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Lab Activity 32. Urinalysis. Portland Community College BI 233. Filtration. Occurs in the renal corpuscles: blood pressure forces water and small dissolved molecules to move from the glomerular capillaries to the capsular space and is called the filtrate. Filtrate.

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lab activity 32

Lab Activity 32

Urinalysis

Portland Community College

BI 233

filtration
Filtration
  • Occurs in the renal corpuscles: blood pressure forces water and small dissolved molecules to move from the glomerular capillaries to the capsular space and is called the filtrate
filtrate
Filtrate
  • Contains mostly water along with excess ions (mostly sodium and potassium), glucose, amino acids and nitrogenous waste products.
  • Lacks RBCs and large plasma proteins.
reabsorption
Reabsorption
  • Almost all the water (99%)
  • As well as glucose, amino acids and various ions.
  • These are returned to the blood by passing from the renal tubules to the peritubular capillaries or vasa recta
secretion
Secretion
  • Unwanted substances such as metabolic wastes, drugs and excess ions (hydrogen and potassium) are removed from the blood and enter the renal tubules.
  • Most occurs in DCT and collecting ducts
urine
Urine
  • Normally contains about 95% water
  • Various ions (sodium, potassium, sulfate, calcium, magnesium, bicarbonate)
  • Amino acids, lipids and carbohydrates
  • Urea, uric acid and creatinine
universal precautions
Universal precautions
  • You will be examining the physical and chemical characteristics of your own urine sample
  • Work with your urine only
  • Wear gloves, safety eyewear, and a mask
  • Clean spills with 10% bleach solution
  • Anything that comes into contact with urine goes into an autoclave bag.
physical characteristics of urine
Physical Characteristics of Urine
  • Color and transparency
    • Clear, pale to deep yellow (due to urochrome)
    • Concentrated urine has a deeper yellow/amber color
    • A red or red-brown (abnormal) color could be from a food dye, eating fresh beets, a drug, or the presence of either hemoglobin or myoglobin.
    • If the sample contained many red blood cells, it would be cloudy as well as red.
    • Turbidity or cloudiness may be caused by excessive cellular material or protein in the urine
physical characteristics of urine1
Physical Characteristics of Urine
  • Odor
    • Fresh urine is slightly aromatic
    • Standing urine develops an ammonia odor
    • Some drugs and vegetables (asparagus) alter the usual odor
    • Elevated ketones smells fruity or acetone-like
physical characteristics of urine2
Physical Characteristics of Urine
  • Specific gravity measures density of urine compared to water
  • Ranges from 1.001 to 1.035
    • 1.001 is dilute
    • 1.035 is concentrated
  • Is dependent on solute concentration
    • > 1.035 is either contaminated or contains very high levels of glucose
    • Patients who have received radiopaque dyes or dextran can also have high specific gravity
chemical composition of urine
Chemical Composition of Urine
  • Urine is 95% water and 5% solutes
  • Nitrogenous wastes include urea, uric acid, and creatinine
  • Other normal solutes include:
    • Sodium, potassium, phosphate, and sulfate ions
    • Calcium, magnesium, and bicarbonate ions
  • Abnormally high concentrations of any urinary constituents may indicate pathology
urinalysis
“Dipstick" method: chemical reactions cause color changes on ten different pads on the test strip.

Leukocytes

Nitrite

Urobilinogen

Protein

pH

Blood

Blood

Ketones

Bilirubin

Glucose

Urinalysis
dipstick urinalysis interpretation
Dipstick Urinalysis Interpretation

pH: large range 4.5 to 8.0 (average is 6.0)

  • The urine pH should be recorded, although it is seldom of diagnostic value.
    • Diet can alter pH
      • Acidic: high protein diet, ketoacidosis
      • Alkaline: vegetarian diet, UTI
dipstick urinalysis interpretation1
Dipstick Urinalysis Interpretation

Nitrite: Might indicate bacterial infection with gram-negative rods (like E. coli)

If bacteria are present, they convert nitrates to nitrites

Normal=negative

dipstick urinalysis interpretation2
Dipstick Urinalysis Interpretation

Bilirubin: indicates the presence of liver disease or biliary obstruction

A small amount of bilirubin in urine is normal excessive amounts is called

  • Bilirubinuria: appearance of bilirubin in urine
    • Yellow foam when sample is shake
dipstick urinalysis interpretation3
Dipstick Urinalysis Interpretation

Urobilinogen: Produced in the intestine from bilirubin. Gives feces brown color

Normal=small amount

  • Absence: renal disease or biliary obstruction
  • Increased in any condition that causes an increase in production or retention of bilirubin
    • Hepatitis, cirrhosis or biliary disease
dipstick urinalysis interpretation4
Dipstick Urinalysis Interpretation

Leukocytes: Indicates infection or inflammation

Normal=negative

  • Pyuria: Leukocytes in urine
  • Cystitis: Bladder infection
  • Pyelonephritis: Kidney infection
dipstick urinalysis interpretation5
Dipstick Urinalysis Interpretation

Blood: Almost always indicates pathology because RBC are too large to pass through glomerulus

Normal=negative

  • Hematuria: Blood in urine
  • Possible causes: Kidney stone, infection, tumor
  • Caution: Very common finding in women because of menstruation.
dipstick urinalysis interpretation6
Dipstick Urinalysis Interpretation

Protein: Usually proteins are too large to pass through glomerulus (Proteinuria usually represents an abnormality in the glomerular filtration barrier.)

