Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
162 Cards in this Set
- Front
- Back
What is needed in order to identify common microscopic structures that can be found in urine sediment? |
-a fresh urine sample
|
|
Describe the Intact Nephron Hypothesis
|
-if the glomerulus gets destroyed, the entire nephron will die
-if the tubules get destroyed, the entire nephron will dies |
|
3 Major Physiological processes of the nephron
|
-Glomerular filtration (passive) |
|
What happens to water that is in tubules?
|
-the water that is present is from the glomerular ultrafiltrate
-most of this water is reabsorbed -NO water is added by tubular cells |
|
In a healthy person, how much water enters the tubules each day, compared to the amount of water that is excreted?
|
-180 L enters the tubules
-only 1-2 L excreted |
|
Glomerular Filtration Rate (GFR)
-definition |
-the rate that substances are cleared from the plasma through the glomerulus
|
|
What typically occurs when GFR decreases?
|
-substances in the blood are cleared slower causing their concentrations in the plasma to increase
-with decreased GFR there is a dec in excretion of metabolic waste through the kidneys |
|
Substances that normally pass through the glomerular filtration barrier
|
-water
-solutes/proteins smaller than albumin |
|
Why does tubular fluid become more dilute in the ascending loop of henle?
|
-solutes are being removed from the fluid
|
|
Animal that typically has the most concentrated urine (highest osmolality)?
-least concentrated urine |
-highest: cats
-lowest: cattle and horses |
|
Osmolality
-definition |
-total solute concentration
|
|
Solute osmolality that typically isn't increased in the urine compared to the plasma
|
-glucose
-the body tries to retain glucose |
|
Events in the proximal collecting tubule
|
No change in concentration due to removal of total volume
-water reabsorbed -solutes reabsorbed |
|
Events in the descending loop of henle
|
Increase in solute concentration
-water reabsorbed |
|
Events in the ascending loop of henle
|
Decrease in solute concentration
-removes solutes -water volume the same |
|
Events in the distal nephron
|
Concentration dependent on ADH activity
-increased concentration if water removed -remains dilute if water is not removed |
|
In order for the nephron to concentrate urine, what must occur?
|
-all parts of the tubule must be functional
|
|
Chronic renal insufficiency
-definition |
-when a chronic disease damages the kidneys to an extent that the renal tissue is no longer able to function and maintain health
|
|
Chronic renal insufficiency
-categories |
-diminished renal reserve
-chronic renal insufficiency -chronic renal failure -end-stage renal disease |
|
Diminished renal reserve
-characteristics |
-GFR = 50% normal
-animal is clinically healthy -no azotemia present |
|
Chronic renal insufficiency
-chracteristics |
-GFR = 20-50% normal
-azotemia and anemia -polyuria from a decreased concentration ability |
|
Chronic renal failure
-characteristics |
-GFR = < 20-25% normal
-azotemia and anemia -polyuria from a decreased ability to concentrate -inability for the kidneys to regulate extracellular fluid volume or electrolyte balance |
|
End-Stage Renal disease
-characteristics |
-GFR = < 5% normal
-termial stages of uremia present with oliguria or anuria |
|
How is a cats concentration ability different from other animals?
|
-most cats are still able to concentrate urine until about 85% functional renal loss
|
|
Acute Renal Insufficiency
-definition |
-reversible or irreversible renal dysfunction resulting abruptly from renal disease or an insult that markedly decreases the GFR and leads to azotemia
|
|
Azotemia
-defintion |
-increase in non-protein nitrogen compounds in the plasma (urea/creatinine)
|
|
Uremia
-defintion |
-increase in non-protein nitrogen compounds in the plasma with the presence of clinical signs reflecting renal failure
|
|
3 things to think about concerning azotemia
|
-prerenal azotemia
-renal azotemia -postrenal azotemia |
|
Relationship of Renal Plasma Flow and GFR
|
-blood must flow through the glomerulus in order for there to be plasma filtration
|
|
Possible paths of urea in the body
|
-produced by hepatocytes that convert NH4 (produced by either tissues or bacteria in the intestines) to urea
-pass through the glomerulus and enter renal ultrafiltrate -some reabsorption by renal tubules -excretion in urine -excretion in intestine/feces |
|
Possible paths of creatinine in the the body
|
-produced from creatine degredation in muscle fibers
-pass through flomerulus and enter renal ultrafiltrate -NO reabsorption by renal tubules -excretion in urine -excretion in intestines |
|
Causes of partial or complete urinary tract obstruction
|
-urolithiasis
-neoplasms -injuries |
|
Which substance will diffuse faster from extravascular fluid? urea or creatinine?
