Part 13 - Nephrology Flashcards
True or false: AKI is a clinical diagnosis
True
p. 1799
What is the most common form of AKI?
Prerenal
p. 1799
What type of AKI is due to inadequate renal plasma flow and intraglomerular hydrostatic pressure to support normal GFR?
Prerenal
p. 1799)
What are the most common conditions/causes associated with prerenal azotemia?
Hypovolemia
Decreased cardiac output
Medications (NSAIDS, inhibitors of angiotensin II)
(p. 1800)
True or false: prerenal azotemia involves no parenchymal damage to the kidney
True
p. 1800
True or false: Prerenal azotemia is rapidly reversible once hemodynamics are restored
True
p. 1800
Renal blood flow accounts for how many percent of the cardiac output?
20%
p. 1800
Homeostatic responses occur in response to prerenal azotemia. Mediators of this response include?
Angiotensin II
Norepinephrine
Vasopressin
(p. 1800)
What is the myogenic reflex?
Dilation of the afferent arteriole in the setting of low perfusion pressure to maintain glomerular perfusion
(p. 1800)
What are the compensatory mechanisms involved in prerenal azotemia?
1) Homeostatic responses
2) Myogenic reflex
3) Tubuloglomerular feedback
(p. 1800)
Vasodilators that increase in response to low renal perfusion pressure (in prerenal azotemia)
Prostaglandins (prostacyclin, prostaglandin E2)
Kallikrein and kinins
Nitric oxide
(p. 1800)
What is the tubuloglomerular feedback?
Decreases in solute delivery to the macula dense elicit dilation of the afferent arteriole to maintain glomerular perfusion
(p. 1800)
Renal autoregulation usually fails once the systolic blood pressure falls below ____.
80 mmHg
p. 1800
What is macula densa?
Specialized cells within the distal tubule
p. 1800
What do you call the dilation of afferent arteriole in response to decreased solute delivery to the macula densa?
Tubuloglomerular feedback
p. 1800
Effect of NSAIDs to the kidney
Limits renal prostaglandin production –> limit renal afferent vasodilation
(p. 1800)
Effect of ACE-I and ARBs to the kidney
Limit renal efferent vasocontriction
p. 1800
Which type of hepatorenal syndrome has the poorer prognosis?
Hepatorenal syndrome Type 1
p. 1800
Type of hepatorenal syndrome wherein AKI is seen without an alternate cause persisting despite volume administrate and withholding of diuretics
Hepatorenal syndrome Type 1
p. 1800
Type of hepatorenal syndrome which is characterized mainly by refractory ascites
Hepatorenal syndrome Type 2
p. 1800
True or false: Decreases in GFR with sepsis can occur even in the absence of overt hypotension
True
p. 1801
Segment of the proximal tubule that is metabolically very active
S3 segment
p. 1802
What procedures are most commonly associated with AKI?
Cardiac surgery with cardiopulmonary bypass
Vascular procedures with aortic cross clamping
Intraperitoneal procedures
(p. 1802)
What are common risk factors for postoperative AKI?
Underlying CKD Older age Diabetes Mellitus Congestive heart failure Emergency procedures Longer duration of cardiopulmonary bypass (p. 1802)
How does cardiopulmonary bypass cause AKI (mechanisms)?
1) Extracorporeal circuit activation of leukocytes and inflammatory processes
2) Hemolysis with resultant pigment nephropathy
3) Aortic injury with resultant atheroemboli
(p. 1803)
What is the abdominal compartment syndrome?
Markedly elevated intraabdominal pressures (usually > 20 mmHg) leading to renal vein compression and reduced GFR
(p. 1803)
What do you call markedly elevated intraabdominal pressures (usually above 20 mmHg) that lead to renal vein compression and reduced GFR?
Abdominal compartment syndrome
p. 1803
Microvascular causes of AKI
Thrombotic microangiopathies (APAS, radiation nephritis, malignant nephrosclerosis, TTP-HUS)
Scleroderma
Atheroembolic disease
(p. 1803)
Large vessel diseases associated with AKI
Renal artery dissection Thromboembolism Thrombosis Renal vein compression or thrombosis (p. 1803)
Risk factors for nephrotoxicity
Older age CKD Prerenal azotemia Hypoalbuminemia (p. 1803)
In contrast-induced nephropathy, when does creatinine begin to rise?
