Introduction to Urology (Rolph) Flashcards
Name some (or all) the functions of the kidneys.
- Excretes waste
- Retrieves filtered particles
- Maintains acid/base balance
- Regulates BP
- Monitors/modifies oxygenation (erythropoietin production)
What 3 activities regulate fluid-electrolyte balance and where are they carried out?
Carried out by the nephron
- Glomerular filtration
- Tubular secretion
- Tubular reabsoprtion
What percent of cardiac output do the kidneys recieve?
25%
What does the high, constant renal blood flow allow for?
- High = metabolic requirements and to maintain GFR
- Constant = Excretion and homeostasis
What percentage of oxygen do the kidneys consume?
~8%
What are some conditions associated with decreased renal blood flow?
- Volume depletion
- Heart failure (abnormal circulation)
- Hypotension (long-term kidney effects)
What condition is associated with increased renal blood flow?
Hypertension
What is the kidney’s role in controlling blood pressure?
Insert image, page 8
Where is antidiuretic hormone released from and what does it cause?
Released from posterior pituitary
- Drop in blood pressure
- Decreased blood volume
- Beta-adrengergic stimulation
What are the ADH receptors and their effects?
- V1 receptors → promotes vasoconstriction
- V2 receptors → increased H2O reabsorption
Name the components of the nephron and label them.
Insert image, page 10
Where is angiotensin II (ang II) generated and what does it interact with?
- Produced in afferent arteriole
- Interacts w/ AT1 receptors on cellular components of nephron
Define renal disease.
Presence of morphological or functional lesions in one or both kidneys, regardless of extent
- Renal disease ≠ azotemia
- Renal disease ≠ renal failure
Define azotemia.
Abnormal increased in the blood concentration of non-protein nitrogenous wastes (NPN, i.e. urea and creatinine)
What are the types and causes of azotemia?
- Pre-renal (perfusion): volume depletion, hypotension
- Renal: Parenchymal disease, infection, cysts, infalmmation, neoplasia, toxin
- Post-renal: obstruction or rupture of lower urinary tract
What is renal failure?
Clinical syndrome that occurs when kidneys are no longer able to maintain:
- Regulatory function
- Excretory function
- Endocrine function
What biochemical changes can occur with renal failure?
- Retention of nitrogenous solutes
- Fluid, electrolyte, and acid-base derangements
When does renal failure occur relating to nephron population?
Renal failure occurs when > 75% of the nephron population is non-functional
The function of what is used to assess renal function?
Glomerular function
The glomerular filtration rate is (directly/indirectly) related to renal functional mass.
Directly
What are the accurate technqiues to assess renal function?
- Clearance of radioisotopes w/ renal scintigraphy (best, most accurate)
- Iohexal/inulin/creatinine clearance tests
What are the indirect methods for assessing renal function?
- Serum urea levels
- Sreum creatinine levels
- Cystatin C
- SDMA (Symmetrical dimethylarginine)
What are some characteristics of urea (synthesis, excretion, concentration)?
- Synthesized in the liver
- Excreted by the kidneys
- Urea concentration in renal medulla helps maintain solute gradient
What are urea serum levels affected by?
- Species/age
- Liver function
- Dietary protein content
- Endogenous protein catabolism
- Renal function
What are the limitations of urea?
Subject to passive reabsoprtion in tubules
- Exacerbated by slower tubular flow rates → volume depletion
- Urea clearance not relaible estimate of GFR
What can lead to false positives in urea?
- GIT bleeding
- Intravascular hemolysis
- High protein diets
What is creatinine and its characteristics?
Biproduct of conversion of creatine to creatine phosphate
- Producted at a constant rate
- Dependant on muscle mass (grayhounds vs. puppies)
- Influenced less by diet
How is creatinine excreted?
Unchanged by the kidneys
How are serum creatinine concentrations affected?
- Increased: reduced renal clearance
- Decreased: reduced muscle mass, significantly in elderly or pateitns w/ cachexia
What are the limitations of creatinine testing?
- Does not tell you why the GFR has decreased
- Doesn’t discriminate between:
- Causes of azotemia
- Acute vs. chronic renal failure
- Reversible or irreversible renal failure
Severity of clinical signs of azotemia are (directly/indirectly/not directly) proportional to magnitude of creatinine increase.
Not directly
What is cystatin-C and its characteristics?
Small polypeptide protease inhibitor produced by all cells with a nucleus
- Freely filtered by glomeruli
- Doesn’t undergo tubular secretion
- Produced at constant rate in all tissues
- Excretion not dependent on age, sex, diet, or muscle mass (debated)
What is the accuracy of cystatin-C versus creatinine and what may be detected early?
Possibly more accurate than creatinine
- May detect early changes in GFR
What is cystatin-C potentiall affected by?