|
-urea
|
|
Prerenal Azotemia
-causes |
-hypovolemia
-shock |
|
Renal Azotemia
-causes |
Chronic:
-Inflammatory -Amyloidosis Acute: -Toxic nephrosis (hypercalcemia, ethylene glycol) -Renal iscemia/hypoxia |
|
Postrenal Azotemia
-causes |
-urinary tract obstruction
-leakage |
|
Decreased [UN]
-causes |
-decreased synthesis (hepatic insufficiency)
-increased renal excretion (impaired reabsorption by the proximal tubules) |
|
[UN] vs. [Crt]
|
-normally parallel eachother
-[Crt] more sensative to decreased GFR than [UN] in horses and ruminants |
|
[UN] is affected by:
|
-renal tubular reabsorption
-protein catabolism |
|
Although routine urinalysis components vary between labs, what should be the same in all of them?
|
-the use of fresh urine
|
|
Common components analyzed in urine
|
-physical (color, clarity, USG)
-chemical -sediment |
|
3 Factors that determine urine composition
|
-composition of the plasma that is presented to the kidneys
-renal function (filtration, reabsorption, secretion) -what is added during flow through the renal tubules and post-renally |
|
colorless urine
-meaning |
-dilute
|
|
light yellow urine
-meaning |
-normal
|
|
dark yellow urine
-meaning |
-normal/concentrated (urochromes)
|
|
Red & Clear urine
-meaning |
-hemoglobinuria/myoglobinuria
|
|
Red & Cloudy urine
-meaning |
-Hematuria
|
|
Orange to Brown urine
-meaning |
-Bilirubin
|
|
Coffee-brown urine
-meaning |
-myoglobinuria
-methemoglobinuria |
|
Clear urine
-meaning |
-expected
-any solutes are dissolved |
|
Hazy to Cloudy urine
-meaning |
-suspended particles are present (cells, crystals, etc.)
|
|
When is solute concentration in urine expected to change?
|
-inc. if kidneys are conserving water
-dec. if the kidneys are not conserving water |
|
How is solute concentration in urine measured?
|
-Refractive index (USG)
|
|
What does the refractive index depend on?
|
-the # of particles/volume
-types of particles (larger particles contribute more) |
|
In health, what is the refractive index primarily due to?
|
-electrolytes
-urea -creatinine |
|
How is osmolality determined?
|
-freezing point osmometer
-the lower the freezing point of the urine, the high [solids] present in the urine |
|
Osmolality
-definition |
-# of particles/volume
|
|
Why is urine osmolality important?
|
-the resorption of water is dependent on osmolality not Specific Gravity
|
|
When is there not good correlation between USG and Osmolality?
|
-USG will overestimate solute concentration with a greatly increased [protein] or [glucose]
|
|
What does the USGref tell us?
|
-most of the water concentrating that affects specific gravity occurs in the distal nephron
|
|
Hyposthenuria
-USGref -what does this tell us |
- < 1.007
-the urine osmolality is less than the plasma osmolality |
|
Isosthenuria
-USGref -what does this tell us |
- 1.007 - 1.013
-the urine osmolality is about the same as the plasma osmolality |
|
What 3 components must be present in order to produce concentrated urine?
|
-ADH must be present
-tubules must respond to ADH -a concentration gradient must be present |
|
What components must be present in order to produce hyposthenuric urine?
|
-functional loop of henle (remove solute but not water
-NO ADH activity |
|
Concentration of solute in urine depends on:
|
-amount of solute excreted in the urine over time
-the amount of H2O excreted by the urinary system over the same time interval |
|
When performing a urine chemical analysis by dipstick method, what is important to consider?