Normal=negative

    • Trace amounts normal in pregnancy or after eating a lot of protein
  • Albuminuria: Albumin in urine
dipstick urinalysis interpretation7
Dipstick Urinalysis Interpretation

Glucose: In general the presence of glucose indicates that the filtered load of glucose exceeds the maximal tubular reabsorptive capacity for glucose. Normal=negative (can occur temporarily after eating a high carb meal or during stress)

  • Glycosuria: Glucose in urine
dipstick urinalysis interpretation8
Dipstick Urinalysis Interpretation

Ketones: Intermediate products of fat metabolism

    • Urine testing only detects acetoacetic acid, not the other ketones, acetone or beta-hydroxybuteric acid.
  • Normal=negative or trace amounts
    • Ketonuria: ketones in urine
  • (Ketonuria + glucose in urine may indicate diabetes mellitus)
urine sediments
Urine sediments
  • If a urine sample is centrifuged, the sediment can be viewed microscopically to examine the solid components.
  • Some solids are normally found in urine
chemical analysis
Chemical Analysis
  • Sulfates: Normal constituent of urine
    • The urinary sulfate is mainly derived from sulfur-containing amino acids and is therefore determined by protein intake.
  • Phosphates: Normal constituent of urine
    • Important for buffering H+ in the collecting duct
  • Chlorides: Normal constituent of urine.
    • Major extracellular anion.
    • Its main purpose is to maintain electrical neutrality, mostly as a counter-ion to sodium.
    • It often accompanies sodium losses and excesses.
sediments
sediments
  • Cells- small numbers of epithelial cells that are shed from various regions of the urinary tract.
  • Large numbers of WBSs and any amount of RBCs are abnormal usually indicate disease
microscopic examination pyuria wbc in urine
Microscopic ExaminationPyuria: WBC in Urine
  • Normal:
    • Men: <2 WBCs per hi power field
    • Women: <5
  • WBC generally indicate the presence of an inflammatory process somewhere along the course of the urinary tract
microscopic examination hematuria rbc in urine
Microscopic ExaminationHematuria: RBC in Urine
  • RBC's may appear normally shaped, swollen by dilute urine or crenated by concentrated urine.
  • The presence of dysmorphic (odd shaped) RBC's in urine suggests a glomerular disease such as a glomerulonephritis.

Crenated RBC

Dysmorphic RBC

microscopic examination epithelial cells
Microscopic Examination Epithelial Cells
  • Transitional epithelial cells originate from the renal pelvis, ureters, bladder and/or urethra.
  • Large sheets of transitional epithelial cells can be seen in bladder cancer.

Squamous epithelial cell

Transitional epithelial cell

microscopic examination casts
Microscopic ExaminationCasts
  • Casts: hardened cell fragments formed in the distal convoluted tubules and collecting ducts
  • Form when cells clump together
  • Usually form when urine is acidic or contains high level of proteins or salts
  • Usually pathological.
  • Can only be seen with microscopic examination
microscopic examination epithelial cells1
Microscopic ExaminationEpithelial Cells
  • Too many squamous cells: suggest contamination, poor specimen collection
white cell casts
White Cell Casts
  • Usually indicates pyelonephritis (kidney infection)
  • Other causes: Interstitial Nephritis (inflammation of the tubules and the spaces between the tubules and the glomeruli. )
red cell casts
Red Cell Casts
  • Red blood cells may stick together and form red blood cell casts.
  • Indicative of glomerulonephritis, with leakage of RBC's from glomeruli, or severe tubular damage.
hyaline casts
Hyaline Casts
  • Hyaline casts are composed primarily of a mucoprotein (Tamm-Horsfall protein) secreted by tubule cells.
  • Causes: Low flow rate, high salt concentration, and low pH, all of which favor protein denaturation and precipitation of the Tamm-Horsfall protein.

Hyaline Casts appear Transparent

calcium oxalate crystals
Calcium Oxalate Crystals
  • They can occur in urine of any pH.
  • Causes: Dietary asparagus and ethylene glycol (antifreeze) intoxication
uric acid crystals
Uric Acid Crystals
  • High uric acid in blood (by-product of purine digestion/high protein diet)
  • Associated with gout (arthritis)
struvite crystals
Struvite Crystals
  • Formation is favored in alkaline urine.
  • Urinary tract infection with urease producing bacteria (eg. Proteus vulgaris) can promote struvite crystals by raising urine pH and increasing free ammonia.
chemical analysis1
Chemical Analysis
  • Urea: The end product of protein breakdown
  • Uric acid: A metabolite of purine breakdown
  • Creatinine: Associated with muscle metabolism of creatine phosphate.
microscopic examination bacteria
Microscopic ExaminationBacteria
  • Bacteria are common in urine specimens (from contamination)
  • Therefore, microbial organisms found in all but the most scrupulously collected urines should be interpreted in view of clinical symptoms.

A = crenated RBC, B = RBC, C = bacteria

the end
The End

The End

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