- Neoplasia
- Levels of C-Reactive Protein
- Thyroid dysfunction
- Glucocorticoid administration
What is SDMA and its characteristics?
Methylated form of amino acid arginine (produced in every cell and released into body’s circulation during protein degradation)
- Excreted almost exclusively by kidneys
- Correlates highly w/ GFR by inulin (r = 0.85)
How accurate is SDMA testing compared to creatinine?
Increased
- 17 months earlier in cats
- 9 months earlier in dogs
when there’s 40% decline in GFR
- useful in cases w/ normal creatinine
What can alter SDMA levels?
Emergeing evidence suggests diseases like hyperthyroidism alter SDMA levels
When collecting urine for an urinalysis, what are the options?
- Free flow
- Catheterization
- Cystocentesis
What are the advantages and disadvantages of each urine collection method?
- Free flow
- Contamination potential
- Non-invasive (used to r/o infection/check for glycosuria)
- Catheterization
- Contamination potential
- Difficult in female dogs, all cats
- Cystocentsis
- Best method for culture
- Blind vs. ultrasound guided
- Can lead to slight increase in RBC urine content
How is a cystocentesis performed?
- Ultrasound-guided or blind
- Positioning: lateral, dorsal, standing (cats) or “turned sheep” (dogs)
- Locate and stabilize bladder (DON’T SQUEEZE)
- Wet the site w/ alcohol
- Stabilize bladder w/ 1 hand
- Hold syringe so you can aspirate w/o changing position
- Confidently insert needle into bladder at 45 degree angle
- Slowly aspirate until you have adequate volume of urine
- If you don’t get urine, completely remove needle from abdomen
- Once sample is obtained, release hand stabilizing bladder, THEN remove needle from abdomen
What are the main things to assess with a urinalysis and what’s used?
- Color/clarity
- Concentration
- Dipstick
- Sediment
- Culture and sensitivity
- Urine Protein to Creatinine Ratio
How is the concentration assessed in a urinalysis?
- Osmolality
- Estimated by USG
- Hand-held vs. digital
- Hyperosmolar substances alter USG
What is the “normal” range of urine concentration in dogs and cats?
- Dogs: 1.030-1.065
- Cats: 1.035-1.090
Why is the “normal” urine concentration range of cats problematic?
Upper limit is too high for most in-house refractometers to detect
What are the ranges for hyposthenuria and isosthenuria?
- Hyposthenuria: < 1.009
- Isosthenuria: 1.010-1.015
- Hypersthenuria doesn’t really exist b/c it’s basically normal
What’re normal and abnormal water intake levels?
40-60 mL/kg/day
- Depends on diet and species
- > 100 mL/kg/day = polydipsia
What’s the dipstick’s main purposes, when is it not useful, and what affects it?
- Designed for humans → problem w/ veterinary medicine
- Not useful parameters: SG, nitrite, urolbilinogen, WBC
- Affected by: icterus, drugs (e.g. vitamin C, oxyglobin), urine temperature
When is bilirubinuria normal?
NORMAL dogs have bilirubinuria, NOT cats
What is the urine pH, and what’s normal range for dogs and cats?
H+ ion concentration of urine
- Normal dog and cat range: 6-7 (6.5)
How is pH related to diet?
- High protein = acid pH
- High vegetable content = alkaline pH
- pH tends to ride after a meal (‘alkaline tide’)
What can pH be associated with?
- Crystals
- Calculi
What conditions are associated w/ alkaline urine?
- Respiratory alkalosis
- Urinary tract infection
- Urine retention
- Alkaline tide
- Tubular disorder
What conditions are associated w/ acidic urine?
- Respiratory acidosis
- Severe vomiting
- Ketoacidosis
- Ethylene glycol toxicity
- Azotemia
How common is proteinuria?
Normally, minimal protein found in urine
- Range from: 1+ to 4+
What are the different etiologies for proteinuria?
- Inflammation and infectious
- Gross hematuria
- Chronic renal failure
- Protein-losing nephropathies
- GN, nephrotic syndrome, amyloidosis
- [Multiple myeloma (Benz Jones proteins)]
How is urine protein:creatinine ratio used?
Quantify the amount of protein present
What is the reference range for urine protein:creatinine ratio in dogs and cats?
- Dogs: <0.5
- Cats: <0.4
What are some conditions that increase protein/cause proteinuria?
- Infections
- Inflammation
- HAC
Is glucosuria normal or abnormal?
Glucose should NOT be present in normal urine
How does glucosuria affect the USG?
Glucosuria elevates the USG
What’s the renal threshold of glucose in dogs and cats?
- Dogs: 10-12 mmol/L
- Cats: 10-16 mmol/L
When assessing glucosuria, what should you check for?
