Which of the following is considered a severe complication of SLE?

Lupus nephritis is considered a severe complication of systemic lupus erythematosus (SLE) because it involves inflammation of the kidneys, which can lead to significant renal damage and compromise kidney function. This condition occurs in a substantial proportion of individuals with SLE and can result in symptoms such as proteinuria, hematuria, and hypertension. If not diagnosed and treated promptly, lupus nephritis can progress to renal failure, requiring dialysis or kidney transplantation, which underscores its severity.

In contrast, while a lupus rash, mild headaches, and fatigue are common manifestations of SLE, they are generally not classified as severe complications. A lupus rash, though potentially distressing, typically does not lead to severe outcomes like organ damage. Mild headaches and fatigue are also common and can often be managed with symptomatic treatments, hence not representing the same level of risk or urgency as lupus nephritis.