A case report from Auckland, New Zealand has focussed attention on anticoagulant-related nephropathy (ARN) as an underrecognised cause of acute kidney injury (AKI).
The case [link here] was a 79-year-old man taking the direct-acting oral anticoagulant (DOAC) rivaroxaban as stroke prevention in non-valvular atrial fibrillation. His medical history included CKD, secondary to IgA nephropathy, and hypertension.
The patient presented with a 3-week history of worsening breathlessness associated with gross haematuria, haemoptysis, decreasing urine output and bilateral lower limb oedema.
Initial investigations revealed microscopic haematuria, urine red blood cells >1000 x 106 per high-powered field with red blood cell (RBC) casts, serum creatinine of 950 μmol/L, serum potassium of 7.2 mmol/L and haemoglobin of 77 g/L, the report said.
Radiological studies showed normal-sized kidneys with increased echogenicity and diffuse bilateral infiltrates in the lungs with pulmonary oedema.
“His rivaroxaban was halted, and emergency haemodialysis (HD) was initiated in view of hyperkalaemia and pulmonary oedema.”
The patient was empirically treated with intravenous pulse methylprednisolone followed by oral prednisone, “…considering the high suspicion of pulmonary renal small-vessel vasculitis.”
However vasculitis, hepatitis, immunology and myeloma profile were all negative.
The patient required four HD sessions before his urine output and kidney function improved enough to be able to discontinue the dialysis.
“After correcting his coagulation abnormalities, a kidney biopsy was performed, revealing glomerular and intra-tubular haemorrhage with RBC casts suggestive of ARN,” the study said.
The authors noted that ARN is often underrecognised as a cause of AKI because a kidney biopsy – required for definitive diagnosis – is often avoided “…due to the risk of bleeding associated with anticoagulation or the risk of thrombosis when stopping anticoagulation.”
“AKI is typically attributed to underlying CKD or other concomitant multiple risk factors of AKI, leading to the perception that ARN is rare and, therefore, underestimated,” they said.
The authors noted their patient had a high-risk profile for ARN including older age, male sex, and pre-existing CKD.
They also noted that in two other documented case reports of rivaroxaban-related nephropathy, kidney function failed to recover after supportive treatment, resulting in permanent dialysis dependence.
“Cessation and reversal of anticoagulation remain the cornerstone of successful treatment. Our patient received short-term treatment with steroids, which might have contributed to improvement in his kidney function,” they said.
“This report highlights the importance of caution in prescribing oral anticoagulants, even DOACs, in high-risk patients, especially those with advanced CKD…,” they concluded.
The case report was published in the Internal Medicine Journal [link here].