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109 Cards in this Set
- Front
- Back
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What is acute kidney injury?
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loss of renal function, assessed by GFR over hours to days
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What is the hallmark of acute kidney injury?
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retention of nitrogenous waste products in the blood, often with a reduction in urine volume
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What is azotemia?
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accumulation of nitrogenous waste products in blood
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What is uremia?
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clinical syndrome of symptomatic renal failure
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What are the symptoms of uremia?
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anorexia, nausea, vomiting, muscle cramps, restless legs, sleep disorders, asterixis, mental status changes, seizures, fluid and electrolyte disturbances, anemia, platelet dysfunction, peridcarditis
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What is oliguira?
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low urine volume, lss than 400-500 mL
minimal urine required to excrete the obligate daily solute load at maximal urinary concentration |
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What is anuria?
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24h urine of less than 100 mL
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How does acute kidney injury manifest itself in the blood?
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accumulation of nitrogenous waste products, urea, creatine
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How does acute kidney injury manifest in the ECV?
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sodium and water retention, expansion of ECCV, volume overload by LE/pulmonary edema
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How does acute kidney injury manifest in the kidney?
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decreased excretion of K, H+, phosphate, leads to hyperkalemia, metabolic acidosis, hyperphosphatemia
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What are the potential causes of increased urea in the blood despite preserved GFR due to increased urea generation?
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protein loading, GI bleeding, catabolic steroids like glucocorticoids, tetracycline antibiotics
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What are the potential causes of increased urea in the blood despite preserved GFR due to increased creatinine concentration?
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inhibition of tubular secretion of creatinine by cimetidine or trimethoprim
intereference with assays by cefoxitin or flucytosine |
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What are the prerenal causes of AKI?
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volume depletion, decreased effective blood volume, sepsis, hepatorenal syndrome, severe burns, hypotension, meds
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What are the intrinsic causes of AKI?
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acute tubular necrosis, acute interstitial nephritis, acute glomerulonephritis, acute vascular syndromes, intratubular obstruction
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What are the postrenal causes of AKI?
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intrinsic (kidney stones, papillary necrosis, clot), extrinsic (retroperitoneal fibrosis, malignancy, adenopathy, endometriosis)
lower (BPH, prostate ca, bladder ca, urethral stricture, neurogenic bladder) |
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What is the pathophysiology of prerenal AKI?
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decreased perfusion, reduction in GFR
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How does prerenal AKI look histologically?
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no changes, totally due to hemodynamic problems
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What happens when you have decreased renal perfusion, maintained GFR or prerenal azotemia?
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increased tubular sodium and urea reabsorption
results in low urine sodium concentration, increases plasma urea: creatinine concentration |
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What is hepatorenal syndrome?
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renal vasoconstriction with advanced liver disease
does not reverse with IV volume expansion no intrinsic renal injury |
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What is the clinical history for prerenal AKI?
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acute volume losses (vomiting, diarrhea, acute blood loss), decompensated CHF, liver disease/acute infection, recent history of diuretic use
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What do you find on physical exam with prerenal AKI?
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hypotension, tachycardia, orthostatic BP and pulse, decreased skin turgor, dry mucous membranes and axillae
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What do you find on physical exam with prerenal AKI and volume depletion?
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neck veins will not be distended, lung fields will be clear, minimal/no peripheral edema
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What do you see on physical exam with prerenal AKI and CHF?
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pulmonary rales, S3 cardiac gallop, peripheral edema
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What do you see in patients with prerenal AKI and liver disease?
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ascites and peripheral edema, decreased effective arterial blood volume
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What are the lab findings in prerenal AKI?
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BUN: creatinine ratio > 20:1, elevated urine concentration, bland urine sediment, increased renal tubular sodium reabsorption
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What does increased BUN: creatinine ratio mean?
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passive urea reabsorption from tubule due to decreased tubular fluid flow rate
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What does elevated urine concentration mean?
