Systemic Lupus Erythematosus

Renal involvement is common in SLE with half of patients having an abnormal urinalysis or a decreased GFR at the time of initial diagnosis, and 75% eventually manifesting kidney disease. Renal involvement includes mild mesangial proliferation, focal or diffuse proliferative glomerulonephritis, membranous glomerulonephritis, and

• 1. The glomerular capillary acts as both a charge and size barrier to the filtration of serum proteins.
• 2. The nephrotic syndrome is manifested by severe proteinuria (>3.0 to 3.5 g/1.73 m²/day) and hypoalbuminemia.
• 3. Patients with the nephrotic syndrome are hyperco- agulable and have an increased incidence of both arterial and venous thrombi.
• 4. Minimal change disease is the most common cause of nephrotic syndrome in children. Proteinuria is selective and the response rate to prednisone is high.
• 5. FSGS is characterized by sclerosis in a portion (segmental) of some (focal) glomeruli. It is the most common primary renal disease causing nephrotic syndrome in African Americans. FSGS can be classified histologically into 5 types.
• 6. Membranous glomerulonephritis is characterized by thickened glomerular capillary walls, the absence of cellular proliferation, and the presence of subepithelial immune deposits. The M-type PLA2R appears to be the human glomerular target antigen in primary membranous glomerulonephritis. Therapy remains controversial because of the high spontaneous remission rate.
• 7. MPGN may present with the nephrotic syndrome, nephritic syndrome, an overlap of these 2 syndromes, or with asymptomatic hematuria and proteinuria. Complement concentrations are low.
• 8. Diabetic nephropathy is the most common cause of the nephrotic syndrome and ESRD in the United States. The natural history of diabetic nephropathy is divided into 5 stages. The rate of progression can be slowed by antihypertensive therapy and tight glucose control.
• 9. Nephrotic syndrome may occur in up to 60% of patients with primary and secondary amyloid. The demonstration of amyloid fibrils on EM is diagnostic.

chronic glomerulonephritis. Although SLE may present as nephrotic syndrome (membranous glomerulonephritis), it more commonly presents as nephritis and is discussed in the following section. Patients may change from 1 form of renal involvement to another.

• NEPHRITIC SYNDROME (GLOMERULONEPHRITIS)

Acute nephritic syndrome or glomerulonephritis is characterized by the abrupt onset of hematuria, proteinuria, and a rise in serum BUN and creatinine concentrations. Patients are often hypertensive and may have peripheral edema. In glomerulonephritis, there is an inflammatory lesion of the glomerular capillary bed that is often immune-mediated. This is manifested clinically by red cell casts, hematuria, and proteinuria. The hallmark of glomerulonephritis on urine microscopy is the presence of dysmorphic red blood cells and red cell casts. Decreased glomerular capillary perfusion decreases GFR and results secondarily in increased reabsorption of sodium and water. Hypertension, oliguria, edema formation, and rising serum BUN and creatinine concentrations are the clinical sequelae.