Compromiso renal en les

Types of renal disease in systemic lupus erythematosus


INTRODUCTION — Renal involvement is common in idiopathic systemic lupus erythematosus (SLE). An abnormal urinalysis with or without an elevated plasma creatinine concentration is present in a large proportion of patients at the time of diagnosis, and may eventually develop in up to 75 percent of cases. The most frequently observedabnormality is proteinuria [1] .

Clinical findings underestimate the true frequency of renal involvement as some patients have significant pathologic abnormalities without any clinical signs of renal involvement. (See "Silent lupus nephritis" below).

There are a number of types of renal disease in SLE, usually differentiated with a renal biopsy, with immune complex-mediated glomerular diseasesbeing most common. In addition, nonlupus renal diseases may be seen [2] .

An overview of the epidemiology and pathogenesis of lupus nephritis and a review of the basic characteristics of the renal diseases associated with SLE are presented here. The indications for renal biopsy and the approach to therapy are discussed separately. (See "Overview of the therapy and prognosis of lupus nephritis"and see "Therapy of diffuse or severe focal proliferative or severe membranous lupus nephritis").

EPIDEMIOLOGY — As mentioned previously, most patients with SLE will have an abnormal urinalysis at some point in the course of their disease.

Clinically evident renal disease occurs in approximately half of the patients with SLE [3-9] . Variations in the prevalence of lupus nephritis may be inpart due to racial differences in disease prevalence and/or risk of nephropathy, as well as definitions and/or disease ascertainment [5,9,10] . The following summarizes the two largest available cohort studies [3,6-8] : Among 1000 consecutive patients from 12 clinical centers in Europe, 16 and 39 percent had nephropathy at diagnosis and by a mean disease duration of eight years, respectively(defined as protein excretion >0.5 g/day [or 3+ on dipstick], cellular casts, or unexplained elevation of the serum creatinine by at least 0.8 mg/dL [75 µmol/L]) [3] . During ten years of prospective follow-up, nephropathy developed in 28 percent; it was unclear whether this represented new cases or recurrent disease [6] . In another report of 1378 patients with SLE in the United States, renal disease(defined as protein excretion >0.5 g/day, ≥ 5 red blood cells per high power field, serum creatinine ≥ 1.5 mg/dL [133 µmol/L], or requiring dialysis or transplant), was present in 32 percent within one year of diagnosis [7] . At a mean disease duration of 9 years, 47 percent had protein excretion >0.5 g/day, and 6 and 4 percent had decreased GFR and end-stage renal disease, respectively [8].

Most renal abnormalities emerge soon after diagnosis (commonly within the first 6 to 36 months) [1,4,11] . Although an elevated plasma creatinine concentration eventually develops in approximately 30 percent of all patients with SLE, evidence of decreased renal function is an uncommon manifestation within the first few years of diagnosis.

The time course for the development of lupusnephritis varies with gender, age, and ethnicity. In a retrospective study in the United States, males, younger patients (eg, less than 33 years of age at diagnosis), and non-European Americans were at enhanced risk of developing nephritis earlier in the course of the disease [4] .

Silent lupus nephritis — Studies in which renal biopsy was performed in patients without any clinical evidence ofrenal disease found mesangial glomerulonephritis or a focal or diffuse proliferative glomerulonephritis in many patients [12-14] . In this setting, the disease often remains clinically silent and is associated with a benign renal outcome. As an example, in a literature review of 213 cases with silent lupus nephritis (half of whom were treated with steroids with or without cyclophosphamide), renal...