Acute Renal Infarction Secondary to Atrial Fibrillation: A Rare Cause of Sudden Flank Pain.

Acute renal infarction is an uncommon and often underrecognized cause of sudden flank pain, posing diagnostic challenges due to its nonspecific presentation and laboratory findings. It may manifest with abrupt, severe flank discomfort, nausea, vomiting, and microscopic hematuria, frequently mimicking more common renal or musculoskeletal conditions. Risk factors such as atrial fibrillation significantly increase the likelihood of embolic events leading to segmental renal ischemia, particularly in patients with suboptimal anticoagulation. Imaging, especially contrast-enhanced computed tomography, is pivotal in establishing the diagnosis by identifying characteristic wedge-shaped perfusion defects, while supportive laboratory markers, including elevated lactate dehydrogenase and leukocytosis, may provide additional clues. Prompt recognition and initiation of anticoagulation therapy are central to preserving renal function and preventing further embolic complications. Clinical vigilance, timely diagnostic evaluation, and careful management can result in favorable outcomes, even in patients presenting with acute kidney injury, highlighting the importance of considering renal infarction in the differential diagnosis of sudden flank pain, particularly in those with cardiovascular risk factors.