Acute Kidney Injury (AKI) Overview
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Questions and Answers

What is the term currently favored over "renal failure"?

  • End-stage renal disease
  • Kidney injury (correct)
  • Nephrotic syndrome
  • Glomerulonephritis

Which of the following is NOT considered a cause of decreased glomerular filtration rate (GFR)?

  • Renal obstruction
  • Decreased number of functioning nephrons
  • Increased renal perfusion (correct)
  • Prerenal disease

What is the primary characteristic of prerenal disease?

  • Blockage in the urinary tract
  • Reduced blood flow to the kidneys (correct)
  • Inadequate production of erythropoietin
  • Damage to the nephrons

A patient with acute renal failure is at risk of what electrolyte imbalance?

<p>Hyperkalemia (A)</p> Signup and view all the answers

Which of the following is a potential consequence of impaired hormone production due to loss of functioning nephrons?

<p>Anemia (B)</p> Signup and view all the answers

What percentage of nephrons must be affected before significant functional impairment is typically observed?

<p>90% (C)</p> Signup and view all the answers

What does uremic syndrome indicate?

<p>Build-up of waste products in the blood (C)</p> Signup and view all the answers

Which of the following is NOT a characteristic of chronic renal failure?

<p>Usually has a rapid onset (A)</p> Signup and view all the answers

What is the primary mechanism by which hypertension contributes to the progression of CKD?

<p>Hypertension leads to increased glomerular hydraulic pressure, causing damage to the glomerulus. (A)</p> Signup and view all the answers

Which of the following is NOT a common cause of Chronic Kidney Disease (CKD)?

<p>Acute kidney injury (C)</p> Signup and view all the answers

In the context of CKD, what is the primary role of parathyroid hormone (PTH)?

<p>PTH promotes calcium absorption in the intestines. (B)</p> Signup and view all the answers

What is the main reason why anemic symptoms develop in patients with CKD?

<p>Decreased production of erythropoietin (A)</p> Signup and view all the answers

Which of the following is a manifestation of CKD-related hyperphosphatemia?

<p>Renal osteodystrophy (B)</p> Signup and view all the answers

How does glomerulonephritis contribute to the initiation of CKD?

<p>By increasing permeability of the glomerular filtration barrier, leading to proteinuria. (A)</p> Signup and view all the answers

What is the primary reason for the increased cardiovascular burden in CKD patients?

<p>Sodium and water imbalance, leading to hypertension. (B)</p> Signup and view all the answers

What is the mechanism behind the development of edema in patients with glomerulonephritis?

<p>Decreased production of albumin, leading to decreased oncotic pressure. (B)</p> Signup and view all the answers

Which of the following is a common treatment for CKD-related hyperphosphatemia?

<p>Phosphate binders (B)</p> Signup and view all the answers

What is the primary role of calcitriol in the regulation of calcium levels?

<p>Calcitriol increases the absorption of calcium in the intestines. (C)</p> Signup and view all the answers

What is a key characteristic of prerenal acute kidney injury (AKI)?

<p>Decreased blood flow to the kidney (B)</p> Signup and view all the answers

Which of the following best describes urinalysis findings indicating prerenal AKI?

<p>Low urine sodium and high urine osmolarity (B)</p> Signup and view all the answers

What type of acute kidney injury is associated with obstruction of urine outflow from the kidney?

<p>Postrenal AKI (C)</p> Signup and view all the answers

In the case of acute tubular necrosis (ATN), which of the following treatment options might not lead to improvement?

<p>Intravenous fluids (B)</p> Signup and view all the answers

What is a common cause of acute tubular necrosis?

<p>Aminoglycoside antibiotics (D)</p> Signup and view all the answers

What laboratory finding is typically observed in patients with acute tubular necrosis?

<p>Presence of granular casts (C)</p> Signup and view all the answers

What role does arginine vasopressin (AVP) play in severe volume depletion?

<p>Reabsorbs water (A)</p> Signup and view all the answers

Renal artery stenosis can lead to hypertension through mechanisms that include:

<p>Increased renin release (C)</p> Signup and view all the answers

When treating renal artery stenosis with an ACE inhibitor, what is a potential risk?

<p>Prevention of Angiotensin II production (A)</p> Signup and view all the answers

How can acute renal failure be defined based on serum creatinine levels?

<p>Increase by over 0.3 mg/dl in 48 hours (A)</p> Signup and view all the answers

A common characteristic of patients with acute renal failure compared to chronic renal disease is:

<p>Reduced time for renal adaptation (A)</p> Signup and view all the answers

What symptom is most likely to develop due to acute renal failure?

