A previously healthy 28-year-old Caucasian woman comes to the physician because of fatigue, arthralgias, and chest pain over the past 6 months. She has had a 2.3-kg (5-lb) weight loss during this period. She denies any recent travel or sick contacts. Her past medical history is insignificant. She takes no medications and has no known drug allergies. She is sexually active and uses condoms for contraception. She has never been pregnant. She does not use tobacco, alcohol, or drugs. Her mother has rheumatoid arthritis. Her temperature is 37.2 C (99 F), blood pressure is 122/77 mm Hg, and pulse is 78/min. Physical examination shows a faint facial rash. The lungs are clear to auscultation with mildly decreased breath sounds at the left lung base. The abdomen is soft and non-tender. There is no organomegaly. There is no peripheral edema. Neurologic examination is unremarkable. Further evaluation reveals a positive antinuclear antibody (ANA) screen in high titers. Other lab studies show: Which of the following antibody titers is most likely to correlate with the disease activity in this patient?

Question

A previously healthy 28-year-old Caucasian woman comes to the physician because of fatigue, arthralgias, and chest pain over the past 6 months.  She has had a 2.3-kg (5-lb) weight loss during this period.  She denies any recent travel or sick contacts.  Her past medical history is insignificant.  She takes no medications and has no known drug allergies.  She is sexually active and uses condoms for contraception.  She has never been pregnant.  She does not use tobacco, alcohol, or drugs.  Her mother has rheumatoid arthritis.  Her temperature is 37.2 C (99 F), blood pressure is 122/77 mm Hg, and pulse is 78/min.  Physical examination shows a faint facial rash.  The lungs are clear to auscultation with mildly decreased breath sounds at the left lung base.  The abdomen is soft and non-tender.  There is no organomegaly.  There is no peripheral edema.  Neurologic examination is unremarkable.   Further evaluation reveals a positive antinuclear antibody (ANA) screen in high titers.  Other lab studies show:  Which of the following antibody titers is most likely to correlate with the disease activity in this patient?

Quizplus · Accepted Answer

Explanation: This patient's high-titer ANA and mild cytopenia further support a diagnosis of systemic lupus erythematosus (SLE). Anti-dsDNA antibodies are helpful to confirm a diagnosis of SLE, but are also useful to follow the course of disease. In some patients, titers of anti-dsDNA antibodies correlate with disease activity. Anti-dsDNA antibody levels have also been associated with the development of lupus nephritis-immune complexes containing these antibodies are actually seen within the glomeruli of patients with lupus nephritis. Rising titer levels of anti-dsDNA antibodies can be helpful in confirming that the underlying lupus is the cause of a clinical problem as opposed to infection, medication toxicity, or unrelated disease. (Choice B) Anti-centromere antibodies are usually seen in scleroderma-not SLE. (Choice C) Anti-mitochondrial antibodies are associated with primary biliary cirrhosis (PBC), and levels are usually stable in a given patient over time. (Choice D) Anti-Smith antibodies do not correlate with disease activity in SLE patients. However, they are highly specific for SLE and may remain positive in patients with clinically-improving SLE when anti-dsDNA antibodies have returned to the normal range. (Choice E) A positive anti-Ro/SSA antibody test has been correlated with a butterfly photosensitivity rash and other cutaneous manifestations of SLE as well as interstitial lung disease and congenital heart block. However, it is not considered as reliable as anti-dsDNA antibodies. Educational objective: Anti-dsDNA antibodies can be used to follow disease activity in SLE patients and is associated with the development of lupus nephritis. References: Predictive value of autoantibodies for activity of systemic lupus erythematosus. (http://www.ncbi.nlm.nih.gov/pubmed/15230281)

A Previously Healthy 28-Year-Old Caucasian Woman Comes to the Physician