24-48 hours after exposure
p. 1803
In contrast-induced nephropathy, creatinine peaks within ____ day/s.
3-5 days
p. 1803
Contrast-induced nephropathy resolves within how many days?
1 week
p. 1803
Mechanisms involved in contrast-induced nephropathy
1) Hypoxia in the renal outer medulla due to perturbations in renal microcirculation and occlusion of small vessels
2) cytotoxic damage to the tubules directly or via the generation of oxygen free radicals
3) transient tubule obstruction with precipitated contrast material
(p. 1803)
AKI secondary to aminoglycosides typically manifest after how many days of therapy?
5-7 days
p. 1803
True or false: AKI secondary to aminoglycosides can present even after the drug has been discontinued.
True
p. 1803
What electrolyte abnormality is a common finding in AKI secondary to aminoglycoside use?
Hypomagnesemia
p. 1803
True or false: Nephrotoxicity from Amphotericin B is dose and duration dependent.
True
p. 1803
Metabolic/electrolyte abnormalities found in AKI secondary to Amphotericin B use
Hypomagnesemia
Hypocalcemia
Non-gap metabolic acidosis
(p. 1803)
AKI secondary to acute interstitial nephritis can occur as a consequence of exposure to what medications?
Penicillins Cephalosporins Quinolones Sulfonamides Rifampin (p. 1804)
What are the renal adverse effects of Ifosfamide?
Hemorrhagic cystitis Type II RTA (Fanconi's syndrome) Hypokalemia Modest decline in GFR (p. 1804)
What is the renal adverse effect of bevacizumab?
Proteinuria
Hypertension via injury to the glomerular microvasculature (thrombotic microangiopathy)
(p. 1804)
Cause of “Chinese herb nephropathy” and “Balkan nephropathy”
Aristolochic acid
p. 1804
What is the most common protein in urine which is produced in the thick ascending limb of the loop of Henle?
Uromodulin
p. 1804
What serum level of uric acid leads to precipitation of uric acid in the renal tubules and AKI?
> 15 mg/dL
p. 1804
Definition of AKI (according to Harrison’s)
1) Rise from the baseline of at least 0.3 mg/dL within 48 hours OR
2) At least 50% higher than baseline within 1 week OR
3) Reduction in urine output to less than 0.5 ml/kg per hour for longer than 6 hours
(p. 1805)
Characteristic urine sediment findings in AKI secondary to ATN
1) Pigmented “muddy brown” granular casts
2) Tubular epithelial cell casts
(p. 1805)
Finding of oxalate crystals in AKI should prompt an evaluation for _____ toxicity.
Ethylene glycol
p. 1805
True or false: Anemia is common in AKI.
True
p. 1807
What is the fractional excretion of sodium (FeNa) in prerenal azotemia?
<1%
Pp. 1806-1807
What is the fractional excretion of sodium (FeNa) in ischemic AKI?
Frequently above 1%
p. 1807
Why is fractional excretion of sodium (FeNa) in ischemic AKI frequently above 1%?
Because of tubular injury and resultant inability to reabsorb sodium
(p. 1807)
Ischemia and nephrotoxin-associated AKI that can present with FeNa < 1%
Sepsis (often early in the course)
Rhabdomyolysis
Contrast nephropathy
(p. 1807)
Causes of RBC or RBC casts in urine
Glomerulonephritis Vasculitis Malignant hypertension Thrombotic microangiopathy (p. 1807, Figure 334-6)
Causes of WBCs or WBC casts in urine
Interstitial nephritis Glomerulonephritis Pyelonephritis Allograft rejection Malignant infiltration of the kidney (p. 1807, Figure 334-6)
Causes of renal tubular epithelial cells (RTE), RTE casts, or pigmented casts in the urine
Acute tubular necrosis Tubulointerstitial nephritis Acute cellular allograft rejection Myoglobinuria Hemoglobinuria (p. 1807, Figure 334-6)