Nephrology, Urology Flashcards
Predisposing factors for proteinuria in dogs?
HAC, hyperlipidemia, pancreatitis, GB mucocele
What are the roles and effects of fibroblast growth factor (FGF)-23?
Phosphaturic hormone associated with CKD-mineral bone disorder (MBD).
Released from osteocytes in response to increased serum phosphorus & calcitriol concentrations promotes PO4 urinary excretion by downregulation of Na-PO4 co-transporter in renal PT cells & inhibition of calcitriol synthesis.
Binds to FGF receptor-α-klotho complex (klotho = co-factor).
Circulating FGF-23 concentrations increase with advanced CKD stages in cats & dogs. Mechanisms: decreased FGF-23 clearance due to decreased GFR, compensation for phos accumulation in the body and for decreased klotho protein concentrations.
Creatinine - filtered or secreted?
Creatinine is freely filtered by the glomeruli. 10%–30% is secreted by the PCT in the basal state. Under normal circumstances, the rates of creatinine production and excretion are fairly constant.
Describe what disturbances of calcium homeostasis occurs after initiating a phosphate-restricted diet in cats with CKD, and its adverse effects?
xxx
After initiating a phosphate-restricted diet, hyperCa-enhanced renal Ca excretion acts as a compensatory mechanism - but extent of compensation is inadequate to prevent increments in plasma [Ca].
HyperCa –> reduction in GFR
Mechanisms of hyperCa, and which is applicable to CKD?
- Decreased urinary excretion
- Increased intestinal absorption
- Increased bone resorption
(can be a combo)
CKD: impaired calcium
excretory function.
Familial proteinuric kidney disease - which breeds & pathomechanism?
Underlying gene mutations often unknown.
Defects in the production or assembly of collagen IV (Alport syndrome).
Bull Terrier, Dalmatian, English Cocker Spaniel, Samoyed.
Hereditary focal segmental
glomerulosclerosis is overrepresented in which breed? Concurrent with what other condition?
Soft Coated Wheaten Terriers
PLE
Juvenile nephropathy (<3yo) - which breeds?
Dogue de Bordeaux, Rottweiler, Gordon Setter
Familial renal amyloidosis - which breeds (D/C)?
Shar-Pei, Beagles, English Foxhounds, Bracchi Italiani
Abyssinians
Why is serum P concentration unreliable when clinically assessing cats with CKD?
Many regulatory mechanisms occur with progressive CKD. So many measures of renal function (GFR, US, sCr, FGF-23, PTH) may be altered prior to increase in serum P in CKD.
What association has been observed between FGF-23 & SDMA in cats with CKD?
In geriatric cats with early CKD but not azotemia, FGF-23 concentration is associated with SDMA (indicative of decreased GFR).
What association has been observed between FGF-23 & SDMA in cats with CKD?
In geriatric cats with early CKD but not azotemia, FGF-23 concentration is associated with SDMA (indicative of decreased GFR).
SDMA
- What does it stand for?
- Origin?
- Diagnostic utility?
- What extra-renal factors cause an increase in SDMA?
- Symmetric dimethylarginine.
- Methylated arginine. Derived from intranuclear methylation of L-arginine by protein-arginine methyltransferase –> released into circulation after proteolysis.
- Primarily eliminated by renal excretion, so highly correlated with GFR - useful as early indicator of renal dysfunction than sCr.
- Factors: thyroid dysfunction (e.g. hypoT post I131), psychogenic polydipsia (dogs), skin disease (dogs) - unknown mechanism, breed (Greyhounds have higher SDMA)
When performing US-guided renal biopsies:
- What biopsy evaluation techniques are used?
- What is the recommended no. of glomeruli for diagnostic quality samples?
- Min 10 glomeruli per sample, prefer 15-20 for LM
- Light microscopy, immunofluorescence, TEM
Ammonium urate urolithiasis - what 2 disease entities?
Predisposed dog & cat breeds?
1) Hepatic portovascular anomalies
- Yorkies, cats with PSS
2) Inherited defect of hepatic uric acid transporter (SLC2A9 gene mutation). Lack of uric acid degradation to its more soluble metabolite (allantoin) > increased urinary excretion of uric acid > hyperuricosuria. NOT X-linked, homozygous recessive.
- Dalmatians (all secrete lots of uric acid but only 5% stone formers), almost all male (9:1), Eng Bulldogs, Black Russian Terrier
3) Unknown (cats) - Egyptian Mau, Siamese, Birman
Cystine uroliths - types, gene mutation, breeds?
Gene mutations associated with cystine tubular malabsorption.
