Urinalysis PDF

CLINICAL PATHOLOGY II – Lecture Urinalysis Components and What We Are Testing For & General UA information A. Why Do a UA? Aid in diagnosis: Diabetes, UTI, chronic renal failure before...

CLINICAL PATHOLOGY II – Lecture Urinalysis Components and What We Are Testing For & General UA information A. Why Do a UA? Aid in diagnosis: Diabetes, UTI, chronic renal failure before know Screen for disease: Presurgical, congenital, working a clinical/subclinical giving kidneys are Monitor progression of disease: Chronic renal failure (CRF) Evaluate therapy: Insulin tx; nephrotoxic agents antifreeze B. Components of a Urinalysis Gross Exam: Color, clarity, volume and odor Chemical Analysis: Dissolved substances Microscopic Exam: Formed elements C. Taking a history from clients is time well spent; CVT must ask non-leading and specific questions... Any changes in water consumption? Any changes in urine output? Any changes in bladder habits? Day vs night? Alert vs resting? Straining? Dribbling? Pain? Housetraining? Any changes in gross appearance? Color? Transparency? Blood? Urine Collection Methods (See Week #1 lab notes) Urinalysis I Urinalysis – The Gross Exam A. Volume: Normal urine production is known but difficult to measure 1 to 2 ml/kg/hour on normotensive, normovolemic patient with intact renal function. o Example: 62# dog should produce 675 to 1350 ml in 24 hours o Closed system may be attached to urinary catheter to monitor volume. o Metabolic cages are easier to use to monitor volume than closed system, but are probably not available to most clinics. that collect & specific cages urine output Influences on Urine Volume o Water intake o Environmental temperature o Food intake o Level of physical activity o Species of animal animalscommonlimates  Urine Volume & Specific Gravity (SG) o High volume has low SG (dilute) o Low volume has high SG (concentrated) Polyuria (PU) is the increase in urine volume (as measured over 24-hour period) o Normal and appropriate = Physiologic functioning normally o Abnormal and inappropriate = Pathologic Disease > o Polyuria generally produces pale urine with low specific gravity o Polyuria is not pollakiuria which is frequent urination, but total 24-hour volume is WNL Physiologic PU ▪ Increased fluid consumption ▪ Diuretic therapy fluid ▪ Fluid administration canimalsmore on therapy ▪ Corticosteroid therapy urinate Pathologic PU pancreas doesnt send insulin ▪ Diabetes mellitus Diluting glucose inblood antidiruetic ▪ Diabetes insipidus thyroid isn't sending ▪ Renal failure uterus ▪ Pyometra concentration of pug in ▪ Liver disease much ▪ Cushings disease kidneys producing too · corticosteroida Oliguria is the decrease in urine volume and can be either physiological or pathological. o Generally produces dark urine with high specific gravity Physiologic Oliguria ▪ Decreased fluid intake ▪ Mild dehydration as a result of normal bodily function such as panting or sweating Pathologic Oliguria ▪ Dehydration ▪ Cardiac disease blood is not going to kidneys ▪ Renal failure ▪ Shock Anuria is the complete lack of urine production o Always pathologic o Most often result of ⋅ Urethral obstruction or bladder rupture ⋅ “End stage” renal failure B. Color: Normal color is pale yellow to amber, due to the presence of urochromes, which is a by-product of Hb metabolism. Colorless urine corresponds to polyuria and low SG  Yellowish-brown or greenish-brown is associated with bile pigments in urine (Bilirubinuria). o Yellowish-brown urine will often produce a greenish-yellow foam when shaken Red or reddish-brown indicates the presence of RBCs (hematuria) or hemoglobin (hemoglobinuria). o Hematuria: RBCs will be spun to bottom of tube, leaving supernatant clear of red color and RBCs will be seen on microscopic examination o Hemoglobinuria: Free Hb remains suspended in supernatant, leaving supernatant red and RBCs are not visible on microscopic examination (or only few are observed). Brownish-black indicates presence of myoglobin in urine; Mb remains suspended in supernatant, leaving supernatant brownish-black. May be caused by: o Exertional rhabdomyolysis o