Renal damage from lupus nephritis (LN) is a significant risk for patients with systemic lupus erythematosus (SLE).1-3 The clinical presentation of LN ranges from mild asymptomatic proteinuria to rapidly progressive glomerulonephritis with hematuria and red cell casts.2 SLE may be confused with several other conditions that include renal involvement, including renal thrombotic microangiopathy, acute tubular necrosis, drug-induced interstitial nephritis, focal segmental glomerulosclerosis, and immunoglobulin A nephropathy.
Early and accurate diagnosis of LN and the initiation of appropriate therapy are critical to minimize the risk for progression to end-stage renal disease. However, the heterogeneity of LN histologic subtypes and the potential confusion with other diseases renders diagnosis based on clinical features alone unreliable and potentially risky, especially given that optimal treatment is determined by LN subtype.2,4,5
In the absence of acute renal failure, it is challenging to establish disease progression and to determine how aggressive treatment must be. The decision to perform biopsy can be complex and differs among physicians. Some clinicians recommend biopsy in patients with proteinuria >500 mg/24 hours, whereas others recommend biopsy for those with proteinuria >1000 mg/24 hours.4
The American College of Rheumatology (ACR) guidelines for the management of LN recommend renal biopsy (unless strongly contraindicated) for all patients with clinical evidence of active LN that has been previously untreated. Renal biopsy is generally recommended in patients with increasing serum creatinine levels without compelling alternative causes (such as sepsis, hypovolemia, or medication).
Renal biopsy is also advised for patients with confirmed proteinuria ≥1000 mg/24 hours, or in patients with proteinuria ≥500 mg/24 hours plus hematuria, defined as ≥5 red blood cells per high power field or proteinuria ≥500 mg/24 hours plus cellular casts.1 In fact, renal biopsy has been shown to be an important tool to support classification and definitive diagnosis of LN histopathologic subtype, assess prognosis, and tailor treatment according to the specific glomerular involvement.1,6
Although renal biopsy is relatively safe and serious complications are uncommon, the risk for bleeding remains a key concern. Other possible adverse events include pain, fistula development, infection, blood vessel or other organ damage, or urine leak. Contraindications for biopsy include the presence of a bleeding diathesis, a solitary kidney, or advanced kidney disease with bilaterally small kidneys.
LN is frequently focal, and therefore adequate tissue sampling is necessary for accurate assessment of glomerular involvement. Limited tissue sample may lead to less accurate interpretation of results.2 Because of these challenges, disagreement persists regarding the appropriate role of renal biopsy in the management and identification of predictors of short- and long-term outcomes.7,8