lp 16 urinary system & urinalysis 2008

Urinary System & Urinalysis

VTT 250 Anatomy & Pathology LabVTT 250 Anatomy & Pathology Lab

StructuresKidneysKidneys

UretersUreters

BladderBladder

UrethraUrethra

Kidneys

FunctionProduction of urine which is the fluid that Production of urine which is the fluid that facilitates the elimination of metabolic facilitates the elimination of metabolic waste materials from the body.waste materials from the body.

Helps maintain homeostasis by Helps maintain homeostasis by manipulating the composition of blood manipulating the composition of blood plasma.plasma.

Regulation of the acid-base balance and Regulation of the acid-base balance and fluid electrolyte balance.fluid electrolyte balance.

Blood filtration, reabsorption, and Blood filtration, reabsorption, and secretion.secretion.

Function…Fluid Balance Regulation-Fluid Balance Regulation-

The amount of urine produced helps ensure The amount of urine produced helps ensure that the body contains the right amount of that the body contains the right amount of water.water.

If the body has excess water and needs to get If the body has excess water and needs to get rid of it, more urine is formed (rid of it, more urine is formed (diuresisdiuresis).).

If the body needs to conserve water, less If the body needs to conserve water, less urine will be produced.urine will be produced.

Much of this function is under the control of Much of this function is under the control of antidiuretic hormoneantidiuretic hormone (ADH) and (ADH) and aldosteronealdosterone..

Function…Acid-Base Balance Regulation-Acid-Base Balance Regulation-

Enabled by the ability to remove Enabled by the ability to remove hydrogenhydrogen and and bicarbonate ionsbicarbonate ions from the blood and excrete them from the blood and excrete them in the urine.in the urine.

Hormone Production-Hormone Production-The kidneys have a close association with the The kidneys have a close association with the endocrine system.endocrine system.They can influence the rate of release of ADH and They can influence the rate of release of ADH and aldosterone.aldosterone.They also produce They also produce erythropoietinerythropoietin and some and some prostaglandinsprostaglandins..

Gross AnatomyBean shaped and Bean shaped and covered by a fibrous covered by a fibrous capsule.capsule.

The indented area is The indented area is called a called a hilushilus..

Renal pelvis-Renal pelvis- a a urine collection urine collection chamber that forms chamber that forms the beginning of the the beginning of the ureterureter

Gross AnatomyRenal cortex-Renal cortex- outer outer portion.portion.

Renal medulla-Renal medulla- surrounds the renal surrounds the renal pelvis and has a pelvis and has a smooth appearance.smooth appearance.

Microscopic AnatomyThe Nephron-The Nephron-

The basic functional The basic functional unit of the kidney.unit of the kidney.

Each nephron is Each nephron is composed of a:composed of a:

Renal corpuscleRenal corpuscle

Proximal Convoluted Proximal Convoluted Tubule (PCT)Tubule (PCT)

Loop of HenleLoop of Henle

Distal Convoluted Distal Convoluted Tubule (DCT)Tubule (DCT)

Terms to Remember…

OsmosisOsmosis- the passage of water across a semi-- the passage of water across a semi-permeable membrane from a weaker to a permeable membrane from a weaker to a stronger solution.stronger solution.DiffusionDiffusion- the passage of a substance from an - the passage of a substance from an area of high concentration to an area of low area of high concentration to an area of low concentration.concentration.ReabsorptionReabsorption- the passage of chemical - the passage of chemical substances from the lumen of the renal substances from the lumen of the renal tubules into the renal capillaries, back into the tubules into the renal capillaries, back into the body.body.SecretionSecretion- the passage of chemical - the passage of chemical substances from the renal capillaries into the substances from the renal capillaries into the lumen of the renal tubules, out of the body, lumen of the renal tubules, out of the body, into the urine.into the urine.

Microscopic Anatomy…

Renal corpuscle-Renal corpuscle- located in the cortex located in the cortex of the kidney.of the kidney.

Made up of the Made up of the glomerulusglomerulus (a tuft of (a tuft of capillaries) and capillaries) and Bowman’s capsuleBowman’s capsule..The function is to filter blood in the first The function is to filter blood in the first stage of urine production.stage of urine production.The blood pressure within each glomerulus The blood pressure within each glomerulus is high because the blood comes directly is high because the blood comes directly from the renal artery and the aorta.from the renal artery and the aorta.The walls of the efferent arteriole of the The walls of the efferent arteriole of the glomerulus are able to constrict under the glomerulus are able to constrict under the influence of influence of reninrenin..

Microscopic Anatomy…

High pressure forces fluid and small High pressure forces fluid and small molecules out through the pores and molecules out through the pores and into the lumen of the glomerular into the lumen of the glomerular capsule.capsule.