Electrical shock o Seizures o May be normal in equine urine if urine has been allowed to sit C. Transparency: Influenced by presence or absence of “formed elements” Tranparent urine indicates less particulate matter in the urine (normal for most species) Hazy or slightly cloudy indicates slighltly more particulate matter and can be normal Turbid or cloudy indicates more formed elements in it such as crystals, bacteria, cells, or mucus. Normal in certain species such as o Horses o Rabbits o Guinea pigs o Some reptiles o Birds Flocculent urine contains contains chunks or flakes of suspended matter. Lack of transparency caused by presence of formed elements o RBCs o WBCs o Crystals o Epithelial cells o Mucus o Fat o Casts o Bacteria Normal, clear urine can become cloudy if allowed to sit due to bacterial growth and crystal formation or contamination from lower urinary tract secretions D. Odor Strong: Normal in males, especially cats, goats and pigs Ammonia: In fresh urine, can indicate bacterial cystitis with urea-splitting organisms Sweet and/or fruity: Presence of ketones E. Foam  Slight amount of white foam is normal Proteinuria: Excessive foam that is slow to dissipate Bilirubinuria: Greenish-yellow foam F. Specific Gravity= Weight of liqiud compared to an equal volume of distilled water SG is determined by number and size of dissolved solutes (particles) Measured by o Refractometer: Ability of fluid to bend light correlates with density (most accurate) o Urinometer: More dense the fluid, higher the float will be suspended in fluid (less accurate method) Normal range for most domestic species is 1.015 – 1.045 SG reflects ability of kidneys to concentrate or dilute urine Isosthenuria= when urine SG is similar to plasma and is not more concentrated or more dilute. ▪ SG = 1.008 – 1.012 ▪ Indicates that kidneys are unable to concentrate or dilute urine ▪ Frequently associated with renal disease ▪ Even when deprived of water, SG will remain in range of 1.008 to 1.012 Increased Urine SG ▪ Dehydration ⋅ Fever ⋅ Shock ⋅ Vomiting and/or diarrhea ⋅ Warm weather ⋅ Decreased water consumption ▪ Increased urine solutes ⋅ Protein (including Hb and Mb) ⋅ Glucose Decreased Urine SG ▪ Renal failure ▪ Liver disease ▪ Diabetes mellitus  ▪ Diabetes insipidus ▪ Pyometra ▪ Cushings disease ▪ Fluid tx ▪ Corticosteroid tx ▪ Diuretic tx Urinalysis: Chemical Components A. Reagent Strips The chemical exam for a urinalysis is typically done on a reagent strip with different pads for each chemical component it is testing. Different reagents strips can be purchased with different amounts of pads on each strip Proper storage / handling of dipsticks are crucial for accurate results o Keep container tightly closed o Keep dipsticks dry o Monitor expiration date: Do not use expired dipsticks B. Individual Tests on Reagent Strips pH =Degree of acidity or alkalinity of urine largely dependent upon diet o High protein diet = Acidic urine (carnivores) o Plant-based diet = Alkaline urine (herbivores) o Normal values for urine pH more in alkaline urine ▪ Dog and cat: ~ 5.5 - 7.5 ▪ Horse: ~ 8 Certaincrystak is for ▪ Cow, sheep, and goat: ~ 7.4 - 8.4 o Decreased pH (i.e., acidic): Fever, starvation, excessive muscular activity, certain medications, high-protein diet o Increased pH (i.e., alkaline or basic): UTI, urine retention, certain medications Protein: Proteinuria o Always interpret proteinuria (and any other substance or element) in association with So urine SG: -okay more protein-high o Protein in urine with high SG is less serious than same protein level in urine with low SG o Proteinuria with low SG means that more protein is being lost low SG wh high protein o Very dilute urine can result in false negative for protein means proteins are from being blood pulled  Physiologic Proteinuria ▪ Very small amounts can be normal ▪ Strenuous exercise: Training, racing ▪ Neonatal animals: First few days of life ▪ Ingestion of excessive amounts of protein ▪ Estrus ▪ Emotional stress in humans and may also occur in animals Pathologic Proteinuria o Pre-renal: Due to non-renal conditions of blood ▪ Hemoglobinuria: Intravascular