<p>Edema (A)</p> Signup and view all the answers

How does sodium retention respond to volume depletion in prerenal disease versus ATN?

<p>Sodium retention is impaired in ATN but normal in prerenal disease. (B)</p> Signup and view all the answers

The histological changes in acute tubular necrosis primarily affect which parts of the nephron?

<p>Proximal tubule and Thick Ascending Loop of Henle (A)</p> Signup and view all the answers

What mechanism causes hyperphosphatemia in chronic renal failure?

<p>Decreased ability of the kidneys to excrete phosphate (B)</p> Signup and view all the answers

How does parathyroid hormone (PTH) affect calcium levels in the body?

<p>Promotes calcium release from bones and reabsorption in the kidneys (D)</p> Signup and view all the answers

What is the primary function of calcitriol in the regulation of calcium?

<p>Increases absorption of calcium in the GI tract (A)</p> Signup and view all the answers

What is a major contributor to the worsening of chronic kidney disease related to hypertension?

<p>Increased intraglomerular pressure leading to glomerular damage (C)</p> Signup and view all the answers

Which factor is primarily responsible for the regulation of phosphate levels in chronic kidney disease?

<p>Decreased renal excretion of phosphate (B)</p> Signup and view all the answers

Which symptom is most likely to indicate acute kidney injury (AKI)?

<p>Rapid development of hyperkalemia and edema (B)</p> Signup and view all the answers

Which factor is NOT typically responsible for causing prerenal acute kidney injury (AKI)?

<p>Urinary tract obstruction (B)</p> Signup and view all the answers

A urine sodium level of 15 mEq/L in a patient with AKI is most indicative of which condition?

<p>Prerenal AKI (D)</p> Signup and view all the answers

What primary mechanism leads to acute tubular necrosis (ATN)?

<p>Direct damage to the tubular epithelial cells (B)</p> Signup and view all the answers

A patient with a GFR of 45 mL/min is classified in which stage of chronic kidney disease (CKD)?

<p>Stage 3 (C)</p> Signup and view all the answers

Which of the following represents an initiating mechanism for chronic kidney disease (CKD)?

<p>Autoimmune attack on the kidney (A)</p> Signup and view all the answers

What is the consequence of renal tubular damage in acute tubular necrosis (ATN)?

<p>Impaired electrolyte balance (B)</p> Signup and view all the answers

In patients with prerenal acute kidney injury (AKI), which laboratory finding is typically observed?

<p>Low urine sodium concentration (A)</p> Signup and view all the answers

Flashcards

Acute kidney injury (AKI)

A sudden and often reversible reduction in kidney function, measured by glomerular filtration rate (GFR).

Prerenal disease

A decrease in blood flow to the kidneys caused by decreased renal perfusion or decreased blood pressure.

Renal obstruction

A blockage in the renal pelvis, ureters, bladder, or urethra causing back pressure on the kidney.

Chronic kidney failure

The process of the kidney losing its ability to filter waste and regulate fluids effectively over time.

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Uremia

A buildup of toxins in the blood, usually seen in kidney failure, leading to various symptoms like fatigue, nausea, and confusion.

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Intrarenal adaptation

The kidneys' ability to adapt internally, making early detection of chronic kidney problems difficult.

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Reduced GFR

A significant functional impairment in kidney function, typically occurring when about 90% of nephrons are affected.

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Glomerular filtration rate (GFR)

The ability of the kidneys to filter blood and regulate fluid balance.

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Diabetic nephropathy

A common cause of CKD involving damage to the tiny filtering units in the kidneys due to uncontrolled high blood sugar.

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Polycystic kidney disease

Disorder characterized by multiple cysts within the kidneys, leading to enlargement and eventual dysfunction.

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Stage 4 CKD

A stage of CKD where the GFR is significantly reduced, but not all kidney function is lost yet.

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Stage 5 CKD

A stage of CKD where the GFR is at the lowest, indicating complete loss of kidney function.

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Hyperkalemia

A possible symptom of CKD where the body retains too much potassium.

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Uremic symptoms

A sign of CKD due to buildup of waste products in the body, often associated with inflammation of a heart sac.

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Hyperfiltration by remaining nephrons

A process that contributes to CKD progression where remaining healthy nephrons work harder, leading to further damage.

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Glomerulonephritis

Occurs when inflammation of the glomerulus damages the filtering unit, leading to protein in the urine and decreased plasma oncotic pressure.

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Erythropoietin

A hormone produced by the kidneys, essential for red blood cell production, often decreased in CKD, leading to anemia.

