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Symptoms and Diagnosisof IgA Nephropathy

Recognizing IgA nephropathy: From symptom onset to diagnosis

IgA nephropathy has a variable clinical presentation and heterogeneous disease course, with differing levels of risk for progressive kidney function decline among patients.1,2

Prevalent signs and symptoms include:

Persistent proteinuria<sup>1,3,4</sup>

Persistent proteinuria1,3,4

Foamy or frothy urine may occur with proteinuria
Hypertension<sup>1,3</sup>

Hypertension1,3

Many patients present with or develop systemic hypertension, which is considered a sign of kidney involvement and disease progression
Decreased kidney function<sup>3</sup>

Decreased kidney function3

Complications of IgA nephropathy can include the progressive loss of kidney function

Timely recognition of IgA nephropathy is important, because persistent proteinuria, even in patients considered low-risk for disease progression, may precede full clinical presentation, and delayed diagnosis can lead to substantial kidney impairment and eventual failure.4

Diagnostic evaluation of IgA nephropathy

Diagnosing IgA nephropathy requires considerations of risk factors and integration of clinical findings, laboratory testing, and kidney biopsy.1,3

Symptoms may not appear for years or even decades, with early disease frequently clinically silent.3,5 When patients seek medical care, their diagnoses are often delayed, leading to more advanced disease at diagnosis.5

Risk factors for disease progression include:

  • Persistent proteinuria1: Proteinuria ≥0.5 g/d is associated with increased risk of disease progression. Proteinuria targets should be maintained at <0.5 g/d at a minimum, but ideally at <0.3 g/d
  • Decreased estimated glomerular filtration rate (eGFR)1,6: Patients with decreased eGFR (<60 mL/min per 1.73 m2) are at higher risk of progression to end stage kidney disease (ESKD). The goal of treatment is to slow kidney function decline to <1 mL/min per year
  • Hypertension6

Common laboratory assessments used include:

Urine protein-to-creatinine ratio (UPCR) from a spot urine sample3,7,8

24-hour urine protein collection8

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Serum albumin7

eGFR and serum creatinine9

Microscopic hematuria6,10

Although clinical and laboratory findings can identify potential patients with IgA nephropathy, it can only be confirmed with a kidney biopsy.1,3

Kidney biopsy: Confirming the diagnosis

According to the Kidney Disease: Improving Global Outcomes (KDIGO) 2025 IgAN Guideline, the only way to definitively diagnose IgA nephropathy is with a kidney biopsy.1 Kidney biopsy is recommended in adults with proteinuria ≥0.5 g/day (or equivalent) when IgA nephropathy is suspected and no contraindications for biopsy are present.1

Biopsy is required to identify histopathologic evidence of active glomerulonephritis, such as mesangial hypercellularity, endocapillary proliferation, and crescents.1,6 A kidney biopsy will help narrow the differential diagnosis (e.g., distinguishing IgA nephropathy from IgA vasculitis).1

Once a diagnosis of IgA nephropathy is made, any secondary causes should be assessed.1
Using clinical laboratory and biopsy findings, the International IgAN Prediction Tools predict the risk of a 50% decline in eGFR or kidney failure up to seven years after biopsy and diagnosis.11 

KDIGO 2025 Clinical Practice Guideline for the Management of Immunoglobulin A Nephropathy (IgAN) and Immunoglobulin A Vasculitis (IgAV) KDIGO 2025 Clinical Practice Guideline for the Management of Immunoglobulin A Nephropathy (IgAN) and Immunoglobulin A Vasculitis (IgAV)
Nephrology IgAN

KDIGO 2025 Clinical Practice Guideline for the Management of Immunoglobulin A Nephropathy (IgAN) and Immunoglobulin A Vasculitis (IgAV)

Learn about updated recommendations on diagnosis, prognosis, treatment, and special situations in IgA nephropathy

Read more

Why early recognition matters

Earlier recognition and diagnosis, along with achieving and maintaining low levels of proteinuria, can reduce disease progression and delay kidney failure in these patients.1,4

Managing IgAN Managing IgAN
Nephrology IgAN

Managing IgAN

Explore how the KDIGO 2025 IgAN Guideline helps inform treatment decisions, long-term management, and prevent immune complex-mediated injury

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Footnotes

eGFR, estimated glomerular filtration rate; ESKD, end stage kidney disease; IgA, immunoglobulin A; KDIGO, Kidney Disease: Improving Global Outcomes; UPCR, urine protein-to-creatinine ratio.

  1. Kidney Disease Improving Global Outcomes (KDIGO). Kidney Int. 2025;108(Suppl 4S):S1-S71.
  2. Barbour S et al. Curr Opin Nephrol Hypertens. 2018;27:214–220.
  3. National Institute of Diabetes and Digestive and Kidney Diseases. Iga Nephropathy. Accessed from: https://www.niddk.nih.gov/health-information/kidney-disease/iga-nephropathy.
  4. Pitcher D et al. Clin J Am Soc Nephrol. 2023;18(6):727-738.
  5. Caster DJ et al. Kidney Int Rep. 2023;8:1792–1800.
  6. Thompson A et al. Clin J Am Soc Nephrol. 2019;14(3):469-481.
  7. Duan et al. Biomark Res. 2024;12(1):72.
  8. Raza A et al. World J Nephrol. 2023;12(5):159-167.
  9. Inker LA et al. Am J Kidney Dis. 2021;78(3):340–349.
  10. Zand L et al. Clin Kidney J. 2023;16:Suppl 2:ii19-ii27.
  11. Haaskjold YL et al. Nephrol Dial Transplant. 2023;38:1183-1191.

MA-DS-26-0035 | May 2026