AKI Flashcards
[AKI EPID] Increases in SCr as low as ____ mg/dL are linked to a fourfold increase in hospital mortality.
0.3
______ (from “azo,” meaning nitrogen, and “-emia,” meaning in the blood) is the most common form of AKI.
Prerenal azotemia
The most common clinical conditions associated with prerenal azotemia are hypovolemia, decreased cardiac output, and medications that interfere with renal autoregulatory vascular responses such as _______
nonsteroidal anti-inflammatory drugs (NSAIDs)
inhibitors of angiotensin II
Renal blood flow accounts for ____ of the cardiac output
20%
Renal autoregulation usually fails once the systolic blood pressure falls below ___ mmHg.
80
_____ inhibit renal prostaglandin production, limiting renal afferent vasodilation.
NSAIDs
____ limit renal efferent vasoconstriction;
Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs)
Which of the following is the most common cause of prerenal azotemia?
A) Intrinsic renal parenchymal disease
B) Decreased renal plasma flow and glomerular hydrostatic pressure
C) Postrenal obstruction
D) Nephrotoxic drug exposure
B
Which medication combination poses the highest risk for developing prerenal azotemia?
A) NSAIDs with loop diuretics
B) NSAIDs with ACE inhibitors or ARBs
C) Proton pump inhibitors with calcium channel blockers
D) Diuretics with beta blockers
B
The most common causes of intrinsic AKI are _____, ischemia, and nephrotoxins, both endogenous and exogenous
sepsis
The kidneys are also the site of one of the most hypoxic regions in the body, the _____
renal medulla
______ has been associated with development of nephrogenic systemic fibrosis (NSF) in subjects with advanced kidney disease, but the majority of these cases were associated with group I gadolinium-based contrast media,
Gadolinium
Risk factors for nephrotoxicity include _____, CKD, and prerenal azotemia.
older age
The most common clinical course of contrast nephropathy is characterized by a rise in SCr beginning _____ following exposure, peaking within ____, and resolving within ____
24–48 h
3–5 days
1 week
_____ are commonly used drugs that have been associated with acute tubulointerstitial nephritis.
Proton pump inhibitors and NSAIDs
Criteria for AKI Diagnosis:
Serum Creatinine (SCr):
~Increase of ____mg/dL within 48 hours.
~Increase of ≥50% from baseline within _____
Urine Output:
~<0.5 mL/kg/h for____hours.
≥0.3
1 week
> 6
AKI is a frequent complication in patients with CKD T/F
T
Which of the following findings in the history is most suggestive of prerenal azotemia?
A) Nocturia and urinary hesitancy
B) History of vomiting and diarrhea
C) Recent initiation of nephrotoxic antibiotics
D) Colicky flank pain radiating to the groin
B
A patient presents with AKI and a history of prostatic disease. Which symptom is most likely to indicate postrenal AKI?
A) Orthostatic hypotension and dry mucous membranes
B) Suprapubic pain and abdominal fullness
C) Fever and pruritic rash
D) Hypertension and proteinuria
B
A history of prostatic disease, nephrolithiasis, or pelvic or paraaortic malignancy would suggest the possibility of postrenal AKI.
A reduction in urine output (oliguria, defined as ____mL/24 h)
<400
Oliguria denotes more severe AKI and is associated with worse clinical outcome T/F
T
Which of the following urine findings is most characteristic of acute tubular necrosis (ATN)?
A) Hyaline casts
B) Dysmorphic red blood cells
C) Pigmented “muddy brown” granular casts
D) Calcium oxalate crystals
C
A patient with AKI presents with red or brown urine that persists in the supernatant after centrifugation. What is the most likely diagnosis?
A) Hematuria from glomerulonephritis
B) Pigment nephropathy from rhabdomyolysis
C) Uric acid nephropathy
D) Postrenal AKI from obstructive uropathy
B
Red or brown urine persisting in the supernatant after centrifugation suggests the presence of myoglobin or hemoglobin, as seen in rhabdomyolysis or hemolysis.
Which of the following urine findings suggests glomerulonephritis as the cause of AKI?
A) Dysmorphic red blood cells and red blood cell casts
B) White blood cell casts and pyuria
C) Oxalate crystals and acidic pH
D) Hyaline casts and bland sediment
A
In a patient with suspected ethylene glycol poisoning, which urine finding would support the diagnosis?
A) Uric acid crystals
B) Oxalate crystals
C) Amorphous phosphates
D) White blood cell casts
B
What is the most likely urine sediment finding in prerenal azotemia?
