Acute kidney injury with proteinuria in a patient with severe Mitral Stenosis

Background Severe mitral stenosis typically presents with clinical symptoms such as dyspnea, palpitations, fatigue, chest discomfort, orthopnea, and peripheral edema. Paroxysmal atrial fibrillation is sometimes observed and often progresses to persistent atrial fibrillation as the severity of the underlying valvular disease progresses. Case presentation We present a case of mitral stenosis that presented atypically with acute kidney injury and proteinuria. A 50-year-old woman was referred to the Nephrology outpatient clinic for evaluation of proteinuria and hematuria. Laboratory results revealed elevated creatinine (145 µmol/L), haematuria (7 red blood cells), and significant proteinuria (urine protein creatinine ratio 13g/day). Renal ultrasound revealed a smaller left kidney. Review of historical renal imaging indicated a progressive reduction in the size of her left kidney over a period of 2 months. An ultrasound doppler of the renal arteries confirmed reduced blood flow through the left renal artery. A transthoracic echocardiogram was performed following an episode of fluid overload during her inpatient stay, which reported severe mitral stenosis with an area of 1.1 cm². She was incidentally found to have paroxysmal atrial fibrillation during the echocardiogram. The clinical presentation and findings confirmed the diagnosis of renal artery thrombosis secondary to thromboembolism from atrial fibrillation precipitated by mitral stenosis. Conclusion Acute kidney injury accompanied by proteinuria is an atypical manifestation of paroxysmal atrial fibrillation with underlying mitral stenosis and consequent thromboembolism. In younger patients presenting with unexplained acute kidney injury, it is crucial to conduct a comprehensive review of the patient's initial presentation, perform a detailed physical examination, and assess prior imaging studies.