This process of This process of ultrafiltrationultrafiltration results in results in the formation of the formation of glomerular filtrateglomerular filtrate..

It is very dilute and consists of 99% It is very dilute and consists of 99% water and 1% chemical solutes and is water and 1% chemical solutes and is isotonic with plasma.isotonic with plasma.

Microscopic Anatomy…

PCTPCT- a continuation of Bowman’s - a continuation of Bowman’s capsule.capsule.

The The longest part of the nephronlongest part of the nephron..

Functions-Functions-Reabsorption of glucose, water, and sodium from Reabsorption of glucose, water, and sodium from the filtrate.the filtrate.

Secretion of toxins and certain drugs (penicillin).Secretion of toxins and certain drugs (penicillin).

Concentration of nitrogenous waste- mainly urea Concentration of nitrogenous waste- mainly urea produced as a result of protein metabolism.produced as a result of protein metabolism.

Microscopic Anatomy…

Loop of Henle-Loop of Henle-FunctionFunction: to concentrate or dilute the : to concentrate or dilute the filtrate according to the status of the blood filtrate according to the status of the blood plasma and the rest of the extracellular plasma and the rest of the extracellular fluid.fluid.Occurs in 2 stages:Occurs in 2 stages:

Descending loop-Descending loop- water is drawn out of the water is drawn out of the filtrate by sodium ions and is reabsorbed by the filtrate by sodium ions and is reabsorbed by the capillaries.capillaries.Ascending loop-Ascending loop- sodium is pumped out of the sodium is pumped out of the filtrate into the medullary tissue.filtrate into the medullary tissue.

Microscopic Anatomy…Loop of Henle…Loop of Henle…

NaNa++ and Cl and Cl-- are pumped out of the ascending are pumped out of the ascending loop into the tissue of the surrounding medulla.loop into the tissue of the surrounding medulla.Normally, water would follow NaNormally, water would follow Na++ by osmosis by osmosis but the walls of the ascending loop are but the walls of the ascending loop are impermeable to water so this does not occur.impermeable to water so this does not occur.The walls of the descending loop are The walls of the descending loop are permeable to water, so water is drawn out by permeable to water, so water is drawn out by osmosis. osmosis.

Microscopic Anatomy…

The resulting filtrate, now referred to as The resulting filtrate, now referred to as urine, is more concentrated and is urine, is more concentrated and is reduced in volume.reduced in volume.

Microscopic Anatomy…

DCTDCT--FunctionFunction: to make final adjustments to the chemical : to make final adjustments to the chemical make-up of urine in response to the status of blood make-up of urine in response to the status of blood plasma.plasma.Under the control of Under the control of aldosteronealdosterone..

Reabsorption of sodium ions.Reabsorption of sodium ions.Excretion of potassium ions.Excretion of potassium ions.Regulation of the acid-base balance (pH) of the blood Regulation of the acid-base balance (pH) of the blood by the excretion of hydrogen ions.by the excretion of hydrogen ions.

In this part of the tubule, water is not reabsorbed in In this part of the tubule, water is not reabsorbed in any great quantity.any great quantity.

Microscopic Anatomy…

Collecting Ducts-Collecting Ducts-Carry tubular filtrate through the medulla Carry tubular filtrate through the medulla and eventually empty into the renal pelvis.and eventually empty into the renal pelvis.

FunctionFunction: make final adjustments to the : make final adjustments to the water content of urine.water content of urine.

This change occurs by altering the This change occurs by altering the permeability of the duct walls.permeability of the duct walls.

Under the control of Under the control of antidiuretic hormone antidiuretic hormone (ADH).(ADH).

Physiology…Reabsorption-Reabsorption-

The glomerular filtrate The glomerular filtrate contains the waste contains the waste products that need to products that need to be removed from the be removed from the body.body.That filtrate also That filtrate also contains substances contains substances found in plasma that found in plasma that need to be need to be reabsorbed to reabsorbed to maintain homeostasis.maintain homeostasis.

SodiumSodiumPotassiumPotassiumCalciumCalciumChlorideChlorideMagnesiumMagnesiumGlucoseGlucoseAmino acidsAmino acidsBicarbonateBicarbonateWaterWater

Physiology…Reabsorption-Reabsorption-

Some substances make this movement passively Some substances make this movement passively through through osmosisosmosis or or diffusiondiffusion..Others have to be actively transported across cell Others have to be actively transported across cell membranes.membranes.About 65% of all tubular reabsorption takes place in About 65% of all tubular reabsorption takes place in the PCT.the PCT.About 80% of the water, sodium, chloride, & About 80% of the water, sodium, chloride, & bicarbonate are reabsorbed.bicarbonate are reabsorbed.100% of the glucose and amino acids are 100% of the glucose and amino acids are reabsorbed.reabsorbed.

