09.1 Acute kidney injury

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Questions and Answers

What complication should be closely monitored in patients with acute kidney injury (AKI)?

Hypercalcemia

Hyperlipidemia

Hyponatremia

Hyperkalemia (correct)

Which of the following factors can lead to prerenal acute kidney injury?

Dehydration (correct)

Renal vasoconstriction

Urinary obstruction

Tubular necrosis

Which part of the nephron is most vulnerable to injury during renal acute kidney injury?

Distal convoluted tubule

Collecting duct

Bowman's capsule

Proximal tubule S3 segment (correct)

What is a key diagnostic marker for acute kidney injury?

Serum creatinine Signup and view all the answers

Which nephrons, when obstructed, can lead to postrenal acute kidney injury?

Collecting tubules Signup and view all the answers

Which pharmacological agent is known to cause afferent arteriole constriction, thereby reducing renal perfusion?

NSAIDs Signup and view all the answers

What urinary finding is typical in prerenal acute kidney injury?

Hyaline casts Signup and view all the answers

What vital physiological parameter indicates the failure of autoregulation leading to ischemia in prerenal AKI?

Mean arterial pressure below 75-80 mmHg Signup and view all the answers

What is the primary diagnostic criterion for identifying acute kidney injury (AKI)?

An acute rise in serum creatinine and reduction in urine output Signup and view all the answers

Which of the following best describes prerenal acute kidney injury (AKI)?

Caused by reduced renal perfusion without structural damage, reversible if prompt action is taken Signup and view all the answers

Which condition is most likely to lead to postrenal acute kidney injury (AKI)?

Obstruction of urine flow due to kidney stones or tumors Signup and view all the answers

What mechanism primarily leads to renal acute kidney injury (AKI)?

Direct structural damage to renal tissue affecting nephrons Signup and view all the answers

Which of the following is a key risk factor for developing acute kidney injury (AKI)?

History of chronic kidney disease or heart failure Signup and view all the answers

What treatment option is typically used for prerenal causes of acute kidney injury?

Fluid resuscitation to restore renal perfusion Signup and view all the answers

In managing acute kidney injury, which diagnostic test is NOT typically utilized?

Cholesterol level assessment Signup and view all the answers

Which statement about oliguria is correct in the context of acute kidney injury (AKI)?

Oliguria is characterized by urine output less than 400 mL per day Signup and view all the answers

Study Notes

Acute Kidney Injury (AKI)

AKI is a sudden decrease in kidney function over hours or days, leading to inability to regulate fluids, electrolytes, and acid-base balance.
It can progress to chronic kidney disease (CKD) if not resolved within 3 months.
Diagnosis is based on a rapid rise in serum creatinine and reduced urine output (oliguria).
Early detection improves outcomes.

Learning Objectives

Objective 1: Define AKI and its diagnostic criteria.
Objective 2: Differentiate between pre-renal, renal, and post-renal AKI causes.
Objective 3: Explain the pathophysiological mechanisms in AKI development.
Objective 4: Identify risk factors for AKI and prevention strategies.
Objective 5: Evaluate methods for clinical assessment and management of AKI.

Key Concepts

AKI: Sudden decline in kidney function disrupting fluid-electrolyte balance.
Oliguria: Reduced urine output, often a sign of AKI.
Prerenal AKI: Reduced renal perfusion without structural damage; reversible with restored perfusion.
Renal AKI: Kidney structural damage affecting tubules, glomeruli, interstitium, or vasculature.
Postrenal AKI: Urine outflow obstruction leading to increased pressure and reduced glomerular filtration rate (GFR).

Clinical Applications

Case Study: 70-year-old with heart failure, starting NSAIDs, experiences oliguria and elevated creatinine.
Diagnostic Approach: Assess for volume depletion, nephrotoxic drugs, obstruction symptoms. Include monitoring fluid status, checking creatinine/urea/electrolytes, and renal ultrasound.
Treatment Options: Fluid resuscitation (prerenal), removing nephrotoxins (renal), and treating obstruction (postrenal).
Complications/Management: Monitor for hyperkalemia, metabolic acidosis, and possible need for renal replacement therapy if medical management fails.

Pathophysiology

Prerenal AKI: Hypovolemia, reduced cardiac output, or systemic vasodilation reduce renal perfusion.
Renal AKI: Direct damage to kidney structures, often due to ischemia or nephrotoxins; proximal tubule and thick ascending loop of Henle are vulnerable to ischemia.
Postrenal AKI: Obstruction of urinary outflow increases tubular pressure, reducing GFR and potentially causing irreversible damage if untreated.

Pharmacology

Nephrotoxic Drugs: NSAIDs (constrict afferent arterioles), ACE inhibitors/ARBs (dilate efferent arterioles), aminoglycosides, and radiocontrast agents directly damage tubules or vessels.

Differential Diagnosis

Prerenal: History of dehydration, hypovolemia, heart failure.
Renal: History of drug exposure, systemic illness, or nephrotoxins.
Postrenal: Indicates urinary obstruction, such as flank pain or anuria.

Investigations

Serum Creatinine: Key diagnostic marker for AKI.
Urine Output: Monitor for oliguria (less than 0.5 mL/kg/hour for more than 6 hours).
Urinalysis: Prerenal: Normal sediment; Renal: Muddy brown casts or tubular epithelial cells; Postrenal: Red/white blood cells or crystals.
Imaging: Renal ultrasound to identify postrenal obstruction.

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Description

This quiz covers the essential aspects of Acute Kidney Injury (AKI), including its definitions, diagnostic criteria, and classification into pre-renal, renal, and post-renal causes. Learn about the pathophysiological mechanisms involved, risk factors, and strategies for assessment and management of AKI. Early detection and understanding of AKI are crucial for improving patient outcomes.