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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


Portland Community College

BI 233

  • 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
  • Contains mostly water along with excess ions (mostly sodium and potassium), glucose, amino acids and nitrogenous waste products.
  • Lacks RBCs and large plasma proteins.
  • 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
  • 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
  • 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
“Dipstick" method: chemical reactions cause color changes on ten different pads on the test strip.











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


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


  • 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


  • 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.)


    • 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.
  • 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