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
What would cause increased levels of bilirubin in the urine?
Gallstones, extrahepatic duct obstruction (tumor, inflammation, gallstone, scarring, surgical trauma), extensive liver metastasis – direct physical obstruction of bile flow causes elevated serum levels of conjugated bilirubin (disease affecting bilirubin metabolism after conjugation & bilirubin is water soluble so it can be excreted in the urine.
Urine will be dark yellow or orange
What would cause increased levels of urobilirubin in the urine?
Hemolytic anemia, pernicious anemia, hemolysis due to drugs – hemolysis results in RBC destruction with more heme catabolized to bilirubin and more bilirubin excreted into the bowel, converted to urobilinogen, and reabsorbed from the gut.
Hematoma, excessive ecchymosis – RBCs break down in these areas
What would cause glucose to be present in the urine? (Should be negative normally)
Used as a screening test for diabetes mellitus or other causes of glucose intolerance (ex. pregnancy)
When blood glucose exceeds the ability of renal threshold to reabsorb glucose (about 180 mg/dL), it spills over into the urine.
Glucosuria may occur after eating a high carbohydrate meal or in patients receiving IV dextrose.
What are Nitrites used for?
What does a positive result indicate?
Screening test for UTI.
Many bacteria produce an enzyme called reductase which can reduce urinary nitrates to nitrites.
Positive test indicates possible need for a culture
What are in the microscopic examination of urine?
Crystals Casts Epithelial cells WBCs RBCs
What do crystals in the urine indicate?
Crystals indicate stone formation is happening or has already happened.
Uric acid crystals occur with high serum uric acid levels
Phosphate and calcium oxalate crystals occur with parathyroid abnormalities or malabsorption states
What are casts?
Casts are rectangular clumps of materials or cells formed in renal distal and collecting tubules.
pH must be acidic and urine must be concentrated.
Casts are usually associated with proteinuria and stasis in the renal tubules
What are the two major types of casts?
Hyaline Casts
Cellular
What are Hyaline casts? Indicate what?
Made of proteins and are indicative of proteinuria. The presence of a few are normal especially after exercise
What are Cellular casts?
What are the types of them?
Made of degenerated cells.
Types include granular, fatty, waxy, epithelial, WBC, and RBC
What can epithelial cells in the urine indicate?
Can shed from bladder due to tumor, infection, or polyps
Can be from contamination by vaginal or urethral secretions
What can WBCs in the urine indicate?
Few are normal, but 5 or more indicates UTI.
Differentiates cystitis from urethritis with two specimen technique – void 20 mL into one container and the rest into another – more WBCs in the first container indicates urethritis, more in the second container indicates cystitis
What can RBCs in the urine indicate?
Any disruption of blood urine barrier causes RBCs to enter the urine.
Hematuria may be microscopic or gross
Primary renal diseases (glomerulonephritis, acute tubular necrosis, pyelonephritis) – deterioration of blood-urine barrier
Renal tumor – neoplasms are friable and hypervascular
Renal trauma – lacerations, contusions, and hematomas
Kidney stones, bladder or prostate infection, tumors of ureters and bladder, traumatic catheterization, bladder trauma
Interfering Factors in regards to appearance and color?
Sperm in urethra after recent or retrograde ejaculation will cause cloudiness
Refrigerated urine > 1 hour will make urine cloudy
Foods can affect color (carrots = dark yellow, beets = red, rhubarb = reddish or brownish)
Prolonged standing will darken urine
Drugs
Interfering Factors in regards to odor?
foods (asparagus) or prolonged standing (ammonia)
Interfering Factors in regards to pH?
Prolonged standing produces alkaline urine due to urea splitting bacteria producing ammonia.
Uncovered specimen will become alkaline as carbon dioxide vaporizes.
Diet may affect the pH of the urine.
(Citrus fruits, cranberries, high meat -> acid)
(Dairy, vegetables -> alkaline)
Interfering Factors in regards to protein?
Contamination with prostate or vaginal secretions
Diets high in protein
Highly concentrated urine has higher concentration of protein
Interfering Factors in regards to Leukocyte esterase?
False positive results with contaminants from vaginal secretions (blood or discharge) that contain WBCs
Interfering Factors in regards to ketones?
Special diets (carbohydrate free, high protein, high fat) cause ketonuria
Interfering Factors in regards to Bilirubin and Urobilirubogen?
Bilirubin is not stable in urine, especially with light exposure
Phenazopyridine (Pyridium) colors urine orange – false impression of jaundice
Interfering Factors in regards to WBCs?
vaginal discharge contamination
Interfering Factors in regards to RBCs?
Traumatic catheterization causes RBCs
Overaggressive anticoagulant therapy or bleeding disorders
What do increased levels of specific gravity indicate?
Dehydration – kidneys absorb all available free water so urine is concentrated
Pituitary tumor or trauma – SIADH causes excessive water reabsorption
Glycosuria and proteinuria
What do decreased levels of specific gravity indicate?