|
Either:
-volume of urine produced per day or -USGref |
|
Typical Urine pH
-carnivores -herbivores |
-carnivores: acidic
-herbivores: alkaline |
|
Aciduria
-definition |
-pH < 7.0
-kidneys are excreting H+ from the blood |
|
Alkalinuria
-definition |
-pH > 7.5
-kidneys are returning H+ to the blood |
|
Protein in urine
-normal findings |
-none except for some in dogs (albumin typically)
|
|
Methods of measuring protein in urine
|
-reagent strip method
-SSA turbidity |
|
Proteinuria
-types |
-Prerenal
-Glomerular -Tubular -Hemorrhagic/Inflammatory |
|
Prerenal Proteinurias
-common conditions |
-hemoglobinuria (intravascular hemolysis)
-myoglobinuria (acute muscle necrosis) -Bence Jones proteinuria (lymphoid neoplasm) |
|
Glomerular Proteinuria
-common conditions |
-glomerulonephritis
-glomerular amyloidosis -Protein losing nephropathy and renal failure |
|
Tubular Proteinuria
-common conditions |
-acute tubular toxicity
-congenital disorder |
|
Hemorrhagic or Inflammatory Proteinuria
-common conditions |
-hematuria: urinary tract hemorrhage
-pyuria: urinary tract inflammation |
|
Glucose
-expected test reaction -why? |
-negative
-all glucose should be getting reabsorbed in the proximal tubule |
|
Glucose
-testing method |
-reagent strip method that uses glucose oxidase to convert glucose to gluconic acid
|
|
Glucosuria
-types |
-hyperglycemic glucosuria
-renal glucosuria |
|
Hyperglycemic glucosuria
-pathogenesis |
-a greatly increased plasma [glucose] causes glucose to filter into the ultrafiltrate. The amount of glucose in the ultrafiltrate exceeds the renal threshold for reabsorption
|
|
Animal with the highest renal threshold for glucose reabsorption
|
-cat
|
|
Renal glucosuria
-pathogenesis |
-plasma [glucose] is WRI but tubular disease causes defective renal resorption of glucose
|
|
Osmotic diuresis due to glucosuria
-pathogenesis |
-Inc. [glucose] in tubular fluid
-decreased osmotic gradient -decreased water reabsorption in tubule -constant urine volume --> Polyuria |
|
Are proteins osmotic agents?
|
-No
|
|
Ketones
-produced by |
-hepatocytes
|
|
Ketone bodies
|
-acetoacetate
-beta-hydroxybutyrate -acetone |
|
Primary ketone body detected by the reagent strip test
-why |
Acetoacetate
-acetone is volatile and is lost very quickly -beta-hydroxybutyrate is not a ketone |
|
Reasons for increased Ketogenesis
|
-excess catabolism of fatty acids by hepatocytes
-decreased insulin acitivity or increased glucagon activity |
|
Excess ketogenesis is common in:
|
-diabetes mellitus
-bovine ketosis |
|
What does ketonuria represent?
|
-there is excretion of acetoacetate and beta-hydroxybutyrate
-causes a resultant hyponatremia and hypokalemia because the ketones are anions |
|
Heme in urine
-tests |
-reagent strip
-hematase tablet |
|
Heme in urine
-tests method of detection |
-detect peroxidase activity of heme
|
|
Types of heme-uria:
|
-hematuria
-hemoglobinuria -myoglobinuria |
|
Hematuria
-causes |
-erythrocytes entering urine via hemorrhage into the urinary tract
-renal -bladder -urethra |
|
Hemoglobinuria
-causes |
-intravascular hemolysis
-hemolysis after erythrocytes enter urine (will not have a concurrent hemoglobinemia) |
|
Myoglobinuria
-causes |
-myocyte necrosis or damage
-excessive exertion -rhabdomyosis in horses |
|
Which type of heme-uria will the patient have concurrent pink plasma?
|
-hemoglobinuria
|
|
What condition needs to be present for hemoglobinuria to occur due to cells bursting in the urine?
|
-a low specific gravity (<1.015) causing the blood cells to swell and burst in the urine
|
|
What animal is expected to have trace levels of bilirubin present in the urine?