A) Pigmented granular casts
B) Hyaline casts
C) White blood cell casts
D) Dysmorphic red blood cells
B
Hyaline casts or an unremarkable urine sediment is typical in prerenal azotemia, reflecting concentrated urine without intrinsic kidney damage.
What is the most likely urine sediment finding in interstitial nephritis?
A) Pigmented granular casts
B) Hyaline casts
C) White blood cell casts
D) Dysmorphic red blood cells
C
Contrast nephropathy leads to a rise in SCr within 24–48 h, peak within ____ days, and resolution within 5–7 days.
3–5
The rise in SCr is characteristically delayed for 3–5 days to 2 weeks after initial exposure.
Aminoglycoside
Cisplatin
Marked hyperphosphatemia with accompanying hypocalcemia may suggest _____
rhabdomyolysis or tumor lysis syndrome.
Serum creatine kinase and uric acid levels are often elevated in ____, while tumor lysis syndrome can be associated with normal or marginally elevated creatine kinase and markedly elevated serum uric acid.
rhabdomyolysis
Anti-phospholiase A2 receptor antibodies will point to a diagnosis of _____.
membranous nephropathy
Which of the following is the most useful indicator for differentiating prerenal azotemia from intrinsic AKI?
A) Serum albumin concentration
B) Fractional excretion of sodium (FeNa)
C) Serum calcium level
D) Presence of white blood cell casts in the urine
B
In a patient with prerenal azotemia, what is the expected value of the fractional excretion of sodium (FeNa)?
A) <1%
B) 1–2%
C) >2%
D) Variable depending on diuretic use
A
Which condition could lead to an FeNa >1% despite the presence of hypovolemia?
A) Sepsis-associated AKI
B) Use of diuretics
C) Tumor lysis syndrome
D) Hepatorenal syndrome
B
What should be done if a high suspicion for urinary obstruction persists despite normal findings on initial imaging?
A) Repeat ultrasound with a higher frequency probe
B) Proceed with antegrade or retrograde pyelography
C) Perform a CT scan without contrast
D) Perform MRI with gadolinium-based contrast
B
If a high clinical index of suspicion for obstruction persists despite normal imaging, antegrade or retrograde pyelography should be performed.
In a patient with AKI and enlarged kidneys on imaging, which diagnosis should be considered?
A) Acute interstitial nephritis
B) Chronic kidney disease
C) Hepatorenal syndrome
D) Diabetic nephropathy
A/D
The procedure is most often used in AKI when prerenal azotemia, postrenal AKI, and ischemic or nephrotoxic AKI have been deemed unlikely, and other possible diagnoses are being considered such as glomerulonephritis, vasculitis, interstitial nephritis, myeloma kidney, HUS and TTP, and allograft dysfunction.
Kidney Biopsy
The_____can provide definitive diagnostic and prognostic information about acute kidney disease and CKD.
kidney biopsy
___ and ___ are functional biomarkers of glomerular filtration rather than tissue injury biomarkers and, therefore, may be suboptimal for the diagnosis of actual parenchymal kidney damage.
BUN
creatinine
In oliguric AKI, urine output _____ after intravenous furosemide may identify patients at higher risk of progression to more severe AKI, and the need for renal replacement therapy.
<200 mL over 2h
Urine Microscopy Findings:
Indicators of Severe AKI:
Increased _____
Renal Tubular Epithelial Cells
Granular Casts
_____ is a type 1 transmembrane protein that is abundantly expressed in proximal tubular cells injured by ischemia or multiple, distinct nephrotoxins, such as cisplatin. It can be detected after ischemic or nephrotoxic injury in the urine and plasma
KLM-1
______ is another biomarker of AKI. It can bind to iron siderophore complexes and may have tissueprotective effects in the proximal tubule.
Neutrophil gelatinase associated lipocalin (NGAL, also known as lipocalin-2 or siderocalin)
Buildup of nitrogenous waste products, manifested as an elevated BUN concentration, is a hallmark of AKI.
Uremia
BUN itself poses little direct toxicity at levels ____mg/dL.
<100
_____ is a major complication of oliguric and anuric AKI, due to impaired salt and water excretion.
Expansion of extracellular fluid volume
Recovery from AKI is often heralded by an ______
increase in urine output
The more serious complication of hyperkalemia is due to effects on _____
cardiac conduction, leading to potentially fatal arrhythmias.
The major cardiac complications of AKI are a_____
Arrhythmias, pericarditis, and pericardial effusion
Prolongs QT interval.
