Urinalysis Lecture – Key Vocabulary

Vocabulary flashcards summarizing essential terms and definitions from the Clin Path 2 Urinalysis lecture.

Urinalysis

Laboratory evaluation of urine’s physical, chemical, and microscopic properties.

Kidney

Paired organ that filters blood, forms urine, and maintains homeostasis.

Nephron

Functional unit of the kidney composed of renal corpuscle and tubules.

Renal Corpuscle

Portion of nephron containing the glomerulus and Bowman’s capsule.

Glomerulus

Tuft of fenestrated capillaries that filters blood in the kidney.

Bowman’s Capsule

Cup-shaped structure that collects filtrate from the glomerulus.

Afferent Arteriole

Small artery bringing blood into the glomerulus.

Efferent Arteriole

Vessel carrying blood away from the glomerulus.

Filtrate

Fluid that passes through the glomerular membrane into Bowman’s capsule.

Proximal Convoluted Tubule (PCT)

First nephron segment where 100 % of glucose and most water, electrolytes, amino acids are reabsorbed.

Loop of Henle (Nephron Loop)

U-shaped tubule with descending water-permeable limb and ascending water-impermeable limb.

Distal Convoluted Tubule (DCT)

Nephron segment variably permeable to water; site of fine-tuning of filtrate.

Collecting Duct

Tubule that receives filtrate from nephrons; water reabsorption regulated by ADH and aldosterone.

Fenestrations

Pores in glomerular capillary walls allowing small molecules to pass.

Erythropoietin

Kidney-produced glycoprotein hormone stimulating red blood cell production.

Renin

Proteolytic enzyme from juxtaglomerular cells initiating the renin–angiotensin cascade.

Renin–Angiotensin System

Hormonal pathway that increases blood pressure and stimulates aldosterone release.

Antidiuretic Hormone (ADH, Vasopressin)

Posterior pituitary hormone that conserves body water by increasing renal water reabsorption.

Aldosterone

Adrenal cortical mineralocorticoid that promotes sodium retention and potassium excretion.

Diabetes Insipidus

Polyuric disorder caused by ADH deficiency (central) or renal unresponsiveness (nephrogenic).

Polyuria

Excessive urine volume production.

Oliguria

Decreased urine output.

Anuria

Complete absence of urine production.

Specific Gravity (SG)

Density of urine compared with water; indicator of urine concentration.

Isosthenuria

Urine SG equal to protein-free plasma (~1.008–1.012); kidneys not concentrating.

Refractometer

Instrument providing the most reliable measurement of urine specific gravity.

Urinometer

Float device requiring large volume to measure urine SG.

Dipstick (Reagent Strip)

Plastic strip with reagent pads for rapid urine chemistry testing.

Proteinuria

Presence of excess protein in urine, detected by dipstick color change.

Glucosuria

Glucose in urine, occurring when blood glucose exceeds renal threshold (~170–180 mg/dl).

Ketonuria

Presence of ketone bodies in urine, seen with diabetes mellitus or starvation.

Bilirubinuria

Conjugated bilirubin detected in urine; small amounts normal in male dogs.

Hematuria

Intact red blood cells in urine indicating urinary tract bleeding.

Hemoglobinuria

Free hemoglobin in urine due to intravascular hemolysis.

Myoglobinuria

Myoglobin in urine from muscle breakdown (e.g., equine rhabdomyolysis).

Nitrite Test

Dipstick pad that suggests bacteriuria by detecting nitrate-reducing bacteria; unreliable in animals.

Leukocyte Esterase Test

Pad detecting white-cell enzymes; insensitive in dogs, often false-positive in cats.

Microscopic Urine Sediment

Centrifuged solid portion examined for cells, casts, crystals, microorganisms, artifacts.

Red Blood Cell (RBC)

Small biconcave discs; normal 2-3/HPF in urine sediment.

White Blood Cell (WBC)

Larger granular cells; normal 0-1/HPF; excess = leukocyturia/pyuria.

Squamous Epithelial Cell

Large flat cells from distal urethra or genital tract; usually insignificant.

Transitional Epithelial Cell

Pear-shaped cells from bladder, ureters, renal pelvis; ↑ with cystitis or catheterization.

Renal Epithelial Cell

Small round cells with large nucleus from renal tubules; ↑ indicates renal parenchymal disease.

Cast

Cylindrical structure formed in renal tubules composed of Tamm-Horsfall protein ± cells.

Hyaline Cast

Clear, protein-only cast; can be normal (0–2/lpf) or indicate fever, exercise.

Granular Cast

Cast containing degenerated cellular debris; suggests renal tubular damage.

Waxy Cast

Smooth, refractile, brittle cast indicating chronic tubular degeneration.

Red Cell Cast

Cast filled with RBCs; indicates renal bleeding (glomerulonephritis).