Overhydration – excess water is excreted
Renal failure – kidney loses ability to concentrate urine through water reabsorption
Diuresis – diuretics cause dilute urine
What is a urine culture used for?
What is normal?
What do labs also report?
Used to diagnose UTI in patients with dysuria, frequency, or urgency. Also indicated with patients with fever of unknown origin or when UA suggests infection.
Normal: negative < 10,000 bacteria/ml urine; positive > 100,000 bacteria/mL urine.
Lab also reports sensitivity to various antibiotics of any bacteria growing
What are interfering factors for urine culture?
Contamination of urine with stool, vaginal secretions, hands, or clothing will cause false positive results
Drugs including other antibiotics may affect results
What is urine osmolality used for?
Normal range?
Used to evaluate fluid and electrolyte abnormalities – determines the kidney’s concentrating capabilities.
Used to evaluate ADH abnormalities (diabetes insipidus) and inappropriate ADH secretion.
Normal range: 12-14 hour fluid restriction > 850 mOsm/kg H2O; random specimen 50-1200 mOsm/kg H2O
What is more exact urine osmolality or specific gravity?
Urine Osmolality is more exact measurement of urine concentration than specific gravity.
SG depends on weight and density of particles in the urine and requires correction for presence of glucose or protein as well as temperature.
Osmolality only depends on number of particles of solute in a unit of solution
What causes increased levels of urine osmolality? (More concentrated)
SIADH – ADH inappropriately secreted so large amounts of water are reabsorbed by the kidney.
Paraneoplastic syndromes due to carcinoma (lung, breast, colon) – autonomous ectopic source for secretion of ADH.
Shock – kidneys absorb all free water possible to minimize loss of free body water.
Hepatic cirrhosis, CHF – water retention due to reduced perfusion of kidneys
What causes decreased levels of urine osmolality? (More dilute)
Diabetes insipidus – insufficient secretion of ADH diminishes kidney’s ability to concentrate urine.
Excess fluid intake – free water overload is excreted into the urine.
Renal tubular necrosis, severe pyelonephritis – concentrating ability of kidneys is reduced
What is Urine Drug Testing and Toxicology used for?
Used to identify metabolites of illegal drugs used by person being tested.
Drug screen is typically performed to detect small amounts of metabolites of commonly used drugs
If positive then a more accurate quantitative test can be performed on the same specimen
What are the most common substances screened for in Urine Drug Testing and Toxicology?
Amphetamines Barbiturates Benzodiazepines Cocaine Opiates Cannabinoids Phencyclidine (PCP) Sometimes tricyclic antidepressants
What are the interfering factors in Urine Drug Testing and Toxicology?
Poppy seeds can cause false positive opiate results.
Second hand marijuana smoke can cause false positive results.
Cold remedies can cause false positive amphetamine or opiate result.
Aggressive diuretic use can decrease drug levels in the urine
What is measuring sodium in the urine used for?
Normal values?
Evaluate fluid and electrolyte abnormalities , especially Na+.
Useful in evaluating volume depletion, acute renal failure, adrenal disturbances, acid-base imbalances
Normal (24 hours): 40-220 mEq/day
What causes increased levels of sodium in the urine?
Dehydration : Free water reabsorbed by kidney, urine Na+ more concentrated
Adrenocortical insufficiency: Aldosterone & corticosteroids cause Na+ reabsorb. W/o these hormones Na+ will not be reabsorbed”
Diuretic Therapy: Diminish Na+ reabsorb & increase Na+ loss
Syndrome of Inappropriate ADH (SIADH): ADH stimulates water reabsorb, have high ADH so Na+ more concentrated
Diabetic Ketoacidosis: Osmotic diuresis due to hyperglycemia -> diminish Na+ reaborb
Chronic Renal Failure: Renal reabsorption of Na+ is diminished
What causes decreased levels of sodium in the urine?
Congestive Heart Failure: Renal blood flow diminished b/c reduced cardiac output. Renin-angiotensin system activated, aldosterone production stimulated -> reabsorb Na+”
Malabsorption, Diarrhea: Intestinal absorption of Na+ reduced, so reduce Na+ loss in urine
Cushing’s disease: Corticosteroids have aldosterone like effect on kidney -> reabsorb Na+
Aldosteronism: Aldosterone stimulates Na+ reabsorption
What are the interfering factors for sodium in the urine?
Dietary Salt Intake may increase
Drugs may increase or decrease
What is measuring Potassium in the urine used for?
Normal values?
Evaluate electrolyte (esp. hypokalemia) balance, acid-base balance & renal and adrenal diseases
Normal: 25-100 mEq/L/day
What causes increased levels of potassium in the urine?
