UNILATERAL RENAL ARTERY THROMBOSIS PRESENTING WITH ACUTE KIDNEY INJURY: DIAGNOSTIC AND THERAPEUTIC CHALLENGES

Renal artery thrombosis (RAT), characterized by the formation of a thrombus in the main renal artery, is a rare but potentially life-threatening condition associated with significant risk of renal dysfunction. Clinically, RAT is difficult to diagnose and requires radiologic evaluation to confirm the diagnosis. Due to its nonspecific clinical presentation, the condition is often misdiagnosed or diagnosed late. It is estimated that the incidence of renal infarction caused by RAT among patients presenting to the emergency department is less than 0.007%. RAT accounts for only about 1% of all renal injuries. 

A 61-year-old woman with no history of hypertension, diabetes, or malignancy was referred for nephrology consultation due to sudden anuria and rising serum urea and creatinine, while initial haemoglobin and electrolytes were normal. She had a prior history of COVID-19 infection. On admission, vital sign were normal. Physical examination fine rales at the left lung base without edema. On day 2, serum urea rise from 23.3 mg/dL to 59.3 mg/dL and creatinine from 0.65 mg/dL to 2.77 mg/dL; by day 3, urea reached 123.5 mg/dL and creatinine 6.74 mg/dL. Despite rehydration with 500 mL normal saline every 12h, values further increased to 144.1 mg/dL and 7.81 mg/dL, with oliguria and worsening azotemia. Doppler ultrasound demonstrated reduced renal perfusion, and coagulation tests (D-dimer, PT, APTT) were elevated. Abdominal CT angiography revealed distal left renal artery thrombosis extending to the inferior segmental branch with more than 75% renal infarction. The patient underwent three consecutive hemodialysis sessions due to persistent azotemia. Continuous intravenous heparin infusion (10,000 units/24 hours) was started for anticoagulation, followed by percutaneous thrombectomy. After the procedure, urine output returned to normal, and hemodialysis was discontinued. Post-therapy laboratory results showed urea 64.2 mg/dL and creatinine 3.17 mg/dL. Maintenance therapy with warfarin and clopidogrel was given to prevent recurrence. The patient remained stable under anticoagulation and continued regular renal follow-up.

RAT is often associated with atrial fibrillation, atherosclerosis, hypercoagulable states, malignancy, infection, or systemic inflammation1. Occlusion of the main or segmental renal artery branches can cause renal infarction and acute kidney injury. Management is time-sensitive: early heparin anticoagulation and revascularization are essential, with percutaneous endovascular intervention recommended within six hours. In this case, prompt anticoagulation, hemodialysis, and thrombectomy resulted in full renal recovery. Although the etiology was unclear, a previous history of COVID-19 infection may have contributed to the hypercoagulable state leading to RAT. Early vascular imaging is crucial in sudden-onset renal failure with nonspecific laboratory findings². Long-term antithrombotic therapy may prevent recurrence in idiopathic or hypercoagulable conditions2,3.

Renal artery thrombosis is an uncommon but critical cause of acute kidney injury that demands prompt recognition and swift intervention