Hypocalcemia
IV solution that provides survival benefit
Crystalloid
______ are recommended for patients with AKI who are not hypochloremic;
Buffered crystalloid solutions (e.g., Ringer’s Lactate, Hartmann’s solution, Plasma-Lyte)
______ is recommended for hypovolemic hypochloremic patients if the serum chloride concentration is closely monitored.
0.9% saline
The definitive treatment of the hepatorenal syndrome is _____
orthotopic liver transplantation
AKI due to scleroderma (scleroderma renal crisis) should be treated with ____
ACE inhibitors.
Early and aggressive volume repletion is mandatory in patients with rhabdomyolysis, who may initially require ____ fluid per day.
10 L of
____ in low doses may transiently increase salt and water excretion by the kidney in prerenal states, but clinical trials have failed to show any benefit in patients with intrinsic AKI.
Dopamine
In severe cases of volume overload, ____ may be given as a bolus (200 mg) followed by an intravenous drip (10–40 mg/h), with or without a thiazide diuretic.
furosemide
Metabolic acidosis is generally not treated unless severe (pH ____ and serum bicarbonate ____
<7.20
<15 mmol/L).
______ is common in AKI and can usually be treated by limiting intestinal absorption of phosphate using phosphate binders (calcium carbonate, calcium acetate, lanthanum, sevelamer, or aluminum hydroxide).
Hyperphosphatemia
Measurement of ____ after an AKI episode can help predict the risk of kidney disease progression and can serve as a valuable riskstratification tool.
albuminuria
Which of the following is a characteristic laboratory finding in prerenal azotemia?
A) BUN/creatinine ratio <10
B) FeNa >2%
C) High specific gravity with urine osmolality >500 mOsm/kg
D) Granular casts in the urine sediment
C
Prerenal azotemia is characterized by concentrated urine with high osmolality and specific gravity due to intact tubular function.
Which of the following clinical features is most suggestive of sepsis-associated AKI?
A) History of recent trauma or crush injuries
B) Positive culture from blood or other body fluid
C) Recent exposure to aminoglycosides
D) Normal hemodynamics and low urine output
B
What is the expected FeNa value in early sepsis-associated AKI?
A) FeNa <1%
B) FeNa >2%
C) FeNa between 1–2%
D) FeNa is not useful in this condition
A
FeNa may be low (<1%), particularly early in the course, but is usually >1% with osmolality <500 mOsm/kg
Which of the following urine findings is commonly seen in ischemia-associated AKI?
A) Hyaline casts
B) Granular casts and tubular epithelial cell casts
C) Dysmorphic red blood cells
D) Eosinophils in the urine sediment
B
Which of the following clinical scenarios is most consistent with contrast nephropathy?
A) AKI with a rise in serum creatinine 1–2 days after contrast exposure
B) AKI with FeNa >1%
C) AKI with dysmorphic red blood cells and red blood cell casts
D) AKI with a subacute rise in serum creatinine over 1–2 weeks
A
Which laboratory abnormality is most likely associated with tumor lysis syndrome in AKI?
A) Hypercalcemia
B) Hypophosphatemia
C) Hyponatremia
D) Hyperuricemia
D
What is the typical finding in urine sediment for AKI caused by aminoglycosides?
A) Hyaline casts
B) Tubular epithelial cell casts and granular casts
C) Dysmorphic red blood cells
D) Oxalate crystals
B
“____ HUS” refers to AKI with a diarrheal prodrome, often due to Shiga toxin released from Escherichia coli or other bacteria;
Typical
“____ HUS” is due to inherited or acquired complement dysregulation.
atypical
“___” refers to sporadic cases in adults.
TTP-HUS
Which of the following is a laboratory feature of thrombotic microangiopathies (TTP-HUS) associated with AKI?
A) Hypercalcemia and low albumin
B) Schistocytes on peripheral blood smear and thrombocytopenia
C) Normal LDH and platelet count
D) Hypokalemia and metabolic alkalosis
B
Normal GFR decline: _____ per year from peak (~120 mL/min per 1.73 m² in the third decade).
~1 mL/min
Persistent UACR >2.5 mg/mmol (male) or ____ mg/mmol (female) on two to three occasions serves as a marker not only for early detection of primary kidney disease but for systemic microvascular disease as well.
> 3.5
A ____ has been devised to predict the risk of progression to stage 5 dialysis-dependent kidney disease.
Kidney Failure Risk (KFR) equation