|
-dog
|
|
Forms of Bilirubin detected by the reagent strip test
|
-conjugated bilirubin
-occasional unconjugated bilirubin bound to albumin |
|
Bilirubinuria
-causes |
-hemolytic icterus (formation > excretion in bile)
-hepatobiliary disease (cholestasis) |
|
Leukocytes in urine
-vocab |
-pyuria
|
|
Erythrocytes in urine
-vocab |
-hematuria
|
|
Bacteria in urine
-vocab |
-bacteriuria
|
|
Casts in urine
-vocab |
-cylinduria
|
|
Crystals in urine
-vocab |
-crystaluria
|
|
Locations for possible sites of pyuria determined by route of sample collection
-voided -catheter -cystocentesis |
-voided: any genito-urinary tissue
-catheter: urethra, bladder, kidneys, prostate -cystocentesis: bladder, kidneys, prostate |
|
Types of casts that can be formes
|
-hyaline
-fine granular -coarse granular -epithelial -leukocyte -erythrocyte -waxy |
|
Types of casts indicative of active tubular degeneration
|
-fine granular
-coarse granular -epithelial |
|
Epithelial cells in urine
-causes |
-few = normal
-iatrogenic -hyperplastic mucosa from inflammation -neoplastic mucosal cells |
|
Ions in urine that can combine to form crystals
|
Cations:
-Ca2+ -Mg2+ -NH4+ -Na+ Anions: -Phosphates -Carbohydrates -Oxalate -Urate -Bilirubin |
|
Factors promoting crystal formation in urine:
|
-concentrations of ions in urine
-pH -temperature -inhibitors to crystal formation |
|
Crystals more common in acidic urine
|
-ammonium biurate
-bilirubin -calcium oxalate -cystine -urate and uric acid |
|
Crystals more common in alkaline urine
|
-calcium carbonate
-calcium phosphate -magnesium ammonium phosphate |
|
Ammonium biurate crystalluria
-due to |
-urate receptor defect (breed variation: dalmation, bulldogs, russian terrier)
-decreased urate resorption by renal tubules or -hepatic dysfunction -increased renal excretion of NH4 and urate -decreased urate conversion to allantoin |
|
Urate
-derived from |
-breakdown of purines (A, G)
|
|
Bilirubin crystalluria
-due to |
-healthy dog with concentrated urine
-increased renal excretion of bilirubin from an icteric disorder |
|
Calcium oxalate crystalluria
-due to |
-inc. excretion of calcium
-increased excretion of oxalates |
|
Calcium oxalate sources
|
Calcium oxalate monohydrate:
-ethylene glycol -ruminant diet Calcium oxalate dihydrate: -healthy dog with concentrated urine -ethylene glycol -ruminant diet -horse diet |
|
Urate Crystalluria
-causes |
-Breed variation (dalmation, bulldog)
-hepatic dysfunction (decreased conversion to allantoin) |
|
Calcium carbonate crystalluria
-common in |
-herbivores
-no pathological significance |
|
Calcium phosphate crystalluria
-due to |
-healthy dog with alkaline urine
-UTI -hypercalcuria |
|
Magnesium ammonium phosphate crystalluria
-aka |
-Struvite
|
|
Struvite crystalluria
-due to |
-degredation of urea from bacteria or delayed urinalysis
|
|
Pathogenic Mechanisms of Polyuria
|
-chronic renal failure
-acute renal failure -post-obstructive diuresis -diabetes mellitus -hypercalcemia -canine pyometra -hypokalemia -hypoadrenocorticism -liver failure -central diabetes insipidus -hyperadrenocorticism -psychogenic polydipsia |
|
Chronic renal failure
-major mechanisms contributing to polyuria |
Too few functional nephrons
-solute diuresis -no tubular response to ADH |
|
Acute renal failure
-major mechanisms contributing to polyuria |
-no tubular response to ADH
|
|
Post Obstructive Diuresis
-major mechanisms contributing to polyuria |
-solute diuresis
-no tubular response to ADH |
|
Diabetes mellitus
-major mechanisms contributing to polyuria |
-solute diuresis
-possible decreased medullary tonicity |
|
Hypercalcemia
-major mechanisms contributing to polyuria |
-Calcium interferes with tubular response to ADH
|
|
Canine Pyometra
-major mechanisms contributing to polyuria |
-no tubular response to ADH
|
|
Hypokalemia
-major mechanisms contributing to polyuria |
-no tubular response to ADH
|
|
Hypoadrenocorticism
-major mechanisms contributing to polyuria |
-dec. medullary tonicity
-dec. release of ADH |
|
Liver failure
-major mechanisms contributing to polyuria |
-dec. medullary tonicity