hemolysis break down in · veing ▪ Myoglobinuria: Excessive damage to muscle o Renal: Due to increased permeability of glomerulus OR impaired reabsorption of protein by renal tubules ▪ Glomerulonephritis ▪ Pyelonephritis ▪ Renal neoplasia tumor " ▪ Chemical poisoning: Arsenic, lead, mercury ▪ Immune disease o Post-renal: Protein enters urine after urine leaves kidneys via contamination with exudates or blood ▪ Inflammation of ureter(s), bladder, or genitals; prostatitis, ureteritis, urethritis, cystitis, vaginitis ▪ Hemorrhage in urogenital tract (RBCs contain protein): Catheterization, manual expression, blow to abdomen should not come out in urine Glucose: Glucosuria or glycosuria o Only occurs in healthy animals if BG level exceeds renal threshold ▪ ~ 180mg/dL in dogs ▪ ~ 250mg/dL in cats (you’ll see different published ranges here; typically between 240mg/dL and 280mg/dL) ▪ ~ 100mg/dL in horses and ruminants o Dependent upon ▪ Blood glucose levels: Hyperglycemia ▪ Rate of glomerular filtration ▪ Rate of tubular reabsorption - high Sugar Physiologic Hyperglycemic Glucosuria ▪ Fear, excitement, or restraint (especially in cats) ▪ Heavy exercise; “fight-or-flight” response Stress ▪ Administration of epinephrine ▪ High-carbohydrate meal  ▪ IV fluids containing glucose ▪ Occasionally following general anesthesia Pathologic Hyperglycemic Glucosuria ▪ Diabetes mellitus can't produce ▪ Acute pancreatic necrosis > - ingui ▪ Increased intracranial pressure ▪ And sometimes in: hyperthyroidism, cushings disease, & chronic liver disease Non-hyperglycemic Glucosuria or Renal glucosuria: ▪ Reduced reabsorption in renal tubules which permits glucose to spill into urine ▪ Lowered renal threshold for glucose False-Positive Glucosuria ▪ Vitamin C ▪ Aspirin ▪ Morphine ▪ Lactose ▪ Some antibiotics ⋅ Cephalosporins ⋅ Penicillin ⋅ Streptomycin ⋅ Chloramphenicol ⋅ Terramycin ⋅ Oxytetracycline Nitrite: Positive nitrite test in fresh urine indicates bacteriuria o Certain gram-negative bacteria contain nitrate-reducing enzymes: E. coli, Proteus spp. and Klebsiella spp. o To detect nitrate-reducing bacteria ▪ Diet must contain nitrate most Vegetables AND ▪ Urine must be retained in bladder long enough for bacterial enzymes to convert nitrate to nitrite (at least four hours) ▪ Most animals with a UTI urinate frequently, so a negative nitrite test does NOT mean these bacteria are absent only way to determine of there is bacteria is Microscopic analysis Ketones: Ketonuria= Ketone bodies present in urine (Acetone, Aceto-acetic acid, and Beta- hydroxybutyric acid) contains lotofogen a makes #t to acidic  o Ketones are by-product of incomplete fatty acid metabolism and are caused by: ▪ Decreased carbohydrate intake ⋅ High-fat, low carbohydrate dietmost energya carbohydrates carb det fat metabolism ⋅ Starvation, fasting, long-term anorexia low = ▪ Defects in carbohydrate metabolism; e.g., diabetes mellitus ▪ Impaired liver function o Some ketone bodies can contribute Hydrogen ions to the bloodstream and can lead to ketoacidosis o Kidneys excrete this excess H+ to reestablish homeostasis making urine pH more acidic Bilirubin (A Bile Pigment): Bilirubinuria o Bilirubin is a by-product of RBC breakdown o Normally conjugated in liver and excreted by way of bile duct to gallbladder to intestines o Bilirubin is light-sensitive, and will break down when exposed to light o Dogs (especially males) and cattle may have normal trace amounts due to low renal threshold for bilirubin Jaundice appearance abnormal in Sheep norges Prehepatic: cate ▪ Increased breakdown of RBC (hemolytic anemia) Hepatic ▪ Viral hepatitis ▪ Toxic hepatitis ▪ Cirrhosis Posthepatic ▪ Obstruction of bile duct ▪ Gallstones ▪ Cancer Urobilinogen: Also a Bile Pigment o Conjugated bilirubin is converted to urobilinogen in the intestines, then some is reabsorbed into bloodstream; a small amount urobilinogen in urine is normal o Urobilinogen will be elevated with ▪ Increased breakdown of RBCs ▪ Liver disease ▪ Stasis of bowel bowels stop working o Urine sample must be fresh and remain unexposed to light in order to detect urobilinogen o Due to instability