{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T13:27:17Z","timestamp":1787923637107,"version":"build-2784847793"},"reference-count":22,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T00:00:00Z","timestamp":1787875200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Clin. Med.","JCM"],"abstract":"<jats:p>Background\/Objectives: IgA nephropathy (IgAN) is a highly heterogeneous glomerular disease with variable clinical presentation and response to therapy. Standard histopathology provides a static assessment and may not fully reflect dynamic podocyte injury. The objective of this case series was to characterize distinct clinical phenotypes of IgAN and explore the relationship between urinary protein composition assessed by the urine albumin-to-protein ratio (uAPR) and ultrastructural glomerular injury. Methods: We retrospectively analyzed three patients with distinct clinical phenotypes of biopsy-proven IgA nephropathy to examine the relationship between urinary protein composition (uAPR), ultrastructural findings, treatment response, and clinical outcomes. Results: Case 1 demonstrated a podocytopathic phenotype resembling minimal change disease (MCD) with steroid sensitivity. Case 2 showed progression to focal segmental glomerulosclerosis (FSGS) despite stable renal function. Case 3 revealed persistent predominantly non-albumin proteinuria (uAPR 0.07\u20130.13) preceding biopsy-proven IgAN and resistance to multiple immunosuppressive regimens. Conclusions: Differences in uAPR were observed alongside distinct clinicopathological and ultrastructural phenotypes of IgA nephropathy. These observations suggest that urinary protein composition may provide complementary information on disease phenotype; however, its relationship with specific mechanisms of glomerular injury requires prospective validation.<\/jats:p>","DOI":"10.3390\/jcm15176646","type":"journal-article","created":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T12:27:46Z","timestamp":1787920066000},"page":"6646","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["The Three Faces of IgA Nephropathy: Clinicopathological Heterogeneity and Urinary Albumin-to-Protein Ratio in a Case Series"],"prefix":"10.3390","volume":"15","author":[{"given":"Anna","family":"Masajtis-Zagajewska","sequence":"first","affiliation":[{"name":"Department of Nephrology, Hypertension, Transplantation and Internal Medicine, Central University Hospital, Medical University of Lodz, 90-419 Lodz, Poland"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8013-533X","authenticated-orcid":false,"given":"Blazej","family":"Kieszek","sequence":"additional","affiliation":[{"name":"Department of Nephrology, Hypertension, Transplantation and Internal Medicine, Central University Hospital, Medical University of Lodz, 90-419 Lodz, Poland"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0823-5440","authenticated-orcid":false,"given":"Micha\u0142","family":"Nowicki","sequence":"additional","affiliation":[{"name":"Department of Nephrology, Hypertension, Transplantation and Internal Medicine, Central University Hospital, Medical University of Lodz, 90-419 Lodz, Poland"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"supervision","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1795","DOI":"10.1681\/ASN.2011050464","article-title":"The Pathophysiology of IgA Nephropathy","volume":"22","author":"Suzuki","year":"2011","journal-title":"J. Am. Soc. Nephrol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"268","DOI":"10.1016\/j.kint.2018.10.018","article-title":"Management and Treatment of Glomerular Diseases (Part 1): Conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference","volume":"95","author":"Floege","year":"2019","journal-title":"Kidney Int."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1033","DOI":"10.2215\/CJN.11951113","article-title":"IgA nephropathy with minimal change disease","volume":"9","author":"Herlitz","year":"2014","journal-title":"Clin. J. Am. Soc. Nephrol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1804","DOI":"10.1038\/s41598-025-86081-0","article-title":"Clinical features, pathological characteristics, and prognosis of patients with IgA nephropathy complicated with nephrotic syndrome","volume":"15","author":"Tan","year":"2025","journal-title":"Sci. Rep."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"427","DOI":"10.2215\/CJN.04820511","article-title":"Clinical Features and Outcomes of IgA Nephropathy with Nephrotic Syndrome","volume":"7","author":"Kim","year":"2012","journal-title":"Clin. J. Am. Soc. Nephrol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"469","DOI":"10.2215\/CJN.08600718","article-title":"Proteinuria Reduction as a Surrogate End Point in Trials of IgA Nephropathy","volume":"14","author":"Thompson","year":"2019","journal-title":"Clin. J. Am. Soc. Nephrol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"203","DOI":"10.5414\/CNP65203","article-title":"Mesangial IgA Deposition in Minimal Change Nephrotic Syndrome: Coincidence of Different Entities or Variant of Minimal Change Disease?","volume":"65","author":"Westhoff","year":"2006","journal-title":"Clin. Nephrol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"37","DOI":"10.5414\/CN107682","article-title":"Clinicopathologic Features and Treatment Response in Nephrotic IgA Nephropathy with Minimal Change Disease","volume":"79","author":"Qin","year":"2013","journal-title":"Clin. Nephrol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"567","DOI":"10.1007\/s40620-015-0242-9","article-title":"Long-term Outcome of IgA Nephropathy with Minimal Change Disease: A Comparison between Patients with and without Minimal Change Disease","volume":"29","author":"Li","year":"2016","journal-title":"J. Nephrol."