Glucose Threshold(p. 312)

The limit of the amount of glucose that The limit of the amount of glucose that can be reabsorbedcan be reabsorbed

Dogs: 180 mg/dlDogs: 180 mg/dl

Cats: 240 mg/mlCats: 240 mg/ml

Physiology…Secretion-Secretion-

Many waste products are not filtered from Many waste products are not filtered from the blood in sufficient amounts from the the blood in sufficient amounts from the glomerular capillaries.glomerular capillaries.

The “left over” substances are removed by The “left over” substances are removed by tubular secretion.tubular secretion.

Most tubular secretion occurs in the DCT.Most tubular secretion occurs in the DCT.

HydrogenHydrogen, , potassiumpotassium, & , & ammoniaammonia are are some of the substances eliminated by some of the substances eliminated by secretion.secretion.

Urine Volume Regulation

ADH & aldosterone are responsible for ADH & aldosterone are responsible for the majority of urine volume regulation.the majority of urine volume regulation.

Urine Volume Regulation

ADH acts on the DCT & collecting ducts to ADH acts on the DCT & collecting ducts to promote water reabsorption.promote water reabsorption.

Aldosterone increases the reabsorption of Aldosterone increases the reabsorption of sodium into the bloodstream.sodium into the bloodstream.

This causes an osmotic imbalance that This causes an osmotic imbalance that encourages water to follow sodium.encourages water to follow sodium.

Water cannot move out of the DCT unless Water cannot move out of the DCT unless sufficient ADH control is present.sufficient ADH control is present.

UretersThe tubes that exit the kidney at the The tubes that exit the kidney at the hilus and connect to the bladder.hilus and connect to the bladder.

They continuously move urine from the They continuously move urine from the kidneys to the bladder.kidneys to the bladder.

The smooth muscle layer propels the The smooth muscle layer propels the urine through the ureter by peristaltic urine through the ureter by peristaltic contractions.contractions.

BladderStores urine as it is produced and Stores urine as it is produced and releases it from the body.releases it from the body.

Lined with transitional epithelium that Lined with transitional epithelium that stretches as the bladder fills.stretches as the bladder fills.

The wall contains smooth muscle.The wall contains smooth muscle.When it contracts, urine is expelled.When it contracts, urine is expelled.

UrethraA continuation of the neck of the A continuation of the neck of the bladder that runs through the pelvic bladder that runs through the pelvic canal.canal.

Carries urine from the bladder to the Carries urine from the bladder to the external environment.external environment.

Pathology

Acute Renal FailureAn abrupt decrease in glomerular An abrupt decrease in glomerular filtration.filtration.

Usually the result of hypoperfusion or Usually the result of hypoperfusion or nephrotoxic injury to the kidney, which nephrotoxic injury to the kidney, which causes damage to the nephron.causes damage to the nephron.

Nephrotoxins- ethylene glycol, gentamicin, Nephrotoxins- ethylene glycol, gentamicin, sulfonamides…sulfonamides…

Azotemia-Azotemia- a build-up of toxins within a build-up of toxins within the body.the body.

Chronic Renal Failure

““CRF”CRF”A common disease of older pets.A common disease of older pets.An irreversible and progressive decline in renal An irreversible and progressive decline in renal function caused by destruction of the nephron function caused by destruction of the nephron units.units.Main coon, Abyssinian, Russian Blue, and Main coon, Abyssinian, Russian Blue, and Burmese breeds seem to be predisposed.Burmese breeds seem to be predisposed.Irreversible destruction of the nephron results Irreversible destruction of the nephron results in uremia.in uremia.BUN, BUN, Creatinine, & isothenuria specific Creatinine, & isothenuria specific gravity=watergravity=water

Ethylene Glycol Toxicity

Most dangerous form of antifreeze. Most dangerous form of antifreeze. Most commercial antifreeze products contain Most commercial antifreeze products contain between 95-97% ethylene glycol. between 95-97% ethylene glycol. Minimum lethal dose of undiluted ethylene Minimum lethal dose of undiluted ethylene glycol antifreeze is 4.4-6.6ml/kg in dogs and glycol antifreeze is 4.4-6.6ml/kg in dogs and 1.4ml/kg in cats. 1.4ml/kg in cats. Causes metabolic acidosis and acute renal Causes metabolic acidosis and acute renal tubular necrosis. tubular necrosis. Peak levels of ethylene glycol are reached Peak levels of ethylene glycol are reached within 1-4 hours post ingestion. within 1-4 hours post ingestion.