Chronic Renal Failure: Na+ loss increased, K+ loss follows Na+ loss
Renal tubular acidosis: Reduced excretion of H+ increases excretion of K+
Starvation: Protein & fat containing tissues broken down -> cells expell K+ into blood, so K+ excreted in urine
Cushing syndrome, Hyperaldosteronism: Aldosterone & glucocorticoids increases K+ excretion
Excessive intake of Licorice: Licorice has and Aldosterone like effect
Alkalosis: H+ reabsorbed in kidney in exchange for K+
Diuretic therapy: increase K+ excretion
What causes decreased levels of potassium in the urine?
Dehydration: Decreased renal blood flow, diminishes K+ excretion
Addison disease: diminished aldosterone (aldosterone usually ^ K+ excretion), reduced K+ excretion
Malnutrition, vomitting, diarrhea, malabsorption: Diminished intake of K+
Acute renal failure: urinary excretion of K+ diminished. Most common cause of hyperkalemia
What are the interfering factors for potassium in the urine?
Dietary intake
Excessive Intake of Licorice increases K+ excretion
Drugs may increase
What is measuring Chloride in the urine used for?
Normal values?
Indicate state of electrolyte or acid/base imbalance
Measure effectiveness of diets with restricted salt (NaCl)
Normal: 110-250mEq/day
What causes increased levels of Chloride in the urine?
Dehydration, starvation, diuretic therapy, Addison disease: (Na+ followed by Cl-) reabsorption is decreased
Increased Salt intake, Intravenous saline infusion: Output = input, so Cl- excretion increases to maintain
homeostasis
What causes decreased levels of Chloride in the urine?
Cushing syndrome, Conn Syndrome, Steroid therapy, Congesitve Heart Failure: (Na+ followed by Cl-) so reabsorption is increased
Malabsorption syndrome, Prologned gastric suction or vomiting, diarrhea, pyloric obstruction, Diaphoresis, Reduced Salt intake: Serum Cl- levels decreased, so excretion decreased
What are the interfering factors for Chloride in the urine?
Urine volume and preparation
Dietary salt intake or saline infusion
Drugs may increase
What is measuring Cortisol in the urine used for?
Normal values?
Suspected hyperfunction or hypofunction of adrenal gland
Normal: < 100 mcg/24 hr or <276 nmol/day
What causes increased levels of Cortisol in the urine?
Cushing disease, Ectopic ACTH-producing tumors, stress: ACTH overproduced, cortisol levels rise
Cushing syndrome (adrneal adenoma or carcinoma): neoplasms produces cortisol
Hyperthyroidism: Metabolic rate increased, cortisol levels rise to maintain glucose needs
Obesity: All sterols increasedd
What causes decreased levels of Cortisol in the urine?
Adrenal hyperplasia: Congenital absence of enzymes that synthesize cortisol
Addison Disease: hypofunctiong adrenal gland, cortisol decreases
Hypopituitarism: ACTH not produced, so adrenal gland not stimulated
Hypothyroidism: Normal cortisol levels not required for reduced metabolic rate
What are the interfering factors for Cortisol in the urine?
Pregnancy causes increase
Physical and emotional stress cause increase
Drugs can increase or decrease
What is measuring 17-Hydroxycorticoidsteroid (17-OCHS) in the urine used for?
Normal values?
Assess adrenocortical function by measuring cortisol metabolites (17-OCHS).
Indirect measurement of adrenal function
Normal: Male: 3-10 mg/24 hr or 8.3-27.6 mmol/day
Female: 2-8 mg/24 hr or 5.2-22.1 mmol/day
What causes increased levels of 17-Hydroxycorticoidsteroid (17-OCHS) in the urine?
Cushing disease, Ectopic ACTH-producing tumor: overproduction ACTH
Stress: Stimulates ACTH production, 17-OCHS rises
Cushing Syndrome (adrenal adenoma or carcinoma): Neoplasm produce cortisol, 17-OCHS rises
Hyperthyroidism: Metabolic rate increase, cortisol and 17-OCHS rises to maintain glucose needs
Obesity: All sterols increased
What causes decreased levels of 17-Hydroxycorticoidsteroid (17-OCHS) in the urine?
Adrenal hyperplasia: Congenital absence of enzymes that synthesize cortisol
Addison Disease due to adrenal infarcation, adrenal hemorrhage, surgical removal of adrenal glands, congenital enzyme deficiency or adrenal suppression from steroid therapy: hypofunctiong adrenal gland, cortisol decreases and 17-OCHS decreases
Hypopituitarism: ACTH not produced, so adrenal gland not stimulated
Hypothyroidism: Normal cortisol levels not required for reduced metabolic rate
What are the interfering factors for 17-Hydroxycorticoidsteroid (17-OCHS) in the urine?
Emotional and Physical stress (e.g. infection) and licorice ingestion -> increased adrenal activity
Drugs may increase or decrease
Is cortisol or 17-OCHS more acurate?
Urine and plasma levels of cortisol are more accurate
