Nephrology: Acute Kidney Injury (AKI) & Chronic Kidney Disease (CKD) for USMLE
This module covers two critical nephrology topics essential for USMLE preparation: Acute Kidney Injury (AKI) and Chronic Kidney Disease (CKD). Understanding their pathophysiology, clinical presentation, diagnosis, and management is paramount for success.
Acute Kidney Injury (AKI)
AKI is a sudden decline in kidney function, characterized by an accumulation of waste products in the blood. It's a common complication in hospitalized patients and can lead to significant morbidity and mortality.
An acute rise in serum creatinine and/or a decrease in urine output.
Diagnosis and Management of AKI
Diagnosis involves assessing urine output, serum creatinine, BUN, and electrolytes. Urinalysis can provide clues to the underlying cause. Management focuses on identifying and treating the underlying cause, supportive care (fluid management, electrolyte correction), and avoiding nephrotoxic agents.
Remember the RIFLE criteria (Risk, Injury, Failure, Loss, End-stage renal disease) or KDIGO classification for staging AKI severity.
Chronic Kidney Disease (CKD)
CKD is a progressive loss of kidney function over months or years. It is defined by abnormalities of kidney structure or function, present for more than 3 months, with implications for health.
Common Causes and Complications of CKD
The most common causes of CKD are diabetes mellitus and hypertension. Other causes include glomerulonephritis, polycystic kidney disease, and recurrent pyelonephritis. Complications are widespread and include anemia, mineral and bone disorders, cardiovascular disease, fluid overload, and electrolyte imbalances.
The kidneys filter waste products from the blood and regulate fluid and electrolyte balance. In CKD, this filtering capacity diminishes, leading to a buildup of toxins and imbalances. The nephron, the functional unit of the kidney, becomes progressively damaged. This damage can affect the glomeruli (filtration units), tubules (reabsorption and secretion), and interstitium (supportive tissue). The diagram illustrates the basic structure of a nephron and how damage to its components impairs kidney function.
Text-based content
Library pages focus on text content
| Feature | Acute Kidney Injury (AKI) | Chronic Kidney Disease (CKD) |
|---|---|---|
| Onset | Sudden (hours to days) | Gradual (months to years) |
| Duration | Potentially reversible | Progressive and irreversible |
| Primary Cause | Reduced renal perfusion, nephrotoxins, obstruction | Diabetes, hypertension, glomerulonephritis |
| GFR Change | Rapid decline | Slow, progressive decline |
| Urinary Output | Often decreased | Variable, often decreased in later stages |
Management of CKD
Management aims to slow disease progression, manage complications, and improve quality of life. This includes controlling blood pressure and blood glucose, dietary modifications (low sodium, protein restriction in later stages), managing anemia with erythropoiesis-stimulating agents, treating mineral and bone disorders, and ultimately, renal replacement therapy (dialysis or transplantation) for end-stage renal disease.
Diabetes Mellitus and Hypertension.
Integrating Knowledge for USMLE
For the USMLE, focus on recognizing the clinical scenarios that point to AKI vs. CKD, understanding the key diagnostic markers (creatinine, GFR, albuminuria), and knowing the primary management strategies and common complications for each. Be prepared to differentiate between pre-renal, intrinsic, and post-renal causes of AKI.
Learning Resources
A comprehensive overview of AKI, including causes, pathophysiology, diagnosis, and management, from a trusted medical resource.
Detailed information on CKD, covering its stages, common etiologies, complications, and treatment strategies.
Visual and engaging video lectures explaining the core concepts of AKI and CKD, ideal for visual learners preparing for exams.
An in-depth clinical resource providing evidence-based guidelines for the diagnosis and management of AKI.
A comprehensive guide to the multifaceted management of CKD, including slowing progression and managing complications.
Patient-friendly yet informative resources on kidney disease, including CKD, from a leading non-profit organization.
A detailed review article from the New England Journal of Medicine discussing the complex pathophysiology of AKI.
High-yield video lectures specifically designed for USMLE preparation, covering key nephrology concepts.
Fundamental explanations of kidney function and physiology, crucial for understanding AKI and CKD.
The official clinical practice guideline from KDIGO, providing the most current recommendations for CKD management.