Urinalysis and Hematology Review - Flashcards

A set of practice flashcards covering urinalysis, specimen collection, urinalysis interpretation, urine sediment, crystals, uroliths, and hematology concepts from the notes.

What does a complete urinalysis include?

Evaluation of the physical, chemical, solute, and microscopic components of urine; may include microbiological cultures, sensitivity testing, and identification of urinary calculi.

Why is pre-analytical care important in urinalysis?

Because pre-analytical patient variables, specimen collection, handling, and timing influence results.

What is the primary use of urinalysis in patient evaluation?

To assess the urinary system and aid diagnosis of non–urinary tract disorders, including screening, monitoring, and evaluating treatment efficacy.

What substances are endogenous in urine analysis?

Uric acid, amino acids, hormones, and electrolytes.

What substances are exogenous in urine analysis?

Creatinine clearance and phenolsulfonphthalein dye.

In qualitative (and semi-quantitative) urinalysis, is the outcome affected by the rate of urine formation?

No; the outcome is not affected by the rate of urine formation over a specific time.

What factors influence quantitative urinalysis outcomes?

Volume collected, time, and conditions during collection.

What should be included in a urine specimen container for lab work?

A clean (preferably sterile), dry, opaque container with a tight lid to prevent contamination and light degradation.

Why should sterile containers be used for urine samples from cystocentesis or catheterization?

To prevent contamination, especially for bacterial culture.

What timing considerations affect urine formation and collection?

Formation in the bladder, collection timing (fasted, postprandial, random, serial), and potential concentration differences.

What is the recommended postprandial sampling window that may reflect diet?

A 3- to 6-hour postprandial sample.

How soon should a urinalysis ideally be performed after collection?

Within 20 to 30 minutes of collection.

What is Point-of-Care Testing (POCT) relevance in urinalysis?

POCT can increase accuracy and speed of urinalysis results.

Name primary methods of urine collection discussed.

Free flow (clean catch), cystocentesis, transurethral catheterization, metabolism cage, litter pan, tabletop/cage/floor samples, and client-collected samples.

Why is a midstream (free-flow) sample preferred for some analyses?

Simple and noninvasive, but not satisfactory for bacterial culture.

What is cystocentesis?

Inserting a needle through the ventral abdomen into the bladder using aseptic technique to obtain urine, minimizing contamination for culture.

What is transurethral catheterization?

Passing a catheter through the urethra into the bladder; sample is aspirated into a syringe; aseptic technique is essential.

What collection method is often best for bacterial culture?

Cystocentesis sample collection.

How should urine be preserved for microscopic evaluation?

Centrifuge immediately; refrigerate at ~2–8°C for 2–12 hours if needed; bring to room temperature before evaluation.

Does freezing urine affect cellular elements?

Yes; freezing (≤32°F/0°C) is satisfactory for many chemical analytes but destroys cellular elements.

What are common chemical urine preservatives mentioned?

Acidifiers (e.g., boric acid, hydrochloric acid), formaldehyde, toluene, thymol, phenol, chloroform, sodium fluoride; these may preserve some elements but affect others.

How long should urine be analyzed after collection to maximize validity?

Within 20 to 30 minutes to minimize pre-analytical variables.

What does pre-collection and post-collection iatrogenic variability cause?

Increases or decreases in results, leading to false-positive or false-negative results.

Define anuria.

Complete absence of urine formation or elimination.

Define continence in urinary terms.

Storage of urine in the bladder as it fills.

Define dysuria.

Difficulty or pain on urination.

Define incontinence.

Dribbling of urine at frequent intervals.

Define micturition.

Physiological term for emptying the bladder (urination).

Define oliguria.

A decrease in the formation or elimination of urine.

Define pollakiuria.

Frequent urination.

Define polyuria.

Formation and excretion of large volumes of urine.

What pigments primarily color urine yellow?

Urochrome pigments; urobilinogen can also influence color.

How is urine turbidity described?

As clear, hazy, cloudy, turbid, opaque, or flocculent (large particulates settle).

What causes cloudy urine?

Cellular debris, RBCs, WBCs, epithelial cells, crystals, bacteria, casts, mucus, lipids; standing may promote cloudiness.

Which odor is associated with urease-producing bacteria?

Ammoniacal odor.

What is the practical use of urine specific gravity (USG)?

To assess the kidney's ability to concentrate or dilute filtrates; interpreted with hydration, BUN, and creatinine.

What does SG indicate when recorded as -sthen, iso-, hypo-, and hyper-?

Strength/concentration relative to plasma: isosthenuria (~1.008–1.012), hyposthenuria (

What is isosthenuria?

Fixed SG around 1.008–1.012, glomerular filtrate SG equals plasma SG.

What is hyposthenuria?

SG < ~1.008; tubules dilute urine below plasma SG; osmolality < plasma.

What is hypersthenuria?

SG > ~1.012; tubules concentrate urine above plasma SG; osmolality > plasma.

Name a common method to evaluate SG and a caveat.

Refractometer; needs species-specific scale and proper temperature calibration.

What is a common limitation of urine SG reagent strips in animals?

Developed for humans; less reliable in animals and can be affected by protein, lipids, ketones, or alkaline urine.

What is osmolality (mOsm/kg) and how is it measured?

Measure solute concentration; most representative method uses osmometers (expensive and time-consuming).

How can USG roughly approximate urine osmolality?

Multiply the last two digits of USG by 36 (e.g., 1.030 ≈ 1080 mOsm/kg).

What are the primary SG evaluation tools?

Refractometer, urinometer, SG reagent strips, and osmometry.

What is the UPC ratio?

