A 32-year-old woman with systemic lupus erythematosus comes to the office for a follow-up visit. The patient was diagnosed with lupus 3 years ago during evaluation of a skin rash and joint pain, and her symptoms have been well controlled with hydroxychloroquine. She takes no other medications, has no other medical conditions, and does not use tobacco, alcohol, or illicit drugs. Blood pressure is 150/90 mm Hg and was normal during previous office visits. Temperature is 37.2 C (99 F), pulse is 78/min, and respirations are 14/min. There is a faint malar rash but no mucosal ulcers, joint tenderness, or swelling. The lungs are clear on auscultation and heart sounds are normal with no murmur, rub, or gallop. The abdomen is soft and nontender with no hepatosplenomegaly. There is mild pitting edema of the bilateral lower extremities. Neurologic examination shows no abnormalities. Laboratory results are as follows:
The patient's serum chemistry and urinalysis were within normal limits 2 months ago. Renal ultrasonography shows normal-sized kidneys with no hydronephrosis.
Renal biopsy reveals diffuse lupus nephritis (Class IV) and appropriate therapy is initiated. Which of the following is most appropriate for monitoring the renal disease activity in this patient?

Question

A 32-year-old woman with systemic lupus erythematosus comes to the office for a follow-up visit.  The patient was diagnosed with lupus 3 years ago during evaluation of a skin rash and joint pain, and her symptoms have been well controlled with hydroxychloroquine.  She takes no other medications, has no other medical conditions, and does not use tobacco, alcohol, or illicit drugs.  Blood pressure is 150/90 mm Hg and was normal during previous office visits.  Temperature is 37.2 C (99 F), pulse is 78/min, and respirations are 14/min.  There is a faint malar rash but no mucosal ulcers, joint tenderness, or swelling.  The lungs are clear on auscultation and heart sounds are normal with no murmur, rub, or gallop.  The abdomen is soft and nontender with no hepatosplenomegaly.  There is mild pitting edema of the bilateral lower extremities.  Neurologic examination shows no abnormalities.  Laboratory results are as follows:
 The patient's serum chemistry and urinalysis were within normal limits 2 months ago.  Renal ultrasonography shows normal-sized kidneys with no hydronephrosis.
Renal biopsy reveals diffuse lupus nephritis (Class IV) and appropriate therapy is initiated.  Which of the following is most appropriate for monitoring the renal disease activity in this patient?

Quizplus · Accepted Answer

Explanation: Renal involvement in systemic lupus erythematosus (SLE) is due to immune complex-mediated glomerular injury. These immune complexes are composed primarily of anti-double stranded DNA (anti-dsDNA) antibodies and are deposited in the mesangial, subendothelial, or subepithelial space, with resultant influx of neutrophils and mononuclear cells. The titers of anti-dsDNA correlate well with the disease activity of lupus nephritis. Of note, anti-dsDNA is also highly specific for SLE. Immune complex deposition within the glomerulus induces complement fixation, leading to low circulating complement levels. Complement activation occurs during active disease, so low levels correlate well with disease activity. (Choices A, C, and D) There is an association between the presence of anti-Smith antibodies and renal disease, but anti-Smith antibodies remain elevated even when the disease is no longer active, making them unsuitable for monitoring disease activity. These antibodies may be useful for identifying patients at risk of developing renal dysfunction and should be monitored closely. Anti-Smith antibodies are highly specific for SLE. (Choice B) Serum antinuclear antibody titers are sensitive but not specific for SLE; however, they do not correlate to active disease or renal involvement. Educational objective: Anti-double stranded DNA and complement levels can be used to monitor for active renal involvement in patients with systemic lupus erythematosus. Antinuclear antibody titers do not correlate with renal disease activity.

A 32-Year-Old Woman with Systemic Lupus Erythematosus Comes to the Office