114. Kidney Flashcards
blood supply to kidney
renal arteries (dorsal) from Aomultiple arteries reported (more often in left kidney)interlobar–>arcuate (at corticomedullary jxn)–>interlobular–>afferent glomerularsmall capillaries seen in the capsule arising from phrenicoabdominal and adrenal arteries; anastomose with primary renal arteries “arterial circle”vasa recti from cortex and into medulla for resorption VEINS: left renal receives blood with left ovarian and testicularmutliple veins 13% dog 10% cats
what is the functional unit of a kidney
nephron–>renal corpuscle (glomerulus and Bowman’s capsule) and renal tubules (ending at the collecting duct)glomerulus contains podocytes which sit on basement membrane and interdigitate to create pores btwn cells for filtration
where is the macula densa located
btwn glomerulus capillary network and afferent arterymaintain auto regulation of renal blood flow
filtration at the level of the glomerulus
< 60 kDa freely pass (water and small particles)>60kDa (albumin 69 kDa) have limited ability to passinherent negative charge of basement membrane also repels other negatively charged molecules (like albumin)glomerular filtrate is equivalent to plasma—300 mOs/L
normal anticipated urine production
1-2 ml/kg/hr
estimated renal blood flow
kidneys receive ~25% of animal’s cardiac output (HIGH BLOOD FLOW–greater than any capillary bed in the body)cortical flow is highestrenal blood flow = renal perfusion pressure/renal vascular resistancetone of afferent and efferent arterioles affect GFRincr tone of afferent, decr GFRdecr tone of efferent, incr GFR
what is the concentrating ability based on
based on renal medullary hyperosmolarity (which is maintained by vasa recti counter current mechanism)hi medullary interstitium 1200-1400 mOs/L (50% made up from urea)if blood flow thru vasa recti is high (vasodilation, increased arterial P, increase fluid volume), concentrating ability is decreased or “medullary wash out”
3 mechanisms to maintain medullary hypertonicity
- urea diffusion into interstitium2. limited ability for water diffusion3. active transport of electrolytes to interstitium in thick proximal loop of Henle **
diagnostic tests for the renal dz patient
- PE 2. MDB3. BP4. BMBT (impaired with uremia)5. crossmatch/coagulation panel6. Ab rads (also T rads if neoplasia, trauma suspected)7. ab US +/- aspirate or biopsy8. IV excretory urogram/pyelogram9. CT with contrast angiography10. MR angiography11. scintigraphy to determine GFR (total or individual)
risk of hemorrhage during or after surgery is increase in what patients?
azotemichypertensivethrombocytopenic
normal kidney size on radiographs
N canine kidney 2-2.5 times length of adjacent vertebraN feline kidney 2-3 times length of adjacent vertebra
type of intravascular contrast studies
—excretory urogram or IV pyelogram (can also inject into renal pelvis)does NOT provide quantitative informationposible that a kidney with very little function will opacify therefor do NOT confuse opacification with renal functionrads taken immediately, 5, 20, 40 minutes after injection contrast dose 400 mg I/kg
toxicity of renal IV contrast studies
ARF—hypotension, anaphylaxis, allergic reactionsiodinated nonionic preferrediohexol (omnipaque)–240 mg/ml I
phases of an excretory urogram
- renal angiographic: immediate, arterial supply2. renal phase or blush: parenchymal3. excretory: collecting ducts to bladder
true renal a genesis vs dysgenesis
a genesis lack kidney and ureterdygenesis lack kidney but ureter may be present RIGHT kidney is more frequently reported check for other urogenital abN
renal calculi
mostly calcium salts (siamese and bichon frises calcium oxalate)do NOT dissolve with medical protocolstx options for stone removal:– lithotripsy– nephrotomy– pyelolithotomy– nephrectomy is end stage infected or nonfunctional
T/F In cats with mild to moderate renal disease, the presence of renal calculi was NOT associated with progression of renal disease or in a difference in mortality rates from renal dz
TRUEpresence of stone did not put them at a higher risk of dz progression and/or mortalityresection of perirenal pseudocysts also did not prevent progression of any underlying renal disease
types of renal neoplasia
majority of primary renal tumors MALIGNANTcats–LSAdogs–renal cell carcinomaother tumors: TCC, nephroblastoma, renal cystadenocarcinoma (nodular dermatofibrosis and uterine leiomyomas—-GSD), HSAab mets 50% (liver and LN) in dogstx unilateral nephrectomy
contraindications to renal biopsy
–known end stage–owner unwilling to pursue further therapy–coagulopathy/severe hypertension–abscess–cysts–extensive polynephritis–ureteral obstruction–severe hydronephrosis
appropriate renal biopsy
need 5-6 glomeruli, spring loaded biopsy instrument–percutaneous blind biopsy–US guided biopsy**–keyhole biopsy (flank open)–open laparotomy wedge/incisional occlusion renal artery for 20 min–laparoscopic biopsymajor implications < 10% (severe hemorrhage)
two methods for nephrotomy
- bisectional nephrotomy: sharp dissection2. intersegmental nephrotomy: slower, technically demanding, allows individual ligation of encountered vessels but less hemorrhage**no difference in GFR with either technique
GFR after nephrotomy incision
closure of nephrotomy decr GFR 40-50% 21 days post opno clinical azotemia seensuture less closure minimally disturbed GFR
indications for partial nephrectomy
“nephron sparing”very small tumors or traumamay be more appropriate option for animals with decrease GFRuncommonly performed—most often nephrectomy/nephroureterectomy
if an owner refuses to spay their pet, what complication can occur after left nephrectomy
damage to left gonadal veinif remaining intact, need to ligate renal vein upstream (towards the kidney) to avoid damage to gonadal/ovarian vein
what is renal descensus
mobilization of the kidney caudal (as with renal transplant—into iliac fossa)
what is psoas hitch
cranial movement of bladder
how much of normal renal function can return after 4 weeks of total obstruction
25%
giant kidney worm
dioctophyma renale