Urine protein-to-creatinine ratio; reflects 24-hour protein excretion from a single sample.

What are ketone bodies?

Acetone, acetoacetic acid, and β-hydroxybutyric acid; produced during fat metabolism and can cause ketonuria.

What does bilirubinuria indicate?

Presence of conjugated bilirubin in urine; can indicate biliary obstruction, hepatic disease, or other conditions.

What does urobilinogen in urine reflect?

Breakdown product of bilirubin by intestinal bacteria; elevated levels may indicate liver or GI tract dysfunction or intravascular hemolysis (though interpretation in animals is variable).

What is nitrite testing in humans used for?

Indirect indication of bacteriuria; in animals, urine cultures and microscopy are best for detecting bacteriuria.

What is leukocyte esterase testing reliability in cats vs dogs?

False positives are more common in cats; false negatives can occur in dogs; fresh urine microscopic evaluation is recommended.

What is the urobilinogen test’s usefulness in animals?

Unreliable or questionable in many veterinary patients; not routinely used as a definitive indicator.

What is the role of microscopic evaluation of urine sediment?

Provides exfoliate cytology; essential alongside physical/chemical tests to interpret turbidity, crystals, casts, and cells.

What sample preparation steps are recommended for urine sediment?

Best after extended rest; refrigerate if not examined within 20–30 minutes; centrifuge at manufacturer-recommended speed.

What should be done with the volume of sediment?

Note sediment volume; resuspend the sediment and use a small drop on a slide for examination.

Which staining approaches are used for urine sediment?

Stained (e.g., Sternheimer–Malbin, new methylene blue, Diff-Quik) or unstained; staining choice affects element appearance.

What is hyaline cast?

A few may be seen in normal urine; composed of mucoprotein; indicates mild renal irritation.

What do granular casts indicate?

Typically associated with acute nephritis or tubular degeneration; contain degenerated cells or proteins.

What do RBC casts signify?

Bleeding into the renal tubules.

What do WBC casts indicate?

Tubular inflammation or tubulointerstitial nephritis.

What are common types of crystals seen in urine and their associations?

Struvite (coffin lids) in alkaline urine or urease-producing infections; calcium oxalate; calcium carbonate; uric acid; leucine, tyrosine, cystine in acidic urine; ammonium biurate in certain breeds.

What animals commonly have calcium carbonate crystals in urine?

Horses and some ruminants; may form crystals in standing urine.

What is the typical common feline and canine urolith predominance historically?

Cats: calcium oxalate; dogs: struvite more common historically.

What is the general purpose of hematology testing in veterinary medicine?

Complete blood count (CBC) to evaluate red cells, white cells, platelets, and blood indices; assess overall health and detect disease.

What does a CBC typically include?

Total erythrocyte count, leukocyte counts, PCV (hematocrit), total plasma protein, hemoglobin, RBC indices, and blood film evaluation.

What does PLT stand for in hematology?

Platelets in peripheral blood.

What does PCT stand for in hematology?

Plateletcrit; a platelet index reflecting the relative volume of platelets in blood.

Why is NRBC correction sometimes necessary in WBC counts?

NRBCs can inflate the leukocyte count; correction is needed for accurate WBC estimates.

What anticoagulant is preferred for hematology in most mammals?

EDTA, in proper anticoagulant-to-blood ratio.

What anticoagulant is preferred for birds and reptiles?

Heparin.

What is the recommended practice for filling EDTA tubes?

Fill to at least 90% to maintain proper anticoagulant-to-blood ratio.

What happens if you over- or under-fill an anticoagulated tube?

Overfilling can cause cell distortion; underfilling can cause crenation and leukocyte changes.

Why should EDTA not be considered a preservative for hematology?

It prevents coagulation but does not preserve cellular morphology; samples should be processed promptly.

How should blood be transferred from syringe to vacuum tube?

Option A: remove stopper and needle; push blood to tube to preserve morphology; Option B: allow vacuum to pull blood after inserting syringe through stopper.

How should blood samples be mixed after collection?

Gently invert; do not shake.

What factors can cause stress leukograms in patients?

Fear, excitement, restraint; shift to mature neutrophilia, monocytosis, lymphopenia, eosinopenia in cats and dogs.

What are reticulocytes and how are they evaluated?

Immature erythrocytes with residual ribosomes; evaluated with Wright’s stain; aggregate and punctate forms in cats; aggregate is counted.

How is reticulocyte percentage reported?

As a percentage of RBCs or as an absolute reticulocyte count per microliter.

What is MCV?

Mean corpuscular volume; average size of erythrocytes; calculated from PCV and RBC count.

What is MCH?

Mean corpuscular hemoglobin; mean weight of Hb per RBC; calculated from Hb and RBC count.

What is MCHC?

Mean corpuscular hemoglobin concentration; proportion of Hb in the average RBC; calculated from Hb and PCV.

What does RDW measure?

Red cell distribution width; variation in RBC size; higher values indicate greater anisocytosis.

What is the significance of reticulocytosis?

Indicates bone marrow response to anemia; species variations exist (notably in horses).

What are platelets and how do MPV values relate to them?

Platelets are anuclear cytoplasmic fragments; MPV indicates average platelet size; higher MPV suggests younger/giant platelets; lower MPV suggests microplatelets.

What influences total plasma protein (TPP) measurements?

Hydration status; high in dehydration or inflammation; low with protein loss or hemodilution.

Why is quality control important for hematology instruments?

To ensure accuracy and reliability; include calibration, known controls, and instrument maintenance.

What special considerations apply to avian and reptilian leukocytes?

NRBCs are normal; counting is more difficult with standard mammalian methods; laser flow cytometry is increasingly used.