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PTH secretion in a normal individual

The process of the parathyroid glands secreting parathyroid hormone (PTH) in response to low calcium levels.

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What is the KDIGO definition of Acute Kidney Injury (AKI)?

An increase in serum creatinine by over 0.3 mg/dl within 48 hours, or a 50% increase in serum creatinine compared to baseline within 7 hours, or a urine volume less than 0.5 ml/kg/hr for 6 hours.

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What is Postrenal AKI?

Obstruction of urine flow from the kidney caused by blockages like clots, stones, tumors, or enlarged prostate.

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What is Prerenal AKI?

Decreased blood flow to the kidney due to low pressure or volume, leading to reduced kidney function.

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What is Intrinsic/Intrarenal AKI?

Damage to the structures within the kidney, like the nephrons, causing impaired function.

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What is Acute Tubular Necrosis (ATN)?

The most common cause of AKI, where the tubules in the kidneys are damaged.

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What is Renal Artery Stenosis?

A narrowing of the renal artery that can cause high blood pressure.

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What is the key difference between acute renal failure and chronic renal disease?

A temporary but reversible reduction in kidney function caused by decreased blood flow, volume depletion, or kidney damage.

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What is the common causes of Acute Tubular Necrosis (ATN)?

ATN usually arises from ischemia, infection, toxins, contrast dye, or medications, leading to damage to the tubules within the kidney.

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What is an ACE inhibitor?

A medication class specifically designed for treating high blood pressure by blocking the production of angiotensin II, a vasoconstricting hormone.

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How do IV fluids affect the patient with Prerenal disease vs. ATN?

One way to differentiate between prerenal disease and ATN is by administering intravenous fluids. In prerenal disease, fluids will improve the situation due to the lack of fluids being the problem. However, in ATN, fluids might not fix the issue if the damage is not solely due to fluid loss.

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How do Aminoglycoside antibiotics affect the kidneys?

Aminoglycoside antibiotics directly impact tubular epithelial cells, causing damage to tubular structure and function.

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How does the body respond to volume depletion in Prerenal disease vs. ATN?

In severe volume depletion, the body releases AVP (arginine vasopressin) to reabsorb water. However, in ATN this response is diminished due to damage to the nephrons.

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What are the histological changes observed in ATN?

In ATN, tubular necrosis (especially in the proximal tubule and thick ascending loop of Henle) and occlusion of the tubular lumen by epithelial debris are observed.

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What is the difference in the cause of Prerenal disease and ATN?

Prerenal disease is associated with effective volume depletion, while ATN can be caused by volume depletion but also by other factors.

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What is Chronic Kidney Disease (CKD)?

It is a progressive disease that can lead to end-stage renal disease, requiring treatments like dialysis or transplantation.

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What is the hallmark of AKI?

A rapid increase in serum creatinine levels within a short period, often due to reduced blood flow to the kidneys.

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What is Intrinsic AKI?

AKI caused by direct damage to the kidney structures, particularly the nephrons.

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What is the main problem in Prerenal AKI?

Reduced blood flow to the kidneys leading to a decrease in urine output.

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Why is it important to differentiate between Prerenal AKI and ATN?

This is important because it helps us identify the cause of the kidney problem and determine the most appropriate treatment.

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What does a low urine sodium level suggest in AKI?

It indicates the body is trying to conserve sodium, which is common in Prerenal AKI.

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What is uremia?

A buildup of waste products in the blood due to failing kidney function, often seen in CKD.

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How does hypertension worsen CKD?

High blood pressure increases pressure within the tiny blood vessels inside the kidneys, leading to damage and worsening kidney function.

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What is the main function of PTH in calcium regulation?

Parathyroid hormone (PTH) increases calcium reabsorption in the kidneys and releases calcium and phosphate from the bones, ultimately increasing calcium levels in the blood.

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What causes hyperphosphatemia in chronic kidney failure?

In chronic kidney disease, the kidneys lose their ability to remove phosphate from the body, leading to increased levels of phosphate in the blood (Hyperphosphatemia).

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What is the role of calcitriol in calcium regulation?

Calcitriol, which is the active form of Vitamin D3, increases the absorption of calcium from the digestive system, ensuring adequate calcium levels are maintained.

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Why does chronic kidney disease often lead to Anemia?

The kidneys are essential in producing erythropoietin, a hormone crucial for red blood cell production. If kidney function declines, erythropoietin production decreases, leading to anemia.

