What is lupus nephritis?

Lupus nephritis is kidney inflammation caused by systemic lupus erythematosus (SLE), the autoimmune disease most commonly known simply as lupus. Roughly half of all people with SLE develop some degree of kidney involvement at some point. Lupus nephritis is one of the more serious manifestations of lupus and is a major reason that early identification and aggressive treatment of lupus matters.

Why kidney involvement is a turning point. Lupus that involves the kidneys carries a higher long-term risk of complications, including chronic kidney disease and end-stage kidney disease requiring dialysis or transplant. Catching kidney involvement early and treating it intensively can prevent or delay these outcomes.

How it is detected. Routine urine testing in people with lupus picks up early kidney involvement before symptoms develop. Protein in the urine (proteinuria), blood in the urine, and a rising creatinine on blood tests are the typical early signs. A kidney biopsy is usually performed to define how active and severe the inflammation is and to classify the type of lupus nephritis (class I through V, with class III and IV being the more severe forms).

The therapy approach. Treatment is typically divided into two phases.

Induction therapy aims to bring the active inflammation under control quickly. Standard induction combines corticosteroids with an immunosuppressant (most commonly mycophenolate mofetil or intravenous cyclophosphamide). Modern practice often adds a third agent (belimumab, an antibody that targets a B-cell survival factor, or voclosporin, an oral calcineurin inhibitor) for additional renal-response benefit.

Maintenance therapy aims to keep the disease quiet over years. This typically uses lower-dose mycophenolate or azathioprine, often with continued belimumab. Hydroxychloroquine is recommended for nearly all SLE patients.

For patients whose disease does not respond well enough, rituximab and obinutuzumab (medicines that deplete B cells, which produce the autoantibodies driving lupus) are options; obinutuzumab is in pivotal data specifically in lupus nephritis. CD19 CAR-T cell therapy is in trials for refractory lupus including lupus nephritis with reports of durable drug-free remission.

What to expect. With modern therapy, most people with lupus nephritis can achieve meaningful improvement in kidney function and stable long-term outcomes. The expanded therapy options in the past several years mean that even patients whose disease was historically difficult to control now have additional pathways. Long-term follow-up with both rheumatology and nephrology is the standard.