of urobilinogen, urine screening tests are unreliable Blood: Hematuria o Blood pad on dipstick will react to RBCs, hemoglobin and myoglobin o Must examine microscopically o 0 – 1 RBC/hpf is considered normal o “Occult” blood = Hidden blood not observed grossly on urine examination Hematuria  ▪ Can be gross or microscopic (“occult”) ⋅ Plasma / serum will appear normal in color ⋅ Urine supernatant color will be WNL ⋅ Will see intact RBCs in sediment ▪ Causes ⋅ Cystitis ⋅ Trauma ⋅ Calculi ⋅ Neoplasia ⋅ Iatrogenic Clinic in causes ⋅ Anticoagulants Hemoglobinuria ▪ Result of free Hb in plasma/serum ⋅ Plasma / serum will be pink or red ⋅ Urine supernatant will be pink or red ⋅ Hemoglobin is not visible on microscopic exam ▪ Result of increased RBC destruction; i.e., intravascular hemolysis ⋅ Hemolytic anemia ⋅ Toxic plants ⋅ Blood parasites ⋅ Bacterial and viral diseases ⋅ Transfusion reactions Myoglobinuria ▪ Myoglobin = Protein found in muscle; released into bloodstream with acute and severe muscle damage ⋅ Plasma / serum will appear normal in color ⋅ Urine supernatant will appear reddish or brown/black ⋅ Myoglobin is not visible on microscopic exam ▪ Causes ⋅ Exertional rhabdomyolysis ⋅ Trauma ⋅ Electrical shock ▪ Difficult to differentiate from Hb ⋅ May use 80% ammonium sulfate precipitation test: Hb precipitates and Mb  does not. ⋅ Serum/plasma will provide clue too ✓ Pink/red color if Hb is present ✓ WNL color if Mb is present Urinalysis: Formed Elements A. Epithelial Cells Squamous Epithelial Cells o Surface cells from distal urethra, vagina, vulva or prepuce o Frequently seen in voided urine; few might appear following catheterization; not normally observed following cystocentesis o Generally not significant, but always reported Transitional Epithelial Cells o Line the proximal urethra, bladder, ureters, and renal pelvis ▪ Increased numbers can be observed following catheterization ▪ Increased numbers suggest cystitis or pyelonephritis o Sheets or clumps can indicate neoplasia Renal Tubule Cells nucleus is round o Originate in renal tubules o Rarely found o Indicate renal tubular disease ▪ Increased numbers suggest disease of renal parenchyma B. Blood cells WBCs (Leukocytes) o Normal urine may have few WBCs: 0 to 1 WBC/hpf eak j o Neutrophils are most common bacteria o Increase with inflammation of urinary tract ▪ Pyelonephritis ▪ Cystitis ▪ And also with reproductive disorders o Pyuria = Excessive WBCs in urine and indicate ▪ Nephritis  ▪ Pyelonephritis ▪ Cystitis ▪ Urethritis ▪ Ureteritis RBCs (erythrocytes) o May observe 0 to 1 RBC/hpf in normal urine o Sampling technique can cause hematuria. o Proestrus, estrus, and postpartum o If “blood” pad is positive, look for RBCs on microscopic exam. No RBCs = hemoglobinuria or myoglobinuria o May be confused with fat, yeast and amorphous urate crystals crenate : concentrated urine spiky appearance Dilute urine Lyge : swollen C. Crystals: Crystalluria ✓ Very common ✓ Often not significant but may be sign of urolithiasis ✓ Must consider urine pH, concentration and temperature of sample ✓ Will increase in number and size if sample analysis is delayed and/or cooled 1. Struvite: Aka “magnesium ammonium phosphate” or “triple phosphate” Typically form in slightly alkaline urine, but may be found in neutral or slightly acidic urine. Commonly associated with stones in dogs and FLUTD (formerly known as “FUS’) in cats. o FLUTD = Feline lower urinary tract disease o FUS = Feline urological syndrome Prescription diets my help with decreasing struvite formation (ie. Hill’s Prescription Diet®: c/d). Decreased ash content minerals Modification of pH 2. Amorphous phosphates / urates Granular precipitate. Urates: Found in acidic urine. Phosphates: Found in alkaline urine. 3. Calcium oxalate dihydrate Found in acidic to slightly alkaline urine. Another common cause of FLUTD. Prescription diets may help reduce these crystals also. 4. Calcium carbonate Common in herbivores. Form in neutral to alkaline urine. One reason that rabbit, horse, goat, and cavy urine is cloudy. 