White Cell Cast

Cast containing WBCs; indicates renal inflammation or pyelonephritis.

Fatty Cast

Cast with lipid droplets, common in cats or nephrotic syndrome.

Crystalluria

Presence of crystals in urine; influenced by pH, concentration, temperature.

Struvite Crystal (Magnesium Ammonium Phosphate)

Colorless “coffin-lid” crystal forming in alkaline urine; common in dogs/cats.

Calcium Oxalate Dihydrate

Envelope-shaped crystal (Xbox); forms in any pH; common and radiopaque.

Calcium Oxalate Monohydrate

Picket-fence or spindle crystal; abundant with ethylene glycol poisoning.

Calcium Carbonate Crystal

Dumbbell or round crystal typical in equine urine.

Uric Acid Crystal

Yellow-brown rhomboid; seen in Dalmatians with altered purine metabolism.

Ammonium Biurate (Thorny Apple)

Brown spherical crystal with spicules; associated with portal vascular anomalies.

Cystine Crystal

Colorless hexagonal crystal; always pathologic, linked to cystinuria.

Cholesterol Crystal

Large rectangular plate with notch; occasionally in dogs’ urine.

Leucine Crystal

Yellow-brown concentric spheres; rare, indicates severe liver disease.

Sulfonamide Crystal

Needle or fan-shaped crystal in animals on sulfa drugs.

Radiopaque

Visible on plain radiographs (e.g., struvite, calcium oxalate stones).

Radiolucent

Not visible on plain radiographs (e.g., urate, cystine stones).

Urolith

Polycrystalline stone composed mainly of minerals with <5 % matrix.

Urethral Plug

Obstructive mix of abundant matrix and minerals, common in male cats.

Struvite Urolith

Hard white-yellow radiopaque stone forming in alkaline urine; often infection related.

Calcium Oxalate Urolith

Hard radiopaque stone with sharp projections; forms in acidic urine.

Cystine Urolith

Smooth yellow radiolucent stone resulting from inherited tubular defect.

Urate Urolith

Yellow brittle radiolucent stone; common in Dalmatians or with liver shunts.

Silicate Urolith

Jack-stone radiopaque calculi linked to diets high in plant ingredients.

Dried Solidified Blood Stone

Radiolucent mass formed chiefly from clotted blood; reported in cats.

Voided Sample

Urine collected during spontaneous urination; highest contamination risk.

Free-Catch Sample

Voided urine caught midstream using bowl, ladle, or pan.

Bladder Expression

Manual compression of bladder to obtain urine; may cause trauma or contamination.

Catheterization

Insertion of sterile catheter through urethra to collect urine or relieve obstruction.

Cystocentesis

Percutaneous needle aspiration of urine from bladder; yields sterile sample.

Midstream Collection

Discarding initial urine flow to reduce contamination in voided samples.

Morning Sample

First urine of the day; typically most concentrated for analysis.

Polycrystalline

Composed of many mineral crystals, as in uroliths.

Matrix (urolith)

Organic component (<5 %) binding crystals within a stone; more abundant in plugs.

Calculolytic Diet

Therapeutic food formulated to dissolve existing uroliths (e.g., struvite).

Hydropropulsion

Flushing technique to expel small uroliths via catheter and saline.

Acid Urine

Urine pH <7; favors formation of calcium oxalate and cystine stones.

Alkaline Urine

Urine pH >7; favors struvite and calcium phosphate crystal formation.

Occult Blood

Microscopically invisible hematuria detected by reagent strips.

Brownian Movement

Random vibration of small particles (e.g., bacteria) in fluid.

Tamm–Horsfall Protein

Glycoprotein secreted by renal tubules; scaffold for hyaline casts.

Urobilinogen

Reduced bilirubin product from gut bacteria; small amounts normal in urine.

Alkaline Tide

Post-prandial transient rise in urine pH.

Leukocyturia

Presence of excessive white blood cells in urine sediment.

Pyuria

Pus (many WBCs) in urine, synonymous with marked leukocyturia.

Crystallography

Analytical method to identify stone mineral composition via X-ray diffraction.

Minnesota Urolith Center

Reference lab offering quantitative analysis of veterinary uroliths.

Urease-Producing Bacteria

Microbes (e.g., Proteus) that split urea, raising urine pH and promoting struvite.

Thiol-Disulfide Exchange Drug

Medication (e.g., tiopronin) used to manage cystine urolithiasis.

Hydrophobic Cat Litter

Special litter that repels urine, facilitating non-absorbent sample collection.

Brownish Foam

Surface froth suggesting bilirubin in urine.

Diuretic Therapy

Administration of drugs increasing urine output, lowering specific gravity.

Occultist Reagent Tablet

Confirmatory test distinguishing blood pigments in urine.

“Coffin-Lid”

Descriptive nickname for struvite crystal shape.