- Ketones (ketonuria)
- Blood glucose levels
What conditions can cause glucosuria?
- Diabetes mellitus
- Hyperglycemia (stress induced)
- Renal tubular diseases (i.e. Fanconi syndrome)
- Infections (pyelonephritis, leptospirosis)
- Drugs (alpha-2 adrenoceptor agonists, Gentamycin, Chlorambucil [cats], Tetracycline exposure)
- Toxicixities (copper storage hepratopathy, ethylene glycol, lead, grapes, raisins, lilies)
- False + on dipstick associated w/ amoxicillin, cephalexin, enrofloxacin exposure
Is ketonuria normal?
NO
- Ketones should not be present in normal urine
What ketone(s) does a dipstick measure and what are the sensitivities and specificities, if applicable?
Dipsticks measure
- Acetoacetate
- Plasma ketones (100% sensitivity, 88% specificity)
- Urine ketones (82% sensitivity, 95% specificity)
What ketone is mainly produced in dogs and cats, and how is that measured?
Beta-hydroxybutyrate
- Can convert ot acetoaxetate w/ H2O2 (measure w/ dipstick)
What are the differentials for ketonuria?
- Diabetes mellitus w/ DKA
- High fat diets?
- Starvation?
- Drugs (N-acetylcysteine, Captopril, Penicillamine)
Is bilirubinuria normal?
- Normal in dogs (conjugate bilirubin in kidneys)
- Abnormal in cats (renal threshold x9 of dogs)
What are the causes of bilirubinuria?
- Liver disease
- Cholestasis
- Bile duct obstruction
- Hemolytic diseases
- Infections (Leptospirosis, FIP)
What are the characteristics of urobilogen?
- May normally be present inurine
- Urine strip may be inaccurate
- Intermittent excretion
- Source: bilirubin conversion in gut
How is urobilogen as an indicator of bile duct obstruction?
Poor indicator
What are the different types of hematuria?
- Gross (macroscopic)
- Occult (microscopic)
- Pseudohematuria
What are the differences between the types of hematuria?
- Gross (macroscopic)
- Sufficient blood to be seen w/ naked eye
- Urine may appear brownish-red
- Will increase UPC
- Occult (microscopic)
- Hematuria present but NOT visible to naked eye
- Pseudohematuria
- Red-brownish urine W/O intact RBCs
What can cause pesudohematuria?
- Hemoglobinuria
- Myoglobinuria
- Chemicals
What are some causes of hematuria in general?
- Systemic disorders (homeostatic defects)
- Renal (neoplasia, calculi, truama, infarction, cysts, glomerulonephritis, infection)
- Bladder, ureter, urethra (bacterial infection, calculi, trauma, neoplasia, polyps, cyclophosphamide therapy, feline idiopathic cystitis)
- Genital tract (prostatic disease, estrus, infection, neoplasia, trauma)
What should be investigated when hematuria is involved?
- Determine site of hematuria
- History
- Clinical Examination
- Bloods
- Full urinanalysis including urine culture
- Imaging
- Cytoscopy
- Vaginoscopu
- Cytology (vaginal cytology, prostatic wash)
What’s important in the history regarding hematuria?
- Bleeding noted from other sites?
- Trauma?
- Exposure to anticoagulant rodenticides?
- Timing of occurrence of blood (throughout urination or only at end)?
- Color of mucous membranes, urine, etc.
What’s important to check in the clinical examination when hematuria is involved?
- Other hemorrhage sites?
- Examine feces?
- Palpate kidneys and bladder
- Digital rectal examination
- Check blood pressure
What blood testing should be performed with hematuria?
- Hematology, blood smear
- Biochemistry
- Clotting times
What imaging should be performed when investigating hematuria and what should be looked at?
- Ultrasound kidney, bladder, prostate
- Double contrast pneumocystogram w/ retrograde urethrogram (bladder, urethra)
What’s the process of examining urine sediment?
- If dilute, centrifuge urine at low speed (2-3000 rpm) before examination
- Discard supernatant, leaving 0.2-0.5 mL in tube
- Resuspend last few drops in supernatant (aspirate w/ pipette)
- Place drop onto slide (± add drop of sedi-stain)
- Add coverslip (optional)
- Use subdued microscope lighting (condenser must be lowered nad iris diaphragam partically closed for optimal viewing/conspicuous constituents)
Where do casts seen in sediment examinations form?
DCT and ducts
What are hyaline casts and when are they formed?
Composed of solidified Tamm-Horsfall mucoprotein
- Low urine flow states
- Concentrated urine
- Acidic environments
How are granular casts developed?