Type Ia: SLC3A1 gene, autosomal recessive. Big dogs - Newfoundlands, Labs, Landseers
Type IIa: SLC3A1 gene, autosomal DOMINANT with incomplete penetrance. Active dogs - ACD, Border Collies
Type III: sex linked, androgen dependent. Intact males (esp Mastiffs, Eng & French Bulldogs)
Radiolucent uroliths?
Xanthine
Cystine (can be radioopaque)
Urate
(can’t see you)
Extra-renal factors that can affect SDMA?
DM (cats) - reduce SDMA
What no. of colony forming units is associated with a significant UTI?
> 10^5 CFU/ml
What are the challenges in diagnosing Corynebacterium urealyticum UTI?
Aerobic, non-spore forming, lipophilic G+ bacillus. Very slow growing and does not grow well after overnight incubation.
Enriched culture (e.g. with blood agar) for 72hrs+ is recommended, or risk false negative.
What is the microbiome composition of urine in healthy dogs? What findin was associated with bacterial communities in urine?
Low presence of bacteria and/or fungi, identified on next-generation sequencing molecular diagnostics but not routine culture.
Struvite crystals.
JVIM consensus: Describe the tiers for dogs diagnosed with glomerular disease?
Tier I persistent renal proteinuria.
- I-A: subclinical
- I-B: proteinuria + hypertension (+/- TOD)
Tier II renal proteinuria + hypoalb.
- II-A: proteinuria + hypoalb (+/- complications - oedema, TE)
- II-B: proteinuria + hypoalb (+/- complications) + hypertension
Tier III renal proteinuria + azotemia
- III-A: proteinuria + azotemia
- III-B: proteinuria + azotemia + hypertension
- III-C: roteinuria + azotemia + hypoalb +/- hypertension
ACVIM consensus:
Drugs associated with glomerulonephropathy & brief MOA?
PPA (hypertension), steroid (incr glomerular permeability), sulfonamides (crystalluria, tubular necrosis, interstitial nephritis, glomerular lesions as part of a vasculitis syndrome), TKI (VEGF over/underexpression + incr intraglomerular P > hypertension)
Infectious causes of renal proteinuria?
Parasitic - HWD
Bacterial - Ehrlichia (canis, chaffeensis, ewingii), lepto (usually tubular), Bb, Rickettsial/RMSF (acute), Bartonella, Anaplasma (phago, platys), Brucellosis, Mycoplasma
Viral - CAV-1
Fungal - Blasto
Protozoa - Hepatozoon, Leishmaniasis, Trypanosomiasis
ACVIM consensus
What 3 microscopic methods & special stains are used for renal biopsy evaluation?
1) Transmission electron microscopy (TEM; ultrastructural) - glutaraldehyde
2) Immunofluorescence (IF) - Michel’s medium
- Ab against IgG/IgM/IgA, C1q, C3, lambda & kappa light chains»_space; detect immune-complex deposits.
3) Light microscopy (LM) - formalin fixed
Special stains:
- H&E
- Masson’s trichome (MT) for collagen & CT (amyloid looks mottled blue)
- PAS-hematoxylin for junction between tissue compartments
- Jones methenamine silver (JMS) for fine structures of glomerular BM (useful for immune complex deposits)
- Congo red for amyloid.
Requirements for diagnostic renal bx sample?
Ciancolo paper
3um sections, minimum 10 glomeruli.
16ga needle usually ok.
What immunopathological feature is useful to differentiate between reactive vs primary amyloidosis?
Limitation of trucut method of renal biopsies?
Comparisons in distribution of renal amyloidosis in dogs vs cats?
Congo red–stained amyloid deposits with reactive amyloidosis (amyloid A) lose their affinity for Congo red after K permanganate oxidation (decolourise). Whereas primary amyloidosis (amyloid L) is resistant to KP.
Trucut method obtains renal cortical biopsies, will miss medullary lesions.
Dogs - usually just glomerular involvement, cortical & medullary interstitium less involved. EXCEPT Chinese Shar Peis. Cats - renal amyloidosis usually medullary +/- glomerular.
ACVIM consensus statement
What is the 1st vs 2nd-line anti-proteinuric tx recommended in dogs?
When monitoring a patient receiving anti-proteinuric tx, what are the tolerable limits for parameters monitored?
1st line: ACE-I
2nd line: ARB
SCr: increase <30% (stage 1-2 CKD), <10% (stage 3), 0% (stage 4)
K+ <6.0mmol/L
SBP 120 to <180mmHg
ACVIM consensus statement
What is the benefit of O3FA supplementation in glomerular disease? What is the recommended ratio of O3 vs O6 FA dietary supplementation?
Renoprotective; suppresses glomerular inflammation and coagulation by interfering with production of proinflammatory prostanoids (derived from arachidonic acid via COX pathway), lowers intraglomerular pressure.
Recc ratio O6:O3 = 5:1