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Li, H., Lu, W., Li, H., Liu, X., Zhang, X., Xie, Y., Lan, P., Yu, X., Dai, Y., and Xie, X. (2021). Immune Characteristics of IgA Nephropathy with Minimal Change Disease. Front. Pharmacol., 12.","DOI":"10.3389\/fphar.2021.793511"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"3720","DOI":"10.1016\/j.ekir.2025.09.032","article-title":"Should Histology Guide Treatment Decisions in IgA Nephropathy?","volume":"10","author":"Selvaskandan","year":"2025","journal-title":"Kidney Int. Rep."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1159\/000516831","article-title":"The Continuing Need for Electron Microscopy in Examination of Medical Renal Biopsies: Examples in Practice","volume":"1","author":"Yamashita","year":"2021","journal-title":"Glomerular Dis."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1014","DOI":"10.1016\/j.kint.2017.02.003","article-title":"Oxford Classification of IgA nephropathy 2016: An update from the IgA Nephropathy Classification Working Group","volume":"91","author":"Trimarchi","year":"2017","journal-title":"Kidney Int."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"S1","DOI":"10.1016\/j.kint.2025.04.004","article-title":"KDIGO 2025 Clinical Practice Guideline for the Management of IgA Nephropathy and IgA Vasculitis","volume":"108","author":"Rovin","year":"2025","journal-title":"Kidney Int."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1534","DOI":"10.1093\/ndt\/gfr708","article-title":"The value of simultaneous measurements of urinary albumin and total protein in proteinuric patients","volume":"27","author":"Smith","year":"2012","journal-title":"Nephrol. Dial. Transpl."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"101259","DOI":"10.1016\/j.xkme.2026.101259","article-title":"The association of urine Albumin to Protein ratio with kidney disease progression","volume":"8","author":"Jaworski","year":"2026","journal-title":"Kidney Med."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Zeng, D., Wang, B., Xiao, Z., Wang, X., Tang, X., Yao, X., Wang, P., Li, M., Dai, Y., and Yu, X. (2024). Early diagnosis and treatment of kidney injury: A focus on urine protein. Int. J. Mol. Sci., 25.","DOI":"10.3390\/ijms252011171"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2332","DOI":"10.1172\/JCI105107","article-title":"Selectivity of Protein Excretion in Patients with the Nephrotic Syndrome","volume":"43","author":"Joachim","year":"1964","journal-title":"J. Clin. Investig."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"656","DOI":"10.1177\/0961203316676383","article-title":"Proteinuria selectivity index as a prognostic biomarker in lupus nephritis","volume":"26","author":"Hasegawa","year":"2017","journal-title":"Lupus"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"371","DOI":"10.1007\/BF01453654","article-title":"Sodium dodecyl sulphate polyacrylamide gel electrophoresis patterns of proteinuria in various renal diseases of childhood","volume":"5","author":"Brocklebank","year":"1991","journal-title":"Pediatr. Nephrol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1197","DOI":"10.34067\/KID.0000000000000499","article-title":"Minimal change disease and FSGS are a spectrum of a single disease within immune-mediated nephrotic syndrome","volume":"5","author":"Sim","year":"2024","journal-title":"Kidney360"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"557","DOI":"10.1053\/j.ajkd.2023.08.012","article-title":"The Associations of Urine Albumin\u2013Protein Ratio with Histopathologic Lesions and Clinicopathologic Diagnoses in Individuals with Kidney Disease","volume":"83","author":"Srivastava","year":"2024","journal-title":"Am. J. Kidney Dis."}],"container-title":["Journal of Clinical Medicine"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2077-0383\/15\/17\/6646\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T12:48:08Z","timestamp":1787921288000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2077-0383\/15\/17\/6646"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,28]]},"references-count":22,"journal-issue":{"issue":"17","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["jcm15176646"],"URL":"https:\/\/doi.org\/10.3390\/jcm15176646","relation":{},"ISSN":["2077-0383"],"issn-type":[{"value":"2077-0383","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,28]]}}}