Introduction to Urinalysis Flashcards
References to the study of urine can be found in the
Drawings of cavemen and in Egyptian hieroglyphics, such as the Edwin Smith Surgical Papyrus
He wrote a book on “uroscopy” in the 5th century BCE
Hippocrates
He discovered albuminuria in 1694
Frederik Dekkers
How did Frederik Dekkers discovered albuminuria?
By boiling urine
Charlatans without medical credentials that offer predictions to the public for a healthy fee
Pisse prophets
Author of the book where pisse prophets are the subjects
Thomas Bryant, 1627
This inspired the passing of the first medical licensure laws in England
Book of Thomas Bryant
This milestone led to the examination of urinary sediment
Invention of the microscope in the 17th century
He developed the methods for quantitating the microscopic sediment
Thomas Addis
He introduced the concept of urinalysis as part of a doctor’s routine patient examination in 1827
Richard Bright
Two unique characteristics of a urine specimen
- Urine is a readily available and easily collected specimen
- Urine contains information, which can be obtained by inexpensive laboratory tests, about many of the body’s major metabolic functions
How does the Clinical and Laboratory Standards Institute (CLSI) define urinalysis?
“The testing of urine with procedures commonly performed in an expeditious, reliable, accurate, safe, and cost-effective manner.”
Reasons for performing urinalysis identified by CLSI
Aiding in the diagnosis of disease
Screening asymptomatic populations for undetected disorders
Monitoring the progress of disease and the effectiveness of therapy
Organ that continuously form urine
Kidney
Average daily urine output
1200mL
The amount of filtered plasma converted by the kidney into average daily urine output
170,000mL
General composition of urine
95% water
5% solutes (urea, organic and inorganic chemicals)
Metabolic waste product produced in the liver from the breakdown of protein and amino acids
Urea
This metabolic product accounts for nearly half of the total dissolved solids in urine
Urea
Primary organic substances in urine
Urea
Creatinine
Uric acid
The major inorganic solid dissolved in urine
Chloride
Sodium
Potassium
Other substances found in urine include
Hormones
Vitamins
Medications
Formed elements that may be found in urine
Cells
Casts
Crystals
Mucus
Bacteria
Increased amounts of formed elements in urine are often indicative of
Disease
This factor determines the amount of urine to be excreted by the body
State of hydration
Substances that can identify a body fluid as urine
Creatinine
Urea
Primary organic component. Product of protein and amino acid metabolism
Urea
Product of creatine metabolism by muscles
Creatinine
Product of nucleic acid breakdown in food and cells
Uric acid
Primary inorganic component. Found in combination with sodium (table salt) and many other inorganic substances
Chloride
Primarily from salt, varies by intake
Sodium
Combined with chloride and other salts
Potassium
Combines with sodium to buffer the blood
Phosphate
Regulates blood and tissue fluid acidity
Ammonium
Combines with chloride, sulfate, and phosphate
Calcium
Factors that influence urine volume
Fluid intake
Fluid loss from nonrenal sources
Variations in the secretion of antidiuretic hormone
The need to excrete increased amounts of dissolved solids, such as glucose or salts
Normal daily urine output
1200 to 1500 mL, a range of 600 to 2000 mL is considered normal
A decrease in urine output (which is less than 1 mL/kg/hr in infants, less than 0.5 mL/kg/hr in children, and less than 400 mL/day in adults)
Oliguria
Oliguria is commonly seen when:
The body enters a state of dehydration as a result of excessive water loss from vomiting, diarrhea, perspiration, or severe burns
Cessation of urine flow
Anuria
Cause of anuria
Any serious damage to the kidneys or from a decrease in the flow of blood to the kidneys
Comparison of urine output during day and night
The kidneys excrete two to three times more urine during the day than during the night
An increase in the nocturnal excretion of urine
Nocturia
An increase in daily urine volume (greater than 2.5 L/day in adults and 2.5 to 3 mL/kg/day in children)
Polyuria
Diseases and factors associated with polyuria
Diabetes mellitus
Diabetes insipidus
Artificial diuretics
Caffeine
Alcohol
Disease caused by a defect either in the pancreatic production of insulin or in the function of insulin, which results in an increased body glucose concentration
Diabetes mellitus
Level of specific gravity of urine specimen from patient with diabetes mellitus
Increased
Disease that results from a decrease in the production or function of antidiuretic hormone (ADH); thus, the water necessary for adequate body hydration is not reabsorbed from the plasma filtrate
Diabetes insipidus
Concentration and specific gravity of urine specimen from patient with diabetes insipidus
Urine is dilute and has a low specific gravity
Compensatory mechanism for polyuria
Ingestion of water
An increased ingestion of water
Polydipsia
Container for urine specimen collection must be
Clean
Dry
Leak-proof
Reason for using disposable urine containers for collection
it eliminates the chance of contamination owing to improper washing
The recommended capacity of the urine specimen container
50mL
Amount of urine specimen needed for microscopic analysis
12mL
Suggested urine specimen container if more than 2 hours elapse between specimen collection and analysis is expected
Sterile urine containers
Why do we attach the label on the urine container and not on the lid?