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hemodynamically mediated vasopressin secretion
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What is fractional excretion of sodium?
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index of renal tubular sodium reabsorption, used to help differentiate between AKI types
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What is the FENa in prerenal kidney injury?
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< 0.01
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What is the FENa normally in ATN?
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0.02
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How do you calculate FENa?
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excreted sodium/filtered sodium
(UNa x V) / (PNa x GFR) (UNa / PNa) / (UCr x PCr) |
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How do you calculate excreted sodium?
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urine sodium x urine volume
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How do you calculate filtered sodium?
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plasma sodium x GFR
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How do you calculate GFR?
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(urine creatinine x V) / plasma creatinine
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How do you treat prerenal AKI?
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correct volume deficits with crystalloid solutions, DQ diuretics and meds that alter intrarenal hemodynamiscs, if underlying heart disease, optimize cardiac function
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What is the pathophysiology of postrenal AKI?
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partial or complete obstruction of UTI between renal pelvis and urethral meatus
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What is the hallmark of obstructive uropathy?
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hydronephrosis
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What is hydronephrosis?
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dilation of the renal collecting system
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What happens if you get partial obstruction of the urinary tract?
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urine flow can be normal, decreased, or increased
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What is the clinical presentation of postrenal AKI?
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frequently with no complaints, anuria, polyuria, fluctuating urine volume
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What are the classic symptoms of bladder outlet obstruction?
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urinary frequency, urgency, intermittency, hesitancy, nocturia, incomplete voiding
hematuria |
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What are the classic symptoms of upper UT obstruction?
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flank pain
hematuria |
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What do you see in labs for postrenal AKI?
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bun: creatinine ratio, unremarkable urine sediment, microscopic hematuria with no casts, variable urine chemistries
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What do you do to diagnose postrenal AKI?
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post-void residual bladder volume > 100 mL
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How do you do a postrenal residual bladder volume?
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place a bladder catheter or ultrasound to measure residual bladder volume after patient voids
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When do you use radiology for AKI?
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upper tract
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What kind of radiologic study should you use initially for a postrenal AKI?
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renal ultrasound
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What od you use initiallly for identifying kidney stones?
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CT scan
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Why would you use an antegrade nephrostogram?
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accompanied by placement of percutaneous nephrostomy for treatment
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How do you treat postrenal AKI?
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relieve obstruction, monitor closely for volume depletion, treat with IVF
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What else do you do for a lower tract obstruction?
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bladder catheter
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What else do you do for an upper tract obstruction?
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ureteral stent or percutaneous nephrostomy
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Why do you get post-obstructive diuresis with postrenal AKI?
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excretion of excess salt and water retained during obstruction, from urea diuresis as azotemia resolves, from renal salt wasting caused by tubular injury becasue of the obstruction, from nephrogenic diabetes insipidus caused by the obstruction
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What is the most common form of intrinsic acute kidney injury?
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acute tubular necrosis
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What is the pathophysiology of ATN?
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widespread tubular necrosis, tubular obstruction from debris, intense renal vasoconstriction
eventually recover renal function |
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What are the causes of ischemic ATN?
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prolonged prerenal axotemia, hypotension, hypovolemic shock, cardiopulmonary arrest, sepsis
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What drugs can cause nephrotoxic ATN?
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radiocontrast, aminoglycoside antibiotics, amphotericin B, cisplatinum
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What endogenous toxins can cause nephrotoxic ATN?
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hemoglobin, myoglobin
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What is the HPI of ATN?
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acute illnesses, medication, exposure to nephrotoxic episodes of hypotension
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What do you do on physical exam with ATN?
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hemodynamic status, volume status, associated illness
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What is the lab data for ATN?
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BUN: Creatinine < 10:1
oliguric or not isothenuric urine (osmolality around 300) evidence of renal sodium wasting |
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What do you see in urinalysis iwth ATN?
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urine sediment with tubular epithelial cells and epithelial cell casts, and granular casts
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What is the FENa with ATN?
