacteria. False positive albumin test due to the presence of bacterial protein. Degeneration or destruction of organized sediments such as pus, blood, and casts.
5.
Sodium Fluoride or Benzoic Acid
6.
Phenol or Tricresol
CHEMICAL PRESERVATIVES
1.
Toluol (toluene)
2.
Amount Add a drop to an ounce of urine 0.5 ml for Addis count Use Specially used for Addis count (0.5 ml) Advantage Preserve urinary sediment quite well Disadvantage Prevents Obermayer test for indicant Reduces alkaline copper solution (Fehling and Clinitest) used for sugar test (false positive) Large quantity precipitate with urea that interferes with the microscopic examination
Thymol
4.
7.
8.
Amount 10 ml concentrated thorough mixing is requested before detection is performed Use Preserves 24 hours urine for the detection of ammonia, urea, total nitrogen and specially VMA Disadvantage Uric acid may be precipitated
Formaldehyde Tablets
9.
Amount A drop to an ounce of urine Use Often used in specimens forwarded to distant laboratories Advantage Can preserve specimen for some time An excellent preservative
HCl
Formalin (40%)
3.
Amount Add enough amounts to form a thin layer over the surface. (1-2 ml for steroids) May be skimmed off or the urine pipette from below it for use. Use Ideal preservative for steroids Advantage Does not interfere with tests Protects the urine from outside contamination Disadvantage Does not inhibit the growth of bacteria or mold spores that are already in the sample
Use Ideal for glucose analysis, such as glucose tolerance test (aid in regulating the insulin dosage) Advantage Prevents glycolysis
Amount One tablet is used for 2 ounces of urine Use Life insurance companies’ preservative Disadvantage Slightly increases the specific gravity
Sulfuric Acid
Amount Small crystal (about 5mm diameter) is added to 3 to 4 ounces of urine Advantage Good general preservative Disadvantage Excess amount may give a false positive albumin test May interfere with bile tests
Amount 1 ml concentrated Use Preserve cathecolamine, calcium, nitrogen and other inorganic constituents Changes in Unpreserved Urine
Chloroform
Amount Add a few drops at a time, until some of them remain at the bottom after mixing gently 10 ml for aldosterone Use Good preservative for aldosterone (10 ml) Advantage Produces a saturated solution set that it inhibits the growth of bacteria in the specimen Disadvantage Does not form a surface layer so it does not prevent contamination from the outside Interferes with sugar test (Fehling’s), since it reduces alkaline copper solutions Not an ideal preservative
Types of Urine Specimen Random specimen
Specimens collected anytime of the day
Most commonly received specimen in the laboratory. Useful for routine screening tests to detect obvious abnormality.
First Morning Specimen
First specimen voided. Most ideal specimen for screening/ testing Most concentrated specimen. Essential specimen for pregnancy test and orthostatic/ lordotic proteinuria.
Fasting Specimen (Second Morning Specimen)
Second voided specimen after a period of fasting. Best specimen for glucose monitoring.
Two Hour Post Prandial Specimen
Specimen collected after 2 hours of eating. Specimen used for monitoring insulin therapy in patients with DM. Glucose result from this specimen is compared with 2PPBS.
Glucose Tolerance Specimen
Specimen for used to check for the ability of the kidney to metabolize a measured amount of glucose. Correlated with renal threshold. side by side specimen with OGTT.
24- hour (Timed) Specimen
It is the total daily urine output. Used for quantitative urine testing. Begins and ends with an empty bladder If placed in 2 containers, mixed the urine samples well first before aliquoting To check for the completeness of 24 hour collection: Urine Creatinine determination 4-aminobenzoic acid (gold standard) Adult - 600-2000 mL/ 24 hours Less than 1 year old - 100-500 mL/ 24 hours 1 to 14 years old - 500-1400 mL/ 24 hours
Catheterized Sample
Most commonly requested for urine specimen for bacterial culture. Used to measure functions in the individual kidneys.
Midstream Clean-Catch Specimen
Safer, less traumatic specimen that is suitable for routine urinalysis and bacterial culture.
Suprapubic Aspiration
Collected directly from the urinary bladder. For bacterial bladder urine culture. Also used for cytologic examination.
Three- glass collection
Specimen used for the detection of prostatic infection. -
1st glass sample- first urine passed 2nd glass sample- midstream portion 3rd glass sample- prostate massage, remaining urine
Pediatric Specimen
Specimen collected from pediatric patients. Uses weebag, a soft, clear plastic bag with adhesive, for collection.
Drug Specimen
30-45 mL Urine temperature must be taken with 4 minutes from the time of collection. (32.5-37.7C) Collector adds bluing agent to the toilet water. Collector eliminates any source of water in the collecting area.