Ethylene Glycol Toxicity…

Clinical Signs: Clinical Signs:

Vomiting is seen within the first few Vomiting is seen within the first few hours progressing to depression, ataxia, hours progressing to depression, ataxia, weakness, tachypnea, polyuria, and weakness, tachypnea, polyuria, and polydipsia (1-6 hours) polydipsia (1-6 hours)

18-36 hours acute renal failure occurs. 18-36 hours acute renal failure occurs.

Diabetes Insipidus(p. 312)

Insipid means tasteless***Insipid means tasteless***

A decrease in the pituitary release of A decrease in the pituitary release of ADH (antidiuretic hormone)ADH (antidiuretic hormone)

ADH is responsible for regulating urine ADH is responsible for regulating urine volumevolume

The collecting ducts do not reabsorb The collecting ducts do not reabsorb adequate amounts of water which adequate amounts of water which causes PU/PDcauses PU/PD

FLUTD/FUS & Urolithiasis

Colville p. 317““Feline Lower Urinary Tract Disease” or “Feline Urologic Feline Lower Urinary Tract Disease” or “Feline Urologic Syndrome”Syndrome”Presence of mineral precipitatesPresence of mineral precipitatesUrolith’s are the most common causeUrolith’s are the most common causeCalcium oxylate is the most common mineral found Calcium oxylate is the most common mineral found (urine is too acidic)(urine is too acidic)Signs- hematuria, dysuriaSigns- hematuria, dysuriaDetected by urinalysis, radiographs or ultrasound.Detected by urinalysis, radiographs or ultrasound.Urolith’s that remain in the bladder can damage the Urolith’s that remain in the bladder can damage the bladder lining, resulting in secondary bacterial bladder lining, resulting in secondary bacterial infections and hematuria.infections and hematuria.

Different Types of Bladder Stones

(Urolith’s)

URINALYSIS

Physical PropertiesInclude all observations that can be Include all observations that can be made without the aid of a microscope or made without the aid of a microscope or chemical reagents.chemical reagents.

ColorNormal is light yellow to amber and is a Normal is light yellow to amber and is a result of pigments called result of pigments called urochromesurochromes..

The magnitude of color depends on the The magnitude of color depends on the degree of urine concentration or degree of urine concentration or dilution.dilution.

Color…ColorlessColorless- -

Low specific gravity.Low specific gravity.

Associated with Associated with polyuriapolyuria..

Dark yellow-Dark yellow- High specific gravity.High specific gravity.

Associated with Associated with oliguriaoliguria.(less urine than .(less urine than norm)norm)

Yellow-brown or green-Yellow-brown or green- is likely to is likely to contain bile pigments.contain bile pigments.

Color…Red or reddish-brown-Red or reddish-brown- indicates the indicates the presence of red cells (hematuria) or presence of red cells (hematuria) or hemoglobin (hemoglobinuria).hemoglobin (hemoglobinuria).

Brown-Brown- may contain myoglobin, which may contain myoglobin, which is excreted during conditions that cause is excreted during conditions that cause muscle cell lysis, such as muscle cell lysis, such as rhabdomyolysisrhabdomyolysis..

Clarity (Transparency)

Normal is clear/transparent.Normal is clear/transparent.

Urine may become cloudy while Urine may become cloudy while standing because of bacterial standing because of bacterial multiplication or crystal formation.multiplication or crystal formation.

OdorSamples standing at room temperature Samples standing at room temperature may develop an ammonia odor as a may develop an ammonia odor as a result of bacterial growth.result of bacterial growth.

Sweet or fruity odor indicates the Sweet or fruity odor indicates the presence of ketones.presence of ketones.

Urine Specific Gravity (USG)

Defined as the weight (density) of a liquid Defined as the weight (density) of a liquid compared to that of distilled water.compared to that of distilled water.

May be determined before or after May be determined before or after centrifugation.centrifugation.

USG yields information on the hydration status USG yields information on the hydration status and the ability of the kidney to concentrate or and the ability of the kidney to concentrate or dilute urine.dilute urine.

Only the refractometer should be used to Only the refractometer should be used to determine USG.determine USG.

Urine Specific Gravity (USG)…

Causes of Causes of USG- USG- water intakewater intake

fluid lossfluid loss

Acute renal failureAcute renal failure

DehydrationDehydration

ShockShock

Urine Specific Gravity (USG)…

Causes of Causes of USG- USG-Water re-absorption problemsWater re-absorption problems

fluid intakefluid intake

Excessive fluid administrationExcessive fluid administration

PyometraPyometra

Diabetes insipidusDiabetes insipidus

Diuretic therapyDiuretic therapy

Urine Specific Gravity (USG)…

Isothenuria “Fixed USG”-Isothenuria “Fixed USG”-1.008-1.0121.008-1.012

Occurs when the USG approaches that of Occurs when the USG approaches that of glomerular filtrate.glomerular filtrate.