5. Uric acid: Found in acidic urine. By product of digesting purines. Common in Dalmatians as they can not convert uric acid to allantoin. May also be found in English Bulldogs, but typically to a lesser extent than Dalmatians. 6. Cystine: cystinuria Found in acidic urine. Not a common finding in dogs or cats. Typically in dogs who tend to excrete cystine which is an amino acid (ie… patients with disorders of protein metabolism). 7. Calcium oxalate monohydrate: Acidic to slightly alkaline urine. Typically due to excess calcium and excess oxalates. May be seen “picket fence” form with ethylene glycol toxicity (antifreeze). May be seen in horse urine as normal. 8. Ammonium urates (sometimes called “ammonium biurates): Acidic to neutral urine. Potentially observed in severe liver disease. Very uncommon findings in most dogs and cat EXCEPT Dalmatians and English Bulldogs. 9. Bilirubin: Acidic urine. May be normally found in concentrated urine from dogs. If seen in felines, equines, bovines, and camelids, the liver must be evaluated for disease. 10. Leucine and tyrosine: Indicative of liver disease in humans. Not common in dogs and cats. 11. Sulfonamide: Drug related crystals formed in animals receiving sulfa drugs. Will change appearance dependent on pH and concentration of urine. D. Casts ✓ “Cylindruria” ✓ Formed inside lumen of renal tubules and collecting ducts; large numbers indicate tubular disease ✓ Must have fresh sample as they will deteriorate with time due to _________of sample ✓ A rare hyaline or granular cast can be WNL alkalinity ✓ More significant if SG is low 1. Hyaline Casts May observe 0 to 1/hpf in normal urine Composed of muco-protein matrix Indicate mildest form of renal inflammation very ghosty 2. Granular Casts May observe 0 to 1/hpf in normal urine Most common type of cast Hyaline cast with granules of degenerated renal cells and/or WBCs Indicate more severe renal inflammation than hyaline casts 3. Renal Cell Casts Contain renal tubule cells; sometimes referred to as “epithelial cell” casts May be difficult to distinguish from WBC casts and are then identified as “cellular” casts Frequently accompanied by granular casts Are observed in o Ethylene glycol toxicity o Acute nephritis 4. Leukocyte Casts Contain WBCs Often accompanied by free WBCs in urine Indicate inflammation in renal tubules 5. Erythrocyte Casts Contain RBCs Frequently accompanied by free RBCs Indicates hemorrhage within nephron 6. Waxy Casts Indicate chronic, severe kidney disease with decreased GFR 7. Fatty Casts  Cats normally have some fatty globules in their urine BUT should not have fatty casts unless renal tubules are diseased Dogs with diabetes mellitus often produce fatty casts Large number suggests degeneration of renal tubules & E. Other Formed Elements 1. Mucus Normal in horses like If present in other species, indicates -look threade o Genital contamination prepuce > - or o Irritation of urethra vulva 2. Sperm Common in the urine of intact males, recently neutered males, and recently bred females No clinical significance -- Do we report it? ↳ cryptorchid ↳ yes 3. Fat: Lipuria perfect circleso Normal in many cats y differentto > - Usually insignificant and can be contaminant from lubricant ↳ catheterization 4. Bacteria: Bacteriuria Only significant in catheter and cysto samples – Do we report it? If infection is present, will also see WBCs and/or RBCs Bladder most common site of infection. 5. Yeast Rare in veterinary patients colorless , round to oval budding 6. Fungi Rare, but very serious when it occurs Usually contaminant from outside body Distincthyphaeflamentaunsegmented 7. Parasites Urinary organ parasites o Dioctophyma renale: “Giant kidney worm” ▪ Largest nematode: Up to 3 feet in length ▪ Unaffected kidney will hypertrophy ▪ Tx = surgical removal of Kidney > - o Pearsonema (Capillaria) plica: ▪ Bladder worm of dog, cat and fox. ▪ Tx = ivermectin Fecal or genital contamination  o Tritrichomonas foetus: From prepuce o Various intestinal parasites – how? parasites in fecal contaminating volva 12/13/2024 3 Artifacts · pollen · leaf fragments · stain precipitate · air bubbles · all droplets · Hair · fecal droplets · plant spores · Duck · starch granules