Urine Flashcards
What is urine derived from?
What is it mainly?
Urine is derived from filtration of blood by the nephrons in the kidneys.
Urine is mainly water with a small percentage of solutes.
All end products of metabolism and all potentially harmful materials are excreted in the urine
What does urine generally reflect?
Urine generally reflects blood levels – if blood level for a substance is elevated and kidneys are functioning well, the urine level will also be high
What are the reasons for Urine Testing
To diagnose renal or urinary tract disease (proteinuria may indicate glomerulonephritis).
To monitor renal or urinary tract disease (urine cultures to monitor treatment of UTI).
To detect metabolic or systemic diseases not directly related to the kidneys (glucose in the urine may indicate diabetes)
When may urinalysis be preferred over blood tests?
Identification of UTI
24 hour urine collection will reflect homeostasis and disease better than a blood test
Some products are rapidly cleared by the kidneys and may not show in the blood
Urine testing is easily performed and noninvasive
Many urine tests are cheaper than blood tests
What are the 5 types of urine specimens?
First morning specimen Random specimen Timed urine collection Double voided specimen Urine specimen for culture and sensitivity
What is the first morning specimen?
Urine in the bladder overnight represents all of the urine for the previous 6-8 hours so more accurately reflects a 24 hour urine.
First morning specimen allows diurnal variation to be factored in.
Urine will be concentrated and more likely to detect positive findings, such as proteins and nitrates and pregnancy.
Disadvantage: Not the most convenient to obtain. Patient must be given instructions and collection container in advance. Specimen must be preserved if not delivered within 2 hours of collection
What is the Random Specimen?
Obtained during daytime hours without any preparation.
Most often used for routine screening .
Also used for illegal drug screening.
What is the timed urine collection specimen?
Two types of timed collections:
Specimen collected at a predetermined time (2 hours after a meal).
Specimen collected at a specific time of day.
To collect the specimen, the patient voids and discards the first specimen to start the test. All subsequent urine is collected and at the end of the time period the patient voids to complete the collection process
Can range from 2-24 hours
Why use a timed urine collection specimen?
Hormones, proteins, and electrolytes are variably excreted over 24 hours and are affected by exercise, posture, hydration, and body metabolism, so quantitative tests may require a timed collection.
What is the double voided specimen?
Used to obtain and evaluate fresh urine.
Used to monitor glucose and ketones.
Patient first empties the bladder and then voids again, which is the specimen that is used
What is the Urine Specimen for culture and sensitivity?
Collected for examination of bacteria.
Must be in a sterile container and placed as aseptically as possible.
Meatus must be cleaned and a midstream collection will cleanse the urethral canal of contaminant bacteria.
Culture should be started within 1 hour of collection.
What are the two MAIN types of collection methods?
Common methods
Special methods
What are the common collection methods?
Routine void specimen
Midstream and clean catch specimens
24 hour collection
What are the special collection methods?
Urethral catheterization
Suprapubic aspiration
Pediatric collections
What is the routine void specimen?
No preparation required.
Nonsterile.
Random and first morning specimens are collected this way
What is the Midstream and clean catch specimen?
Used if culture and sensitivity study is required or if likely to be contaminated by vaginal discharge or bleeding.
Meatus must be cleansed to reduce contamination.
For midstream, patient begins to urinate to wash out the distal urethra and then stops. Then the patient voids into a sterile container.
What is the 24 hour collection?
Discard the first specimen to start the 24 hour collection.
Collect all urine for the next 24 hours, ending with the specimen at the end of 24 hours
Specimen should be refrigerated during collection
All urine in that 24 hour period must be collected
What is the Urethral catheterization?
This may cause infection.
Used when patients are unable to void or cannot void when the specimen is required.
In patients with an indwelling catheter in place, the specimen is obtained from the catheter distal to the sleeve leading to the balloon.
Urine in the reservoir bag should never be used
What is the Suprapubic aspiration?
Insert needle through the abdominal wall into the bladder
What is the Pediatric collections?
Pediatric collection bag
What does the urine reagent strip estimate?
How is it performed?
Estimates glucose, albumin, hemoglobin, and bile concentrations, as well as urinary pH, specific gravity, protein, ketone bodies, nitrates, and leukocyte esterase.
Strip of paper is dipped into the urine and observed for color changes on the strip and compared to the color chart on the bottle of the test strips
When is Urinalysis (UA) done?
Part of routine diagnostic and screening evaluations.
Routinely done on patients admitted to the hospital, pregnant women, and presurgical patients.
Done diagnostically in patients with abdominal pain, back pain, dysuria, hematuria, or urinary frequency.
Also part of routine monitoring in patients with chronic renal disease and some metabolic diseases
What are Urinalysis (UA) normal findings?