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Study Notes

Acute Kidney Injury (AKI)

  • AKI is a sudden, often reversible decrease in kidney function, measured by glomerular filtration rate (GFR).
  • Not all AKI cases are reversible.
  • Untreated AKI can progress to irreversible chronic kidney disease (CKD).
  • Affects approximately 5% of hospitalized patients, with a high mortality rate if untreated.
  • Rapid development of hyperkalemia and edema is a key sign.
  • Decreased GFR can result from a reduced number of functioning nephrons, prerenal disease, or renal obstruction.
  • Characteristics include rapid development of hyperkalemia and edema

Prerenal AKI

  • Occurs before the blood reaches the kidney.
  • Caused by reduced blood flow to the kidney due to low blood pressure or low blood volume.
  • Characterized by low urine sodium, high urine osmolarity and often improved with intravenous fluids.
  • Decreased renal perfusion and low blood pressure or volume are likely causes.
  • Urinary tract obstruction is NOT a cause.

Postrenal AKI

  • Occurs due to an obstruction of urine outflow from the kidney.
  • Blocks urine pathway causing back pressure on kidneys.
  • Accounts for a small percentage of hospital-acquired AKI cases (about 5%).
  • Common causes include blood clots, kidney stones, cancer, and prostate enlargement.

Intrarenal/Intrinsic AKI (e.g., Acute Tubular Necrosis (ATN))

  • Damage to the structures within the kidney.
  • ATN frequently caused by ischemia, infection, toxins, contrast dyes, certain medications, or interstitial nephritis.
  • ATN can be post-ischemic or toxic.
  • Characterized by tubular necrosis (damage to kidney tubules) and blockage of the tubules by debris.
  • GFR can be significantly reduced in ATN.
  • Differentiation from prerenal AKI can be challenging; IV fluids may or may not improve the situation depending on the underlying cause.
  • Direct damage to tubular epithelial cells is the primary mechanism.
  • In prerenal, decreased kidney perfusion is the problem; IV fluids help address this, raising GFR. In ATN, the problem is often structural, and IV fluids are less effective.

Chronic Kidney Disease (CKD)

  • CKD is a progressive and irreversible decrease in kidney function over time.
  • Common causes include diabetic nephropathy, chronic glomerulonephritis, polycystic kidney disease, and hypertensive nephrosclerosis.
  • Stages are determined by GFR levels, with stage 5 being end-stage renal disease (ESRD).
  • CKD can lead to complications including electrolyte imbalances (sodium and potassium), uremic symptoms, coagulation problems, anemia, acid-base imbalances, and bone disease.
  • GFR levels can be used to determine stage.
  • Initiation mechanisms include underlying causes like autoimmune attacks.
  • Progressive mechanisms contribute to worsening, such as increased intraglomerular pressure from hypertension.

CKD Progression Mechanisms

  • Initiation Mechanisms: specific to underlying cause (e.g., inflammation, autoimmune response).
  • Progressive Mechanisms: Hyperfiltration and hypertrophy of remaining nephrons and hypertension. This increases pressure in the glomeruli further damaging them.
  • Example Causes: Glomerulonephritis damages glomerular barrier leading to proteinuria; polycystic kidney disease (PKD) causes cyst growth, replacing healthy kidney tissue.

CKD and Renal Regulation of Calcium

  • CKD disrupts calcium and phosphate regulation, often leading to imbalances resulting in PTH (parathyroid hormone) elevation.
  • High PTH levels lead to issues with bone health.
  • Kidney failure leads to decreased calcium reabsorption; phosphate retention.
  • Significant calcium phosphate imbalances can cause complications including renal osteodystrophy and metastatic calcification.
  • Treatments aim to reduce phosphate levels and regulate PTH.
  • Hyperphosphatemia occurs due to impaired kidney excretion of phosphate.

Renal Artery Stenosis

  • This narrowing of renal artery causes hypertension, either through:

    • Increased renal resistance and volume retention.
    • Baroreceptors and macula densa triggering renin release and Angiotensin II production

  • Treatment with ACE inhibitors can worsen AKI in this situation by preventing the constriction of the efferent arteriole, leading to decreased glomerular filtration pressure.

Additional Key Facts

  • Urine sodium level of 15 mEq/L is consistent with prerenal AKI.
  • A GFR of 45 mL/min indicates Stage 3 CKD.
  • Calcitriol increases calcium absorption in the GI tract.

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Description

This quiz provides an overview of Acute Kidney Injury (AKI), exploring its causes, types, and potential effects on kidney function. Learn about prerenal and postrenal AKI, their characteristics, and the importance of timely intervention. Test your knowledge on this critical topic in renal health.

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