Urine in this range has not been Urine in this range has not been concentrated or diluted by the kidneys.concentrated or diluted by the kidneys.

The closer the USG is to isothenuric, the The closer the USG is to isothenuric, the greater the amount of kidney function has greater the amount of kidney function has been lost (~75%).been lost (~75%).

CHEMICAL ANALYSIS

pHExpresses the hydrogen ion (HExpresses the hydrogen ion (H++) ) concentration.concentration.

A measure of the degree of acidity or alkalinity A measure of the degree of acidity or alkalinity of urine.of urine.

A pH >7.0 is alkaline, <7.0 is acidic.A pH >7.0 is alkaline, <7.0 is acidic.

Urine left standing open at room Urine left standing open at room temperature tends to increase in pH temperature tends to increase in pH resulting from a loss of carbon dioxide.resulting from a loss of carbon dioxide.

The pH of urine is largely dependant on diet.The pH of urine is largely dependant on diet.

pH…

Decreased pH-Decreased pH-Fever, starvation, high protein diet, acidosis, Fever, starvation, high protein diet, acidosis, excessive muscular activity.excessive muscular activity.

Increased pH-Increased pH-Alkalosis, high fiber diets, urethral obstruction, Alkalosis, high fiber diets, urethral obstruction, bladder paralysis (urine retention).bladder paralysis (urine retention).

An abnormal pH can result in crystal or urolith An abnormal pH can result in crystal or urolith formation.formation.The pH can be corrected by manipulating the The pH can be corrected by manipulating the diet to help dissolve the solids or prevent diet to help dissolve the solids or prevent uroliths from forming.uroliths from forming.

ProteinUsually absent or present in trace Usually absent or present in trace amounts of normal urine.amounts of normal urine.

Urine dip sticks allow semi-quantitative Urine dip sticks allow semi-quantitative measurements by progressive color measurements by progressive color changes on the reagent pad.changes on the reagent pad.

Reagent strips commonly detect Reagent strips commonly detect albuminalbumin and are not very sensitive to globulins and are not very sensitive to globulins (proteins insoluble in water). (proteins insoluble in water).

Protein…Urine Protein : Creatinine Ratio-Urine Protein : Creatinine Ratio-

This test is used to confirm significant This test is used to confirm significant amounts of protein in the urine.amounts of protein in the urine.

Used to determine the degree of protein Used to determine the degree of protein loss in chronic renal disease.loss in chronic renal disease.

See page 161See page 161

Protein…Protein interpretation-Protein interpretation-

Very dilute urine may yield a false negative Very dilute urine may yield a false negative because the protein concentration may be because the protein concentration may be below the sensitivity of the testing method.below the sensitivity of the testing method.Transient Proteinuria-Transient Proteinuria- may result from a may result from a temporary increase in glomerular permiability.temporary increase in glomerular permiability.

This condition is caused by increased pressure in the This condition is caused by increased pressure in the glomerular capillaries and may be found in muscle glomerular capillaries and may be found in muscle exertion, emotional stress, or convulsions. exertion, emotional stress, or convulsions.

Protein…Protein interpretation-Protein interpretation-

ProteinuriaProteinuria indicates disease of the urinary indicates disease of the urinary tract, especially the kidneys.tract, especially the kidneys.

Both acute and chronic renal disease lead to Both acute and chronic renal disease lead to proteinuria.proteinuria.

Acute nephritisAcute nephritis is characterized by is characterized by marked proteinuria with WBC’s and casts in marked proteinuria with WBC’s and casts in the urine.the urine.

GlucoseThe presence of glucose in the urine is known The presence of glucose in the urine is known as as glucosuriaglucosuria..Glucose is filtered through the glomerulus and Glucose is filtered through the glomerulus and reabsorbed by the tubules.reabsorbed by the tubules.Glucosuria usually does not occur unless the Glucosuria usually does not occur unless the blood glucose level exceeds the renal blood glucose level exceeds the renal threshold.threshold.At this concentration, tubular reabsorption At this concentration, tubular reabsorption cannot keep up with the glomerular filtration cannot keep up with the glomerular filtration of glucose, and glucose passes into the urine.of glucose, and glucose passes into the urine.

