Abstract: SA-PO0895
IgAN with Orthostatic Proteinuria: A Case Report
Session Information
- Glomerular Case Reports: ANCA, IgA, IgG, and More
November 08, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Song, Jiarong, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
- Li, Yifu, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
Introduction
Proteinuria is a key clinical marker in IgA nephropathy (IgAN), serving both as a prognostic indicator and a therapeutic target. Its quantification is essential for risk stratification, guiding treatment decisions, and monitoring disease activity. In this case report, we present a patient with IgAN who exhibited orthostatic proteinuria, highlighting a rare clinical presentation with important diagnostic and management implications.
Case Description
A 41-year-old male with IgAN was referred to our hospital's outpatient clinic. He had been diagnosed with IgAN via renal biopsy 30 months prior at a local hospital, with an Oxford classification of M0E1S0T0C0. Over this period, due to poorly controlled proteinuria, he had been given various treatment regimens on top of RASi support therapy, including steroids, Tacrolimus, leflunomide, hydroxychloroquine, mycophenolate mofetil, ambrisentan, and Tripterygium wilfordii polyglycoside, but his spot urine protein levels remained unsatisfactory.
Upon taking a detailed medical history, we noticed his home urine tests revealed significant daily protein fluctuations. Split-sample measurement showed first morning urine at 45.45 mg/L, but post-travel urine spiked to 3417.76 mg/L. Doppler ultrasound (hilum/aortomesenteric ratio 1.5) didn’t support nutcracker syndrome. SPECT imaging confirmed normal kidney structure, perfusion, and function. Proteinuria variability likely due to other factors.
We thus considered that the patient had IgAN coexisting with orthostatic proteinuria and withdrew immunosuppressive medications, retaining only irbesartan at 150 mg/day. After more than two months, the first morning urine protein level was 67.29 mg/L, and the second spot urine protein level was 255.04 mg/L.
Discussion
This case highlights a rare but clinically significant presentation of orthostatic proteinuria in an adult patient with IgAN. While typically seen in adolescents and young adults. persistent proteinuria despite immunosuppressive therapy prompted further evaluation. Detailed history and split urine collection revealed marked postural variation in urinary protein, confirming orthostatic proteinuria. This case underscores the importance of considering this diagnosis in adult IgAN patients with discordant findings or poor response to treatment. Routine use of split urine collections, especially in patients with variable home test results, can help avoid misdiagnosis and overtreatment.