Labels on the lid may lead to swapping, thus misidentification occurs
Criteria of specimen rejection
- Specimens in unlabeled containers
- Nonmatching labels and requisition forms
- Specimens contaminated with feces or toilet paper
- Containers with contaminated exteriors
- Specimens of insufficient quantity
- Specimens that have been improperly transported
Can we discard reject specimen even without consultation with a supervisor?
No
Following collection, specimens should be delivered to the laboratory promptly and tested within
2 hours
A specimen that cannot be delivered and tested within 2 hours should be
Refrigerated or have an appropriate chemical preservative added
The most routinely used method of urine preservation
Refrigeration at 2°C to 8°C
Purpose of refrigerating urine specimen
To reduce bacterial growth and metabolism
What are the requirements if the urine is to be cultured
It should be refrigerated during transit and kept refrigerated until cultured up to 24 hours
When refrigerated urine sample is to be chemically tested by reagent strips, the specimen must be:
The specimen must return to room temperature before chemical testing by reagent strips
Mode of specimen preservation when a specimen must be transported over a long distance and refrigeration is impossible
Addition of chemical preservatives
Ideal chemical preservative should be
Bactericidal
Inhibit urease
Preserve formed elements in the sediment
Must not interfere with chemical test
The reason why specimens must be returned to room temperature before chemical testing by reagent strips
The enzyme reactions on the strips perform best at room temperature
This is the most commonly received specimen because of its ease of collection and convenience for the patient
Random specimen
Purpose of random specimen
Routine screening
The ideal screening specimen
First morning specimen
Purpose of first morning specimen
Routine screening
Essential for preventing false-negative pregnancy tests
Evaluating orthostatic proteinuria
Specimen collected to correspond with the blood samples drawn during a glucose tolerance test (GTT)
Glucose tolerance specimens
Purpose of Glucose tolerance specimens
To assess patient’s ability to metabolize a measured amount of glucose and are correlated with the renal threshold for glucose
Specimen used to produce accurate quantitative results
Carefully timed specimen
Principle of 24-Hour (or Timed) Specimen
Patient must begin and end the collection period with an empty bladder
What to do if 24-hour urine specimen is collected using two separate containers
Contents should be combined and mixed thoroughly
Storage requirements for 24-hour specimen during collection
Must be refrigerated or kept on ice during the collection period
Purpose of 24-hour (or timed) specimen
Quantitative chemical tests
This specimen is collected under sterile conditions by passing a hollow tube (catheter) through urethra into the bladder
Catheterized specimen
The most commonly requested test on a catheterized specimen
Bacterial culture
Purpose of catheterized specimen
Bacterial culture
Alternative to the catheterized specimen that provides a safer, less traumatic method for obtaining urine for bacterial culture and routine urinalysis
Midstream clean-catch specimen
Purpose of Midstream clean-catch
Routine screening
Bacterial culture
It provides a specimen that is less contaminated by epithelial cells and bacteria and, therefore, is more representative of the actual urine than the routinely voided specimen
Midstream clean-catch specimen
Provides a sample for bacterial culture that is completely free of extraneous contamination
Suprapubic aspiration
Purpose of Suprapubic aspiration
Bladder urine for bacterial culture
Cytology
Purpose of Three-glass collection
Prostatic infection
Specimens using three-glass collection
Container 1 – first urine passed
Container 2 – midstream urine
Container 3 – remaining urine and prostatic fluid (post-massage urine)
Specimens in pre-and post-massage test (PPMT)
Specimen 1: midstream clean-catch specimen
Specimen: post-massage specimen
Positive result of pre- and post-massage test (PPMT) indicates
Bacteriuria in the post-massage specimen of greater than 10 times the premassage count
Most challenging specimen to collect
Pediatric specimens
Stamey-Mears 4-glass collection
Initial voided (VB1)
Midstream (VB2)
Massaged prostate excretions (EPS)
Post-massage urine (VB3)
What to do when both a routine urinalysis and a culture are requested on a catheterized or midstream collection
Culture should be performed first to prevent contamination of the specimen
How often do we need to check the applied bags when collecting pediatric specimen?
Every 15 minutes
The most vulnerable part of a drug-testing program
Urine specimen collection
In drug-testing program, this process provides the documentation of proper sample identification from the time of collection to the receipt of laboratory results
Chain of custody (COC)
Standardized form that must document and accompany every step of drug testing, from collector to courier to laboratory to medical review officer to employer
Chain of custody (COC)
During drug testing, urine specimen collections may be “witnessed” or “un-witnessed.” True or false
True
The decision to obtain a witnessed collection is indicated when
It is suspected that the donor may alter or substitute the specimen or it is the policy of the client ordering the test
Amount of urine specimen needed for drug testing
30-45mL
According to COC, urine temperature must be taken within
4 minutes from the time of collection
Why do we need to take the temperature of urine specimen during drug testing?