Glucose…Glucosuria occurs in diabetes mellitus Glucosuria occurs in diabetes mellitus as a result of a deficiency of insulin or as a result of a deficiency of insulin or an inability of insulin to function.an inability of insulin to function.

Transient glucosuria-Transient glucosuria- a release of a release of epinepherine causes glucose levels to epinepherine causes glucose levels to rise for energy.rise for energy.

Causes: fear, excitement, restraint.Causes: fear, excitement, restraint.

KetonesIncludes: acetone, acetoacetic acid, and Includes: acetone, acetoacetic acid, and ββ-hydroxybutyric acid.-hydroxybutyric acid.Ketone bodies are formed during Ketone bodies are formed during incomplete catabolism of fatty acids.incomplete catabolism of fatty acids.When fatty acid metabolism is not When fatty acid metabolism is not accompanied by sufficient carbohydrate accompanied by sufficient carbohydrate metabolism, excess ketones are present metabolism, excess ketones are present in the urine.in the urine.

A condition known as A condition known as ketonuriaketonuria..

Ketones…Ketonuria frequently occurs in animals with Ketonuria frequently occurs in animals with diabetes mellitus.diabetes mellitus.

Because the animal lacks the insulin necessary Because the animal lacks the insulin necessary for carbohydrate metabolism, fat is broken for carbohydrate metabolism, fat is broken down to meet the animal’s energy needs and down to meet the animal’s energy needs and excess ketones are excreted in the urine.excess ketones are excreted in the urine.

Ketones are toxic, causing CNS depression and Ketones are toxic, causing CNS depression and acidosis.acidosis.

Hence- ketoacidosis or acidosis resulting from Hence- ketoacidosis or acidosis resulting from ketonuria.ketonuria.

Ketones…Transient ketonuria- can occur with Transient ketonuria- can occur with starvation or prolonged anorexia.starvation or prolonged anorexia.

ketones can suggest diabetes ketones can suggest diabetes mellitus.mellitus.

Bile PigmentsBilirubin and urobilinogen.Bilirubin and urobilinogen.

Only conjugated (water soluble) Only conjugated (water soluble) bilirubin is found in urine.bilirubin is found in urine.

Bilirubinuria can be seen with bile duct Bilirubinuria can be seen with bile duct obstructions, liver disease, and obstructions, liver disease, and hemolytic anemia.hemolytic anemia.

Bile Pigments… Bilirubin (bilirubinuria) suggests:Bilirubin (bilirubinuria) suggests:

Excessive hemolysis of RBC’s.Excessive hemolysis of RBC’s.

Hepatobiliary obstructionHepatobiliary obstruction

Liver diseaseLiver disease

BloodTests for blood in the urine detect:Tests for blood in the urine detect:

HematuriaHematuria- usually a sign of disease - usually a sign of disease causing bleeding somewhere in the causing bleeding somewhere in the urogenital tract.urogenital tract.HemoglobinuriaHemoglobinuria- usually the result of - usually the result of intravascular hemolysis.intravascular hemolysis.MyoglobinuriaMyoglobinuria- -

Myoglobin is a protein found in muscle.Myoglobin is a protein found in muscle.Severe muscle damage causes myoglobin to leak Severe muscle damage causes myoglobin to leak from muscle cells into the blood.from muscle cells into the blood.

Blood…Causes of Causes of hematuriahematuria--

Inflammation (cystitis)Inflammation (cystitis)UrolithiasisUrolithiasisBladder tumors- transitional cell carcinomaBladder tumors- transitional cell carcinomaIatrogenic trauma- catheter placement, Iatrogenic trauma- catheter placement, cystocentesis.cystocentesis.

Causes of Causes of hemoglobinuriahemoglobinuria--Excessive lysis of RBC’s (hemoglobinemia)Excessive lysis of RBC’s (hemoglobinemia)IMHAIMHAMismatched blood transfusionMismatched blood transfusionRBC parasitesRBC parasites

Blood…Causes of Causes of myoglobinuriamyoglobinuria--

Muscle cell lysisMuscle cell lysis

Excessive exerciseExcessive exercise

Electrical shockElectrical shock

Heat strokeHeat stroke

Snake venomsSnake venoms

LeukocytesYou can believe a positive reaction but You can believe a positive reaction but never believe a negative reaction.never believe a negative reaction.Always examine the sediment for Always examine the sediment for confirmation.confirmation.Presence usually indicates a bacterial Presence usually indicates a bacterial infection in the urogenital tract.infection in the urogenital tract.A positive A positive nitratenitrate reaction occurs with reaction occurs with a large quantity of bacteria in the urine.a large quantity of bacteria in the urine.