-NH4 interference with ADH |
|
Central Diabetes Insipidus
-major mechanisms contributing to polyuria |
-dec. release of ADH
|
|
Hyperadrenocorticism
-major mechanisms contributing to polyuria |
-cortisol causes a dec. in ADH release
|
|
Psychogenic polydipsia
-major mechanisms contributing to polyuria |
-dec. plasma osmolality causes a dec. in ADH release
|
|
Isosthenuria
-definition |
-urine osmolality = plasma osmolality
|
|
Isosthenuria
-USGref range |
-1.007 - 1.013
|
|
Normal plasma concentration
|
-300 mmol/kg
|
|
Hyposthenuria
-USGref value |
- <1.007
|
|
Mechanisms of polyuria where solute diuresis contributes to the problem
-why |
-chronic renal failure (too much solute for the remaining functional nephrons)
-post-obstructive diuresis (solute accumulates during obstruction and then overwhelms the nephrons after) -diabetes mellitus (glucose in the tubular fluid reduces the osmotic gradient) |
|
Mechanism of polyuria where dec. medullary tonicity contributes to the problem
-why |
-chronic renal failure (damaged medullary tissue; poor blood flow; dec. sodium and Chloride transport in the ascending limb
-Diabetes mellitus (medullary washout) -hyperadrenocorticism (persistent hyponatremia and hypochloremia leading to dec. Na and Cl transport) -liver failure (dec. urea synthesis) |
|
Mechanisms of polyuria where dec. tubular response to ADH contributes to the problem
-why |
-chronic renal failure; acute renal failure; post obstructive diuresis (damage to renal tubular cells)
-hypercalcemia ( free Calcium interferes with ADH activity) -pyometra (endotoxins interfering with ADH activity) -hypokalemia (tubules less responsive to ADH) -liver failure (increase in NH4 that enters tubules causes less response to ADH) |
|
Mechanisms of polyuria where dec. ADH contributes to the problem
-why |
-hypoadrenocorticism (less Na and Cl leads to hypoosmolar plasma, causing less of an ADH stimulus)
-Central Diabetes Insipidus (dec. ADH secretion from pituitary problem) -Hyperadrenocorticism (increased cortisol inhibits ADH) -Psychogenic polydipsia (increased water consumption causes hperosmolar plasma and less of an ADH stimulus) |
|
Normal concentrated USG
-cat -dog -horse and cattle |
-cat: > 1.080
-dog: 1.060 -horse and cattle: 1.045 |
|
USG 1.014 - 1.030
-definition |
-impaired ability to concentrate
|
|
Dehydrated animal with a USG 1.014 - 1.030 could have?
|
-developing renal failure
-diabetes mellitus --> glucosuria -hypoadrenocorticism -partial diabetes insipidus |
|
Dehydrated animal with isosthenuric urine if azotemic, could have?
|
-renal insufficiency/failure
-hypoadrenocorticism |
|
Dehydrated animal with hyposthenuric urine could have?
|
-diabetes insipidus
-hypoadrenocorticism |
|
Oliguric animal with USG > 1.030 could be?
|
-trying to concentrate
|
|
Oliguric animal with USG 1.014 - 1.030 could be?
|
-acute renal failure (if azotemic)
|
|
Oliguric animal with USG 1.007 - 1.013 could be?
|
-oliguric renal failure
-oliguric acute renal failure |
|
Glucosuric animal with USG > 1.020 could be?
|
-diabetes mellitus
|
|
Glucosuric animal with USG 1.007 - 1.020 could be?
|
-diabetes mellitus and medullary washout
|
|
Hyponatremia and Hypochloremia with USG > 1.020 could be?
|
-hypoadrenocorticism & trying to concentrate
|
|
Hyponatremia and Hypochloremia with USG 1.007 - 1.013 could be?
|
-hypoadrenocorticism
-possible chronic renal failure |
|
Hyponatremia and Hypochloremia with USG < 1.007 could be?
|
-hypoadrenocorticism
-decreased medullary tonicity -decreased plasma osmolality |
|
Explain variation in amount of Creatinine in urine
|
-amount of creatinine released each day should be constant, so variation is due to amount of H2O secreted
|
|
Gold standard for measuring protein loss per day via kidneys
|
-collect all urine produced during 24 hrs
-measure volume and protein concentration |
|
How can urinary excretion of protein be assessed?
|
-compare urine excretion of and creatinine on a random sample
|
|
What can an increased protein/creatinine ration be due to
|
-inc. filtered load
-inc. tubular absorption -dec. tubular resorption |