Renal Infarction in a Young Woman: A Diagnostic Window into Systemic Disease

Introduction: Renal infarction is most commonly seen in older people and the main cause is a cardioembolic event. In young adults renal infarction is more rare and should prompt evaluation beyond common cardiac causes as it may reveal an underlying hypercoagulable state. Case Description: A 45-year-old woman with history of mild proteinuria recognized after preeclampsia had an uneventful course until several years later when she presented with sudden-onset severe left flank pain, low-grade fever, abdominal pain, nausea, vomiting, and headache. She denied rash, joint pain, chest symptoms, or visual changes. Exam was unremarkable. She was on an oral contraceptive containing estrogen. Labs showed: ANA was 1:320; dsDNA positive by ELISA, but negative by IFA. Complements were normal. Lupus anticoagulant, aCL IgG, and B2GPI IgG were elevated (>112 Units, confirmed 3 months later). Urinalysis showed a protein/creatinine ratio 4.6 mg/mg. A CT angiography of the kidneys revealed an area of wedge shaped hypoattenuation in the inferior left renal pole whereas the right kidney appeared normal (figure). Echocardiogram was unremarkable. She was anticoagulated with heparin, then transitioned to warfarin. Her proteinuria improved with a decrease in protein-to-creatinine ratio from 4.66 to 0.20 while on ramipril. A year later, she developed photosensitivity, bilateral carpometacarpal joint pain, low complement C4, lymphadenopathy and a diagnosis of antiphospholipid syndrome was made. Though she did not meet full Systemic Lupus erythematosus (SLE) criteria, hydroxychloroquine was initiated due to evolving features. Discussion: This case highlights renal infarction as the initial presentation of antiphospholipid syndrome. Antiphospholipid syndrome and SLE should part of the differential diagnosis in a young woman with renal infarction.