Bilateral renal artery thrombosis in inherited thrombophilia: a rare cause of acute kidney injury
A 47-year-old male Caucasian farmworker presented with right-sided abdominal pain for the preceding 24 hours. Apart from mild nausea, there were no other associated symptoms. He was known to have antithrombin III deficiency, with functional antithrombin III having been previously quantified at 48% (normal pooled plasma activity 83%–128%). In addition, he was known to be heterozygous for the prothrombin (G20210A) gene mutation. He was taking aspirin 75 mg daily. He had no history of thromboembolism or hypertension. He had no vascular risk factors, including diabetes, dyslipidemia, or a history of smoking.\nOn examination, he was apyrexial. His blood pressure measured 159/88 mmHg. He had right-sided flank tenderness with no rebound or guarding. Bowel sounds were normal. Urine dip revealed 2+ protein but no blood. Creatinine was 1.02 mg/dL (90 μmol/L). Neutrophils were moderately raised at 9.4 × 109/L. CRP (C-reactive protein) was unremarkable at 1.7 mg/L. His pain was managed with paracetamol (acetaminophen) and a single dose of 50 mg diclofenac. Aspirin was withheld and he was given a daily prophylactic dose of enoxaparin 40 mg. Within 24 hours, his abdominal pain had localized to the right iliac fossa and he underwent appendectomy. Intraoperatively, his blood pressure fell to 100/50, requiring intravenous fluid resuscitation. Postoperatively, his abdominal pain settled. He was discharged home the following day with a blood pressure of 125/75 mmHg and a creatinine level of 1.17 mg/dL (103 μmol/L).\nThe patient was readmitted 4 days later with sudden-onset, severe left-sided abdominal pain. He was apyrexial. Blood pressure measured 150/80 mmHg. Examination revealed left-sided abdominal tenderness without rebound or guarding. Bowel sounds were normal. Urine testing revealed new microscopic hematuria. Inflammatory markers were raised with a neutrophil count of 11.7 × 109/L and a CRP level of 43.5 mg/L. Creatinine had increased to 1.62 mg/dL (143 μmol/L). Computed tomography with oral contrast revealed an 85 × 35 mm collection at the appendectomy site. Significant left-sided perinephric stranding was also seen (). He was treated for a postoperative intra-abdominal collection with intravenous co-amoxiclav and metronidazole. Prophylactic enoxaparin 40 mg was given daily. Despite treatment, his inflammatory markers continued to climb, with CRP peaking at 363.9 mg/L. In addition, his hematuria became macroscopic and his renal function declined to a creatinine level of 2.85 mg/dL (252 μmol/L), equating to an estimated glomerular filtration rate (GFR) of 22 mL/min/1.73m2. Anti-neutrophil cytoplasmic antibody (ANCA), double-stranded DNA (dsDNA) and anti-glomerular basement membrane antibody (anti-GBM) were negative. Immunoglobulins were normal and Bence Jones protein was not present in the urine. Nuclear medicine renography confirmed a significant kidney injury, showing a GFR of 21.72 mL/minute. It also demonstrated areas of poor uptake in the right kidney. Computed tomography angiography confirmed large bilateral renal infarcts with occluding thrombus visible in the left renal artery (). Computed tomography and echocardiography excluded left ventricular and aortic thrombi. The patient was commenced on life-long warfarin therapy.\nSix months later, his creatinine had stabilized to 1.98 mg/dL (175 μmol/L), equating to an estimated GFR of 36 mL/min/1.73m2. Blood pressure control required treatment with a combination of three agents. Urinary protein:creatinine ratio measured 698 mg/g and microscopic hematuria persisted.