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> 0.02
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How do you treat ATN?
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supportive care
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What is the prognosis for ATN?
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non-oliguric is better, 50% mortality
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What is the clinical presentation of acute interstitial nephritis?
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acute kidney injury accompanied by fever, rash, eosinophilia
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What is the pathophysiology of acute interstitial nephritis?
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presence of lymphocytic infiltrate in the kidney, frequently with eosinophils
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What can cause acute interstitial nephritis?
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drugs, infections, systemic illness
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What drugs can cause acute interstitial nephritis?
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PCN, cephalosporins, NSAIDS, furosemide, rifampin
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What infections can cause acute interstitial nephritis?
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bacterial, viral, rickettsial, TB
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What systemic illnesses can cause acute interstitial nephritis?
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SLE, Sjogren's, tubulointerstitial nephritis and uveitis, sarcoidosis
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What do you see on physical exam with acute interstitial nephritis?
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fever, rash
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What do you see in lab data with acute interstitial nephritis?
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eosniophilia, sterile pyuria, WBC casts, urine eosniophils
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How do you treat acute interstitial nephritis?
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remove underlying trigger, steroids
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How does glomerulonephritis present?
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nephritis urine sediment with hematuria and RBC casts
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What acute vascular syndromes can cause acute kidney failure?
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renal artery thromboemoblism, renal artery dissection, renal vein thrombosis, cholesterol emboli
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What do you see with acute vascular syndromes and renal failure?
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livedo reticularis, micro-infarcts of the digits, needle-shaped clefts in blood vessels
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What is intratubular obstruction?
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uncommon form of acute kidney injury, from crystalline material or calcium oxylate following ethylene glycol ingestion, proteinaceous material
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What is the BUN: Cr in prerenal AKI?
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> 20:1
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What is the FENa in prerenal AKI?
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< 0.01
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What is the urine sediment in prerenal AKI?
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normal
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What is the BUN: Cr in postrenal AKI?
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> 20:1
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What is the FENa with postrenal AKI?
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variable
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What is the UNa with prerenal AKI?
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< 20
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What is the urine sediment with postrenal AKI?
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normal or RBCs
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What is the BUN: Cr with intrinsic ATN?
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<10:1
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What is the UNa with intrinsic ATN?
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>40
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What is the FENa with intrinsic ATN?
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> 2%
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What is the urine sediment with intrinsic ATN?
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muddy brown casts, tubular epithelial cells
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What is the BUN: Cr with AIN?
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< 20:1
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What is the UNa with AIN?
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> 20
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What is the FENa with AIN?
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> 1%
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What is the urine sediment with AIN?
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WBCs, WBC casts, RBCs, eosinophils
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What is the BUN: Cr with AGN?
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variable
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What is the UNa with AGN?
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<40
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What ist he FENa with AGN?
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<1%
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What is the urine sediment with AGN?
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RBCs, RBC casts
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What ist he BUN: Cr with vascular AKI?
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variable
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What is the UNa with vascular AKI?
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>20
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What is the FENa with vascular AKI?
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variable
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What is the urine sediment with vascular AKI?
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normal or RBCs, eosinophils in atheroembolic disease
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What is the BUN: Cr with intratubular obstruction?
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variable
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What is the UNa with intratubular obstruction?
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variable
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What is the FENa with intratubular obstruction?
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variable
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What is the urine sediment with intratubular obstruction?
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crystals or presence of immunoglobulin light chains in the urine
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How do you treat acute kidney injury?
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fluid management, diuretics, bicarb supplementation, K, phosphate restriction and phosphate binders
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What are the indications for renal replacement in AKI?
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acidosis unresponsive to alkali replacement
electrolyte disturbances ingestions overload of volume unresponsive to diuretics uremic symptoms like pericarditis and encephalopathy |
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What is the FENa with AGN?
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< 1%
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What is the urine sediment with AGN?
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RBCs, RBC casts
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