Microscopic Examination of Urine

The 5 “C’s”The 5 “C’s”

Cells, Casts, Crystals, Critters, & Cells, Casts, Crystals, Critters, & CrapCrap

Page 165

CellsErythrocytesErythrocytes- may have - may have several different several different appearances depending appearances depending on the urine on the urine concentration, pH, and concentration, pH, and time elapsed between time elapsed between collection and collection and examination.examination.May be confused with fat May be confused with fat globules or yeast.globules or yeast.Indicates bleeding Indicates bleeding somewhere in the somewhere in the urogenital tract.urogenital tract.

Cells…LeukocytesLeukocytes--

Larger than RBC’s.Larger than RBC’s.Finding more than Finding more than 2-3/hpf indicates an 2-3/hpf indicates an inflammatory process in inflammatory process in the urogenital tract.the urogenital tract.PyuriaPyuria is indicative of is indicative of nephritis, cystitis, or nephritis, cystitis, or urethritis.urethritis.Urine with pyuria should Urine with pyuria should always be cultured for always be cultured for bacteria.bacteria.

Cells…Squamous Epithelial Squamous Epithelial Cells-Cells-

Their presence usually Their presence usually is not considered is not considered significant.significant.

They often have They often have straight edges and straight edges and distinct corners which distinct corners which sometimes curl or sometimes curl or fold.fold.

They contain a small, They contain a small, round nucleus.round nucleus.

Cells…Transitional Cells-Transitional Cells-

Come from the Come from the bladder, ureters, renal bladder, ureters, renal pelvis, and proximal pelvis, and proximal urethra.urethra.Usually round, may be Usually round, may be pear-shaped or pear-shaped or caudate.caudate.Small nucleus.Small nucleus.Increased numbers Increased numbers suggest cystitis or suggest cystitis or pyelonepheritis.pyelonepheritis.

Cells…Renal Epithelial Cells-Renal Epithelial Cells-

The smallest epithelial The smallest epithelial cells observed in urine.cells observed in urine.

Originate in the renal Originate in the renal tubules.tubules.

Often confused with Often confused with WBC’s.WBC’s.

Generally round with a Generally round with a large nucleus.large nucleus.

Increased numbers Increased numbers occur in diseases of the occur in diseases of the renal parenchyma.renal parenchyma.

CastsFormed in the lumen of the distal and Formed in the lumen of the distal and collecting tubules of the kidney.collecting tubules of the kidney.

Where the concentration and acidity of urine is the Where the concentration and acidity of urine is the greatest.greatest.

In the renal tubules, secreted protein In the renal tubules, secreted protein precipitates in acidic conditions and forms precipitates in acidic conditions and forms casts shaped like the tubules.casts shaped like the tubules.All casts are cylindrical structures, with parallel All casts are cylindrical structures, with parallel sides.sides.Their ends may be tapered or round.Their ends may be tapered or round.Casts dissolve in alkaline urine.Casts dissolve in alkaline urine.Larger numbers may indicate a lesion in the Larger numbers may indicate a lesion in the renal tubules.renal tubules.

Cast Formation

Casts…Hyaline Casts-Hyaline Casts-

Clear, colorless, and Clear, colorless, and somewhat transparent somewhat transparent structures.structures.

Composed only of Composed only of protein.protein.

Usually only identified in Usually only identified in dim light.dim light.

Numbers are increased Numbers are increased with renal irritation, with renal irritation, fever, poor renal fever, poor renal profusion, or general profusion, or general anesthesia.anesthesia.

Casts…Granular Casts-Granular Casts-

Hyaline casts Hyaline casts containing granules.containing granules.

Most common type of Most common type of cast.cast.

May be coarse or fine.May be coarse or fine.

Seen with acute Seen with acute nepheritis.nepheritis.

Casts…Leukocyte Casts-Leukocyte Casts-

The presence of The presence of leukocyte casts leukocyte casts indicates indicates inflammation in the inflammation in the renal tubules.renal tubules.

Casts…Erythrocyte Casts-Erythrocyte Casts-

Indicate renal Indicate renal bleeding.bleeding.

Casts…Waxy Casts-Waxy Casts-

Usually wider, with Usually wider, with square ends.square ends.

Highly refractile.Highly refractile.

Indicates chronic, Indicates chronic, severe degeneration severe degeneration of the renal tubules.of the renal tubules.

Casts…Fatty Casts-Fatty Casts-

Contain many small Contain many small droplets of fat that droplets of fat that appears as refractile appears as refractile bodies.bodies.

Frequently seen in cats Frequently seen in cats with renal disease with renal disease because they have lipid because they have lipid in their renal in their renal parenchyma.parenchyma.

Suggestive of Suggestive of degeneration of the degeneration of the renal tubules.renal tubules.

