Hematology Urinalysis Slideset Flashcards
View of scales on Veterinary Refractometer. The reticle has two scales for read out of urine specific gravity, one for cats, the other for dogs/large animals. The third scale is calibrated for protein concentration of plasma or serum. Note the specific gravity scale is up to 1.060 on the veterinary refractometer compared to 1.035 on the standard refractometer.
Recommended loading procedure of refractometer. Keep cover plate closed to avoid damage to the measuring prism. Place a small amount of sample on the exposed portion of the prism, such that the liquid will be drawn into the space between the prism and the cover plate by capillary action. Use a soft cloth or soft tissue paper moistened with water, for wiping the prism and bottom surfaces of the cover plate after using.
Reagent strips for urine chemistries are firm plastic strips to which are affixed several separate reagent areas. (Ames Multistix Reagent strips are routinely used in LSU-SVM Clinical Pathology Lab. Other brands are available.) Completely immerse the dipstick in fresh, well-mixed, uncentrifuged urine. Remove quickly to avoid dissolving out reagents.
Hold dipstick horizontally and tap the edge of the stick on absorbent paper to remove excess urine so to prevent possible mixing of chemicals from adjacent reagents.
Visually compare test areas to corresponding color chart on the bottle label at the time specified. Proper reading time is critical for optimal results. Some colors may become more intense for a time and then fade. (See package insert for explanations and limitations of each chemical reaction.)
Differentiate WBC’s and RBC’s – RBC’s are smaller, may be concave or folded, crenated, uniform in size. WBC’s are larger, round to oval, have granular internal structure, may swell and/or lyze in very dilute or alkaline urine.
WBC’s and bacteria – all WBC’s, granular internal structure, loaded with bacteria. Consider age of sample-organisms multiply at room temps: be cautious of diagnosis of numerous bacteria are seen but no cells.
Fat droplets – Fat vs. RBC’s; fat droplets are round, refractile, and vary in size. They also float to top of coverslip so they are in different planes of focus. No clinical significance – see lots in cats. Fat droplets have an orange to red color when stained with Sudan III or Sudan IV, a bluish color when stained with Sedi-stain and appear colorless when stained with New Methylene Blue.
Squamous epithelial cells – Generally the largest cell seen in urine sediment. Usually have irregular outline and may contain a small, round nucleus. From the lower urinary tract and may appear in large numbers especially in voided urines.
Folded squamous epithelial cell – Maybe confused with casts.
Transitional Epithelial Cells – intermediate in size between a squamous epithelial cell and a WBC. Often granular cytoplasm and may contain a small nucleus. May see low numbers normally.
Formation of Casts – casts are cylindrical shaped structures composed primarily of Tamm-Horsfall mucoprotein formed in the distal and collecting tubules of the kidneys. Any cells or cellular debris present in tubules may get trapped in the formation of the casts giving rise to several different types of casts. Casts indicate varying degrees of renal changes.
Hyaline cast – 40x – Since the refractive index of hyaline casts are similar to urine, they appear as colorless, homogeneous, semitransparent, cylindrical structures. Have parallel sides, and usually rounded ends. Made of protein alone. Few may be normal in urine, but may indicate mildest form of renal irritation. Must lower condenser to see!!
Hyaline casts – 10x – can only be seen in well-darkened field. Can be easily missed if subdued light is not used.
Granular casts – hyaline cast containing granules with no distinct cell type. Most common type of cast seen in domestic animals. Represents the disintegration of renal tubular epithelium. Casts may vary in size slightly.
WBC cast – Sedi-stained prep – WBC’s adhere to the hyaline matrix. Presence of WBC casts is indicative of infection at the site of cast formation in the tubules. Differs from granular cast in that no disintegration of cells has occurred.
Fatty cast – Sedi-stained prep – highly refractile fat droplets adhere to the granular cast matrix. Commonly seen in cats with renal disease due to increased lipid content in urine.
Waxy cast – Sedi-stained prep – Broader than hyaline casts, highly refractive with broken waxy appearance and blunt ends. Indicates severe nephritis and renal degeneration.
Blastomyces – systemic mycotic agent. May appear similar to WBC but have thicker cell wall and usually budding. Only occasionally seen in urine in animals with renal infection.
Triple Phosphate (Struvite) crystals – commonly known as “coffin lids”. Most frequently seen crystals especially in normal dogs. Present in alkaline, neutral and slightly acid urine.
Calcium Oxalate crystals (dehydrate) – small, colorless envelopes (squares crossed by 2 intersecting diagonal lines). Normal in horses and few are O.K. in canine; however may be observed in association with ethylene glycol toxicity. Present in acid, neutral and slightly alkaline urine.
Calcium Oxalate crystals (monohydrate) – colorless, rectangular crystals with blunted points or “picket fence” appearance. Highly suggestive of ethylene glycol toxicity. Present in acid, neutral and slightly alkaline urine.
Calcium Carbonate crystals – radial striations or dumbbell forms. Present in alkaline urine and very common in horses.
Bilirubin crystals – yellow to reddish brown needle-like structures with center constriction. Usually goes along with a positive bilirubin reaction on the dipstick.
Ammonium Biurate crystals – yellow to brown in color and appears as spheres covered with spicules or sheaves of needles. Usually present in alkaline urine. Can be seen normally in Dalmatians; however, in other species, may be indicative of liver problems.
Cystine crystals – flat, colorless, hexagonal plates with well defined edges. May be seen singly or in clusters. Indicative of a rare metabolic problem.
Surgical starch powder (artifact) – normal contaminant in urine from gloves. Other contaminants are pollen grains, glass particles, fecal material, and fragments of cotton.