Can develop either from
- Breakdown of cellular casts OR
- Inclusion of aggregates of plasma proteins (e.g. albumin or immunoglobulin light chains)
What are waxy casts and when are they seen?
- Considered final stage of cellular cast degeneration
- Usually seen in tubular injury (common w/ chronic renal disease, renal amyloidosis)
What are fatty casts and when are they seen?
Hyaline casts w/ fat globule inclusions formed by the breakdown of lipid-rich epithelial cells
- Tubular degeneration
- Nephrotic syndrome
- Hypothyroidism
What’s important about crystalluria and its presence?
- Some crystals (struvite, calcium oxalate) can occur in normal urine and can precipiate rapidly as it cools or evaporates on a slide
- Important not to overinterpret significance when seen in low numbers or when there’s no evidence of stone formation or secondary infection
Name the different types of crystals and if they’re concerning or not.
Insert images
What imaging techniques can be used to image the urinary tract?
- Ultrasonography
- Radiography/CT
When should ultrasonography be used to image the urinary tract?
- Observing renal size and general morphology including mineralization
- Assess bladder wall (possibly ureters)
- 70% sensitive for cystolith identification
- Assess prostate
When should radiography/CT be used to image the urinary tract?
- Assess renal size and location
- Assess bladder and urethrea (double contrast pneumocystogram and retrograde urethrogram)
- IVU can be performed (better on CT) to assess urine flow (care re nephrotoxicity)
What’s important regarding renal biopsies?
- Rarely indicated (won’t change tx or prognosis)
- FNA inaccurate, but may be useful in suspected lymphoma
- Try-cut or Surgical Biopsy preferred (may require EM if wanting to investigate closely)
What are some etiologies of renomegaly?
- Hydronephrosis (ureteral obstruction)
- Neoplasia
- Renal inflammation (acute nephropathy, acute phyelonephritis, FIP granulomas, leptospirosis)
- Amyloidosis
- Polycystic kidney disease
- Portosystemic shunts
- Acromegaly
What’s the occurrence of renal neoplasia and the different types with associated conditions?
- Relatively uncommon in dogs (less so in cats)
- Primary
- Renal adenocarcinoma
- Renal lymphoma
- Renal sarcoma
- Nephroblastoma (very rare)
- Metastatic renal neoplasia (rare; e.g. hemangiosarcoma)
- Occasiona benign renal tumors (rare)
What’s the occurence of renal carcinoma?
More common in dogs than cats
What are some signs of renal carcinoma?
- Few clinical signs in early stages
- Hematuria and weight loss
- Unilateral (usually) renomegaly
- Rarely causes renal azotemia
- Can cause polycythemia as paraneoplastic syndrome
- Can cause hypertrophic osteopathy as paraneoplastic syndrome
What is the polycythemia as a paraneoplastic syndrome in renal carcinoma due to and what can it cause?
- Due to erythropoietin production by tumor or due to renal hypoxia
- Can cause neurological signs
How do you diagnose renal carcinoma?
Ultrasound-guided biopsy
What percentage of renal carcinoma patients have metastases at diagnosis?
50%
How do you treat renal carcinoma?
- Ensure sufficient function in contralateral kidney (IVU)
- Nephrectomy (remove all of part of kidney)
What’s the prognosis of renal carcinoma?
MST (dogs): 16 months w/ tx
Renal lymphoma is (more/less) common in cats then dogs and (may/may not) affect both kidneys.
- More common in cats than dogs
- May affect both kidneys
How does renal lymphoma present?
- Renomegaly
- Weight loss
- Inappetence
- PU/PD
- Commonly causes renal azotemia
Where does renal lymphoma usually spread?
Tendency to spread to CNS OR nose
How do you diagnose renal lymphoma?
- Renal ultrasound
- FNAs of kidneys
What’s the treatment for renal lymphoma?
- Multi-agent chemotherapy (COP or CHOP)
- Azotemia may resolve w/ tx
What’s the prognosis of renal lymphoma?
- ~60% go into complete remission (cats)
- MST (cats): 91 days w/ tx
How is polycystic kidney disease shared and who’s affected?
Affects Persian and Persian cross cats
- Autosomal dominant gene
- Mutation in PKD-1 gene
- Occasional cases of PKD in cats/dogs W/O PKD-1 gene mutation
How can the spread of polycystic kidney disease be slowed?
- Genetic testing available
- Breeding program (lead to marked reduction in prevalence)
What’s the diagnostic sign of polycystic kidney disease and how is it seen?
- Multiple cysts form in both kidneys
- Increase in size and # over time
- Seen on ultrasound
What’s a negative implication of polycystic kidney disease?
Can cause renal failure in adulthood
What other breeds are affected by inherited polycystic kidney disease?
- Bull terriers
- Cairn terriers
- WHWT