To confirm the specimen has not been adulterated
Ideal temperature of urine specimen for drug testing
32.5°C to 37.7°C
What to do if temperature of urine specimen is not within acceptable range?
Record the temperature
Report to supervisor
Recollect second specimen
A patient presenting with polyuria, nocturia, polydipsia, and a low urine specific gravity is exhibiting symptoms of:
Diabetes insipidus
A patient with oliguria might progress to having:
Anuria
Labels for urine containers are:
Attached to the container
Not detachable
A cloudy specimen received in the laboratory may have been preserved using:
Refrigeration
The primary advantage of a first morning specimen over a random specimen is that it:
More concentrated
If a routine urinalysis and a culture are requested on a catheterized specimen, then:
The culture is performed first
What will happen if a patient fails to discard the first specimen when collecting a timed specimen?
Results will be falsely elevated
What will happen if a patient fails to add the last specimen when collecting a timed specimen?
Results will be falsely decreased
The primary cause of unsatisfactory results in an unpreserved routine specimen not tested for 8 hours is:
Bacterial growth
Prolonged exposure of a preserved urine specimen to light will cause:
Decreased bilirubin
The most sterile specimen collected is a:
Suprapubic aspiration
Recommended cleansing materials/agents when collecting midstream clean-catch specimen
Mild antiseptic towelettes
Who discovered CSF
Domenico Cotugno
Who discovered Phenylketonuria
Ivan Folling
Who discovered Alkaptonuria
Archibald Garrod
Who discovered Cystine calculi
William Wollaston
Oliguria in infants
<1mL/kg/hour
Oliguria in children
<0.5 mL/kg/hour
Oliguria in adult
<400 mL/day
Polyuria in children
> 2.5-3 mL/kg/day
Polyuria in adult
> 2.5 L/day
Increased excretion of urine at night
Nocturia
Nocturia value
> 500 mL
SG of nocturnal urine
<1.018
Anuria value
<100 mL/24 hour
Urine specimen must be tested within
2 hours
What to do if urine specimen cannot be tested within 2 hours
Refrigerate at 2°C-8°C
What to do if urine specimen cannot be tested within 2 hours and refrigeration is not possible
Add preservatives
Cause of increased pH in unpreserved urine
Breakdown of urea to ammonia by urease-producing bacteria/loss of CO2
Cause of increased bacteria in unpreserved urine
Bacterial multiplication
Cause of increased odor in unpreserved urine
Bacterial multiplication causing breakdown of urea to ammonia
Cause of increased nitrite in unpreserved urine
Multiplication of nitrate-reducing bacteria
Cause of darkened color of unpreserved urine
Oxidation or reduction of metabolites
Cause of decreased clarity in unpreserved urine
Bacterial multiplication, precipitation of amorphous material
Cause of decreased glucose in unpreserved urine
Glycolysis and bacterial use
Cause of decreased ketones in unpreserved urine
Volatilization and bacterial metabolism
Cause of decreased bilirubin in unpreserved urine
Exposure to light/photo oxidation to biliverdin
Cause of decreased urobilinogen in unpreserved urine
Oxidation to urobilin
Cause of decreased RBC/WBC/Casts in unpreserved urine
Disintegration in dilute alkaline urine
The least affected parameter affected in unpreserved urine
Protein
Disadvantage of refrigeration
Precipitates amorphous phosphates and urates
Advantage of thymol
Preserves glucose and sediments well
Disadvantage of thymol
Interfere with acid precipitation test for protein
Advantage of boric acid
Prevents bacterial growth and metabolism
Disadvantage of boric acid
Interferes with drug and hormone analyses
Preservative that keeps pH at about 6.0 and can be used for urine culture transport
boric acid
Rinsing the specimen container with formalin helps to preserve cells and casts. True or False?
True
Advantage of formalin
Excellent sediment preservative
Disadvantage of formalin
Acts as a reducing agent, interfering with chemical tests for glucose, blood, leukocyte esterase, and copper reduction
Advantage of toluene
Does not interfere with routine test
Disadvantage of toluene
Floats on surface of specimens and clings to pipette and testing materials
Advantage of sodium fluoride
Is a good preservative for drug analyses
Disadvantage of sodium fluoride
Inhibits reagent strip tests for glucose, blood, and leukocytes
Urine preservative that causes a change in urine odor
Phenol
The second specimen voided
Fasting specimen
Use of fasting specimen
Recommended for glucose monitoring
Specimen collected 2 hours after eating
2 hour postprandial specimen
Use of 2 hour postprandial specimen
Monitors insulin therapy
Used for diabetic patients
Preferred urine specimen for urobilinigen measurements
Afternoon urine (2pm-4pm)
Ideal specimen for screening microalbuminuria
12 hours urine specimen