Crystals““Crystalluria”Crystalluria”

Some crystals form as a consequence of Some crystals form as a consequence of metabolic diseases.metabolic diseases.

Conditions that lead to crystal formation Conditions that lead to crystal formation (diet) may also cause formation of (diet) may also cause formation of urinary calculi.urinary calculi.

The type of crystal depends on the urine The type of crystal depends on the urine pH, concentration, and temperature.pH, concentration, and temperature.

Crystals…Triple Phosphate-Triple Phosphate-

Alkaline urine.Alkaline urine.

““Coffin lids”Coffin lids”

Crystals…Amorphous Amorphous phosphates-phosphates-

Found in alkaline Found in alkaline urine.urine.

Amorphous urates-Amorphous urates-Found in acidic urine.Found in acidic urine.

Crystals…Ammonium biurate-Ammonium biurate-

YellowYellow

Dumbbell or sheaves Dumbbell or sheaves of needles.of needles.

Spheres with spicules-Spheres with spicules-““Thorn apples”Thorn apples”

Crystals…Calcium Oxylate-Calcium Oxylate-

Acidic urine.Acidic urine.

Monohydrate-Monohydrate-““Picket fence”Picket fence”

Common in ethylene Common in ethylene glycol toxicity.glycol toxicity.

Dihydrate-Dihydrate-““Envelopes”Envelopes”

Crystals…Uric Acid-Uric Acid-

Acidic urine.Acidic urine.

Yellow or brown.Yellow or brown.

Normal in which Normal in which species?species?

DalmationsDalmations

Crystals…Leucine-Leucine-

Acidic urine.Acidic urine.

Yellow or brownYellow or brown

Highly refractiveHighly refractive

Crystals…Tyrosine-Tyrosine-

Acidic urineAcidic urine

Fine needles grouped Fine needles grouped in clusters.in clusters.

Bilirubin-Bilirubin-Acidic urine.Acidic urine.

Yellow needles.Yellow needles.

Crystals…Cystine-Cystine-

Acidic urineAcidic urine

Colorless and highly Colorless and highly refractive.refractive.

Hexagonal plates.Hexagonal plates.

Crystals…Calcium CarbonateCalcium Carbonate

“Critters”Capillaria plica- Capillaria plica- bladder worm of bladder worm of dogsdogs

DirofilariaDirofilaria

Dioctophyma renale- Dioctophyma renale- kidney worm of dogskidney worm of dogs

“Critters”Spermatozoa-Spermatozoa-

Presence of sperm Presence of sperm indicates that the indicates that the urine has been mixed urine has been mixed with semen.with semen.

Sperm may be found Sperm may be found in intact males when in intact males when urine is collected by urine is collected by cystocentesis.cystocentesis.

“Critters”…Bacteria-Bacteria-

Small and consistent Small and consistent in shape.in shape.

Rods or cocci.Rods or cocci.

Usually accompanied Usually accompanied by leukocytes.by leukocytes.

Beware of Beware of contamination!contamination!

“Critters”…Fungal Hyphae-Fungal Hyphae-

Colorless.Colorless.

Usually contaminants Usually contaminants of a urine sample.of a urine sample.

“Crap”Mucus Threads-Mucus Threads-

Long, narrow, wavy Long, narrow, wavy strands.strands.

Originate from Originate from mucous surfaces.mucous surfaces.

Normal in small Normal in small numbers.numbers.

Greatly increased with Greatly increased with irritation of any kind.irritation of any kind.

“Crap”

Serum Chemistries (Review)

BUN-BUN- evaluates the kidneys ability to evaluates the kidneys ability to remove urea from the blood.remove urea from the blood.

Creatinine-Creatinine- formed from creatine, formed from creatine, found in skeletal muscle, also evaluates found in skeletal muscle, also evaluates the kidneys filtering ability.the kidneys filtering ability.

Glucose-Glucose- useful to evaluate the renal useful to evaluate the renal threshold and diabetes.threshold and diabetes.

Electrolyte Assays (Review)

Sodium-Sodium- evaluates filtration and evaluates filtration and reabsorption.reabsorption.

Chloride-Chloride- evaluates water distribution evaluates water distribution and osmotic pressure.and osmotic pressure.

COCO22/Bicarbonate-/Bicarbonate- evaluates excretion evaluates excretion and reabsorption.and reabsorption.

Send Out Tests (Usually)

Urine Culture and Sensitivity (C&S)Urine Culture and Sensitivity (C&S)

Creatinine : Cortisol RatioCreatinine : Cortisol Ratio

Protein : Creatinine RatioProtein : Creatinine Ratio

The End!!