Differential Diagnosis for AKI Superimposed on CKD

Single Most Likely Diagnosis

• Acute Tubular Necrosis (ATN): This is a common cause of AKI, especially in patients with pre-existing CKD, often due to ischemia or nephrotoxicity from medications or contrast agents.

Other Likely Diagnoses

• Prerenal AKI: Conditions such as dehydration, heart failure, or liver disease can lead to decreased renal perfusion, causing AKI in the setting of CKD.
• Postrenal AKI: Obstruction of the urinary tract, which can be more common or have more significant consequences in patients with CKD, leading to AKI.
• Medication-induced nephrotoxicity: Many medications, including NSAIDs, certain antibiotics, and antifungals, can cause AKI, especially in patients with underlying CKD.

Do Not Miss Diagnoses

• Sepsis: A life-threatening condition that can cause AKI and is critical to identify and treat promptly.
• Rapidly Progressive Glomerulonephritis (RPGN): Although less common, RPGN can lead to rapid deterioration of renal function and requires immediate attention.
• Atheroembolic disease: Especially in patients with a history of vascular disease or recent vascular procedures, this condition can cause AKI and has significant implications for management.

Rare Diagnoses

• Vasculitis: Conditions such as ANCA-associated vasculitis or lupus nephritis can cause AKI in the setting of CKD but are less common.
• Thrombotic Microangiopathy (TMA): Including conditions like thrombotic thrombocytopenic purpura (TTP) or hemolytic-uremic syndrome (HUS), which are rare but critical to diagnose due to their specific treatments.
• Infiltrative diseases: Such as amyloidosis or sarcoidosis, which can affect the kidneys and cause AKI in patients with CKD, though they are less frequently encountered.