Azotemia & Acute Kidney Injury Flashcards
What are the major components of the upper and lower urinary tracts?
UPPER = kidneys, proximal ureters
LOWER = caudal ureters, bladder (+ detrusor), urethra (+ internal sphincter), external sphincter of distal urethra
What is the functional unit of the kidney?
nephron —> glomerulus, arterioles, JG apparatus, tubules, and collecting ducts responsible for balancing fluids, blood pressure, and filtration
What are 4 functions of the kidneys?
- regulation of blood volume and HCT
- regulation of extracellular fluid volume and composition
- regulation of systemic arterial blood pressure
- regulation of acid-base plasma concentration of electrolytes, minerals, and metabolic waste products
What 4 values are used to assess renal function?
- BUN
- creatinine
- urinalysis
- SDMA
What values are given to USG? How must they be evaluated?
- HYPOSTHENURIA = < 1.008
- ISOSTHENURIA = 1.008-1.012
- HYPERTHENURIA = > 1.012
one isn’t better than the other - must be related to hydration status and signs in the patient
What is the most common value of properly concentrated urine in dogs and cats?
> 1.030
> 1.035
What are 4 common signs of abnormal kidney function?
- azotemia - increased BUN and creatinine
- increased SDMA
- inappropriate urine concentration
- proteinuria
What are the 3 classes of azotemia? What causes each?
- PRERENAL - dehydration and low volume status; concentrated urine (kidneys are still functioning!)
- RENAL - direct kidney disease; USG < 1.030-1.035, usually isosthenuric
- POSTRENAL - no outflow causes a buildup of toxins, usually caused by obstructions or ruptures (PE signs and imaging); USG varies
What is the difference between acute kidney injury and failure?
AKI - sudden onset of renal parenchymal injury due to a variety of acute diseases and is a continuum of functional and renal parenchymal damage (weeks to months to recover)
ARF - rapid injury to the kidneys and subsequent accumulation of metabolic toxins and fluid, electrolyte, and acid-base balance alterations
What is chronic kidney disease?
any structural, functional abnormality, or both or one or more kidneys three months or longer
- irreversible and progressive
What is the general approach to acute azotemia?
- assess USG to determine origin
- determine if acute or chronic if renal
- palpate bladder and make sure patient can or has been urinating
- determine if there are any risk factors to kidney injury are present
- discontinue any nephrotoxic drugs
- assess hydration and provide fluid therapy
- symptomatic therapy: GI signs, hypertensive, proteinuria
What history, hemogram findings, and renal structure is associated with AKI?
ischemia or toxicant (ethylene glycol, raisins, lilies)
normal or increased HCT
swollen kidneys
What history, hemogram findings, and renal structure is associated with CKD?
renal disease or PU/PD
nonregenerative anemia (decreased EPO)
small, irregular kidneys
What biochemical changes are associated with AKI?
- hyperkalemia (oliguria)
- severe metabolic acidosis
What biochemical changes are associated with CKD?
- normal or hypokalemia
- normal or mild metabolic acidosis
What urine sediment, BCS, clinical signs, and renal echogenicity is associated with AKI?
active sediment with normoglycemic glucosuria
good BCS
relatively severe clinical signs
usually normal
What urine sediment, BCS, clinical signs, and renal echogenicity is associated with CKD?
inactive sediment
weight loss
relatively mild clinical signs
dense renal cortices with loss of cortex-medulla junction
Causes of AKI:
What are the 4 minimum tests used for working up azotemia and AKI? What additional testing is helpful?
- CBC/chem
- UA
- BP —> hypertensive
- fundic exam —> retinal detachment, hyphema
- urine culture: pyelonephritis
- 4Dx: Lyme nephritis
- witness, PCR, MAT: Leptospirosis
- toxic metabolites
How are abdominal radiographs and ultrasounds used for diagnosing AKI?
RADIOGRAPHS - size of kidneys, stones in ureters
US - architecture of kidneys, perirenal fluid (hemorrhage), obstructions indicative of hydronephrosis, dilated pelvis indicative of pyelonephritis
What therapies are recommended for AKI?
- fluid therapy
- supportive care
- antiproteinurics (over-filtering can damage kidneys)
- antihypertensives
What should be monitored in patients with AKI?
- blood pressure
- body weight (should increase with hydration)
- urine output (catheters, bladder palpation)
What is the normal urine output? What are 3 changes?
1-2 mL/kg/day
- polyuria = >2 mL/kg/day
- oliguria = <0.5 mL/kg/day
- anuria = no urine production
What is prognosis of AKI?
- mortality = 50%
- of those that survive, 50% develop CKD
AKI:
