Postpartum Diagnosis of Lupus Nephritis in a Patient with Preeclampsia Presenting with AKI and Decompensated Heart Failure

Introduction: Systemic lupus erythematosus (SLE) is an autoimmune disease that frequently affects women of the childbearing age. Myocarditis complications in SLE are rare and affect less than 10% of patients. Peripartum cardiomyopathy is an idiopathic condition of heart failure. Both diseases can present as acute decompensated heart failure in the postpartum state.We present a unique case of a young woman who presented 6 weeks postpartum with heart failure symptoms and new onset of lupus nephritis. Case Description: A 19-year-old G1P1 woman presented at 6 weeks postpartum with shortness of breath. She underwent induction for delivery at 37-weeks due to significant hypertension and concerns for pre-eclampsia. Physical examination revealed lung crackles, malar rash, and lower extremity edema. A transthoracic echocardiogram showed an ejection fraction of 36-40%. Laboratory work revealed acute kidney injury with serum creatinine 2.9 (normal baseline) and urine protein to creatinine ratio 3 g/g. Urine microscopy revealed dysmorphic red blood cells with acanthocytes. She was initiated on IV furosemide, metoprolol, spironolactone, hydralazine and isosorbide dinitrate for heart failure treatment. Further workup showed positive ANA (1/160), anti-dsDNA (1/640) and anti-histone (7.5 U) antibodies. C3 (28 mg/dL) and C4 (3 mg/dL) levels were low. Hydralazine was discontinued due to the concern for drug-induced lupus. Kidney biopsy resulted as Class IV lupus nephritis. The patient was initiated on systemic steroids and mycophenolate mofetil,then discharged with plans for outpatient follow up. Discussion: Differentiating lupus nephritis versus pre-eclampsia in proteinuric pregnant patients without prior history of SLE can be difficult. This patient was recently diagnosed with pre-eclampsia, now presented with acute decompensated heart failure postpartum. The elevated ANA titer, low complement levels and acute kidney injury made SLE a possible differential diagnosis. Definitive diagnosis was solidified by kidney biopsy showing class IV lupus nephritis. This case highlights the challenging diagnosis of SLE myocarditis in patients presenting with peripartum acute heart failure without history of SLE. Clinicians are required to have a high index of suspicion for SLE in these patients to achieve diagnosis and treatment in a timely manner.