Those performed by dipstick i.e. Appearance, color, pH, proteins, glucose
Appearance – clear Color – amber yellow Odor – aromatic pH- 4.6-8.0 Protein - 0-8 mg/dL; 50-80 mg/24 hours Specific gravity – 1.005 – 1.030 Leukocyte esterase – neg Nitrites, ketones, bilirubin, crystals, casts – none Urobilinogen – 0.01 -1 Ehrlich unit/mL Glucose – Fresh specimen – none; 24 hour specimen – 50-300 mg/24 hours
What are Urinalysis (UA) normal findings?
Those performed microscopically i.e. cells
WBCs – 0-4 per low power field WBC casts – none RBCs – less than or equal to 2 RBC casts - none Bacteria – none Crystals - none
What does color of urine indicate?
Urine may be pale yellow to amber.
Color indicates the concentration of the urine and varies with specific gravity.
Dilute urine is straw colored and concentrated urine is deep amber
What does cloudy urine indicate?
Normal urine is clear. Cloudiness may be caused by pus (necrotic WBCs), RBCs, or bacteria or from ingestion of certain foods
What could cause abnormal appearance and color results?
Infection – may cause turbid, foul smelling urine
Gross hematuria – trauma, tumors, stones, infection, and renal pathology. (Bleeding from the kidneys produce dark red urine while bleeding from the lower tract produces bright red urine.)
Overhydration, diuretic therapy, glycosuria – clear urine
Fever, dehydration, jaundice (Urobilinogen or bilirubin) – dark yellow or orange urine
Hemoglobinuria, myoglobinuria – wine colored or dark brown urine
Drug therapy
Beets may cause red urine, and rhubarb may cause brown urine
What causes the normal odor of urine?
What pathological conditions cause abnormal odors?
Aromatic odor of normal urine is caused by volatile acids.
Abnormal:
DKA patient’s urine (Ketoonuria) has a strong, sweet smell of acetone (Fruity) due to poor glucose tolerance
UTI may have a foul odor
Enterovesical fistula (Colon to bladder connection) – stool odor
What is urine pH helpful in looking for or showing?
Urine reflects the kidneys maintaining normal pH homeostasis. The kidneys assist in acid-base balance by reabsorbing sodium and excreting hydrogen
pH also is helpful in identifying crystals in urine and determining predisposition to form certain types of kidney stones
What can cause acidic urine (Decreased pH)?
Acidemia from metabolic or respiratory acidosis, starvation, dehydration.
Diabetes mellitus, starvation – ketone acids in urine.
Respiratory acidosis – hydrogen ions excreted
Associated with uric acid and calcium oxalate stones – treatment is to keep the urine alkaline
What can cause alkaline urine (Increased pH)?
Alkalemia.
UTI - urea splitting bacteria convert urea to ammonia.
Gastric suction, vomiting, renal tubular acidosis – reduced hydrogen ion excretion causing increased pH
Associated with other calcium and magnesium salts that form stones – treatment is to keep the urine acidic
What can cause abnormal protein levels in urine?
Nephrotic syndrome , glomerulonephritis, malignant hypertension, nephrotoxic drug therapy. If the glomerular membrane is injured (glomerulonephritis), spaces in the glomerular filtrate membrane become larger and protein can seep through. This can lead to hypoproteinemia if it persists at a significant rate and lead to decreased capillary oncotic pressure to cause interstitial edema (nephrotic syndrome).
Trauma – destruction of blood-urine barrier allows protein to spill into urine.
Multiple myeloma – large amount of protein (Bence-Jones protein) in urine.
Preeclampsia, CHF – albumin leaks from damaged glomeruli.
Urethritis or prostatitis – inflammation in periurethral glands or urethra
What degree of protein loss leads to signs and symptoms of nephrotic syndrome?
Protein loss of more than 3000 mg/24 hours leads to signs and symptoms of nephrotic syndrome
It is sensitive indicator of kidney function, not normally present in the urine.
What does Specific gravity measure?
Measures concentration of particles in the urine
Used to evaluate the concentrating and excretory power of the kidneys.
Renal disease diminishes the kidneys’ ability to concentrate urine, leading to low specific gravity.
Assesses hydration.
A high specific gravity indicates concentrated urine and a low specific gravity indicates dilute urine
What is leukocyte esterase used for?
What does a positive result indicate?
Screening test to detect WBCs in the urine.
Positive results indicate a UTI.
In some labs, microscopic exam is only done if this test is positive
Has about a 90% accuracy for detecting WBCs in the urine
What would cause high levels of ketones in the urine?
Poorly controlled diabetics and those with hyperglycemia, alcoholism, fasting, starvation, prolonged vomiting and high protein diets due to impaired glucose metabolism causes catabolism of fat for production of energy to form ketones which spill into the urine.
Acute febrile illnesses, especially in infants and children or severe stress or illness -hypermetabolic states cause excessive use of glucose so fats are then broken down
