Lupus Basics for the Physician Assistant Exam
You will need to know a few things about lupus for the Physician Assistant Exam (PANCE). Systemic lupus erythematosus (SLE), or just plain lupus, is a systemic autoimmune disease that can involve multiple organs and body systems, including the joints, heart and pericardium, lungs, brain (in lupus cerebritis), and kidneys.
As with rheumatoid arthritis, women are affected more than men. You need to be aware of some criteria in making the diagnosis. You don’t need all these criteria to make the diagnosis of systemic lupus erythematosus — four or more will do:
The appearance of a malar (butterfly) rash on the face or a discoid rash
Painful and swollen joints
Evidence of cardiac involvement, including pericarditis; Libman-Sacks endocarditis is a common example
Evidence of kidney disease, including abnormal kidney function, and/or evidence of hematuria and/or proteinuria
Evidence of any neurological involvement
An abnormal complete blood count, including anemia, low platelets, or a low white cell count
Any abnormal antibody testing, including a positive antinuclear antibody (ANA) or low complements, such as a low C3 and C4 (the complements are low because they’re consumed by an overstimulated immune system). Other serologies can include a positive anti-double-stranded DNA (anti-dsDNA) antibody and anti-Smith antibody. The anti-dsDNA is thought to correlate well with evidence of kidney involvement — it rises as the degree of kidney involvement increases.
The treatment for systemic lupus erythematosus can range from steroids and hydroxychloroquine (Plaquenil) to stronger immunosuppressive medications such as methotrexate (Rheumatrex), mycophenolate (Cellcept), and/or cyclophosphamide (Cytoxan). If you see active kidney involvement, give medications such as mycophenolate (CellCept), tacrolimus (Prograf), or cyclophosphamide (Cytoxan) in addition to high-dose prednisone.
In addition to systemic lupus erythematosus (SLE), other types of lupus include discoid lupus erythematosus (DLE) and drug-induced lupus (DIL). Discoid lupus can cause alopecia and scaly, disc-like patches on the skin.
Commonly prescribed medications, including quinidine and hydralazine (Apresoline), can cause drug-induced lupus. You can see an antihistone antibody in the case of drug-induced lupus. In the case of meds like hydralazine, experts think that if a person is a slow acetylator, the risk of drug-induced lupus increases. N-acetylation speed is the rate at which the liver metabolizes the drug.