What is the confirmation test for lupus nephritis?

From the Guidelines

The confirmation test for lupus nephritis is a kidney biopsy, as it provides a definitive diagnosis, classification of the disease, and assessment of the severity of inflammation and damage. This invasive procedure involves removing a small sample of kidney tissue, which is then examined under a microscope to confirm the diagnosis, determine the specific class of lupus nephritis (I through VI), and assess the severity of inflammation and damage 1. While blood tests (such as ANA, anti-dsDNA antibodies) and urine tests (showing proteinuria, hematuria, or cellular casts) may suggest lupus nephritis, they cannot definitively diagnose it or classify its type.

Key Points to Consider

• The kidney biopsy results guide treatment decisions, as different classes require different therapeutic approaches, such as aggressive immunosuppressive therapy with medications like cyclophosphamide, mycophenolate mofetil, or rituximab, often combined with corticosteroids 1.
• The biopsy also provides prognostic information by revealing the extent of chronic, irreversible damage versus potentially reversible active inflammation.
• Kidney biopsies should be read by an experienced kidney pathologist and classified according to the International Society of Nephrology (ISN)/Renal Pathology Society (RPS) scheme 1.
• Electron microscopy, where available, is helpful in ascertaining ultrastructural details of histopathology such as the extent and severity of podocyte injury and the location of immune deposits.

Clinical Considerations

• Patients with SLE should be actively and regularly monitored, as the clinical presentation of kidney involvement can remain silent or asymptomatic for a significant period of time 1.
• A holistic assessment including clinical, urinary, and laboratory parameters, and repeated investigations to note the progression of abnormal findings over time, are important in informing clinical management decisions.
• Clinicians should pay attention to the detailed description of both active and chronic histopathologic features affecting different elements of the kidney parenchyma, especially regarding potentially reversible active lesions versus chronic damage not reversible by immunosuppressive medications.

From the FDA Drug Label

The proportion of patients achieving PERR at Week 104 was significantly higher in patients receiving BENLYSTA plus standard therapy compared with placebo plus standard therapy Primary Efficacy Renal Response (PERR) at Week 104 was the primary efficacy analysis; Components of PERR Urine protein:creatinine ratio ≤0.7 g/g eGFR ≥60 mL/min/1.73 m2 or no decrease in eGFR from pre-flare value of >20% Complete Renal Response (CRR) at Week 104 Components of CRR Urine protein:creatinine ratio <0.5 g/g eGFR ≥90 mL/min/1. 73 m2 or no decrease in eGFR from pre-flare value of >10%

The confirmation test for lupus nephritis is not explicitly stated in the provided drug label. However, the label mentions several measures used to assess renal response, including:

• Urine protein:creatinine ratio
• eGFR (estimated glomerular filtration rate)
• PERR (Primary Efficacy Renal Response) at Week 104, which includes components such as urine protein:creatinine ratio ≤0.7 g/g and eGFR ≥60 mL/min/1.73 m2 or no decrease in eGFR from pre-flare value of >20%
• CRR (Complete Renal Response) at Week 104, which includes components such as urine protein:creatinine ratio <0.5 g/g and eGFR ≥90 mL/min/1.73 m2 or no decrease in eGFR from pre-flare value of >10% 2

From the Research

Confirmation Test for Lupus Nephritis

• The confirmation test for lupus nephritis is a renal biopsy, which is considered the gold standard for diagnosis 3, 4, 5, 6.
• Renal biopsy allows for the classification of different forms of autoimmune lupus glomerulonephritis and the detection of other glomerular diseases 3.
• The biopsy findings should be evaluated by dedicated renal pathology services and classified according to the World Health Organization (WHO) system 4.
• Urinalysis is a useful screening test for lupus nephritis, but renal biopsy is necessary for accurate diagnosis and to guide treatment 5.
• Repeat biopsy may be considered when therapy modifications are necessary, such as in cases with incomplete or no response, or when stopping therapy for those in remission 3, 6.