Diagnosis
-H&P. Med review for meds known to cause drug-induced lupus.
-Need ≥4 of 11 ACR criteria to diagnose SLE. Having ≥4 criteria diagnoses SLE with 95% specificity and 85% sensitivity (AFP).
–Algorithm for the diagnosis of SLE from the AAFP
-H&P (esp. skin, joints, liver/spleen, and CV to look for a pericardial rub or murmurs).
–Labs: CBC, CMP, CK, ANA (1st-line test), ESR, CRP, UA with microscopy (for proteinuria or Casts), complement tests (C3, C4 are often low in pts with active disease).
-**ANA is positive at high titer (1:160) in virtually all patients with SLE.
-Anti-dsDNA, Anti-Smith (Sm), Antiphospholipid if ANA is positive.
-Consider ECG to r/o pericarditis.
Treatment
Algorithm from the AAFP 2016.
Mild SLE (no major organ involvement)
-Hydroxychloroquine (Plaquenil) is indicated for its long-term protective effect on SLE-related organ damage. Preferred initial treatment for lupus arthritis. All lupus patients should be on hydroxychloroquine.
–Eye exams every 6 to 12 months to monitor for macular damage.
Moderate to severe SLE
Azathioprine and Cyclophosphamide are indicated for lupus nephritis or severe SLE.
–Azathioprine: CBC and CMP at least every 3 months to monitor for myelosuppression, hepatotoxicity, and lymphoproliferative disorders.
–Cyclophosphamide: CBC and CMP at least every 3 months to monitor for myelosuppression, malignancy, immunosuppression, and hemorrhagic cystitis.”
Mycophenolate is indicated for lupus nephritis or refractory SLE.
—CBC and CMP at least every 3 months to monitor for myelosuppression and infection.
Methotrexate is indicated for arthritis, cutaneous lupus, serositis, severe SLE.
—CBC and CMP at least every 3 months to monitor for myelosuppression, hepatic fibrosis, and pulmonary infiltrates and fibrosis.
Rituximab is indicated for severe refractory lupus. CBC every 2 to 4 months.
NSAIDs indicated for lupus joint pain. CBC and renal testing annually.
Glucocorticoids low dose vs. high dose based on the severity of the disease. Glucose levels every 3 to 6 months, and lipid panel and BMD annually.
-Refer to Rheumatology.
-Treatment of SLE:
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**Of the 11 ACR criteria for lupus, number 7, 9, 10, and 11 require laboratory evaluation. The rest can be obtained from history and physical examination.
-CBC evaluates for criteria # 9 which is hemolytic anemia with reticulocytosis OR Leukopenia <4000 on 2 or more occasions OR lymphopenia on 2 or more occasions OR low platelets (<100K) in the absence of offending drugs.
-UA with microscopy evaluates for criteria #7 which is proteinuria OR casts
-ANA evaluates for criteria #11. If ANA is positive, we will get labs to evaluate criteria #10, which is further testing.
**”Anti-Ro/SSA antibodies (with or without anti-La/SSB antibodies) identify pregnant women who are at increased risk of having a child with neonatal lupus syndrome. Anti-Ro/SSA antibodies may also be the only autoantibodies present in a subset of patients with “antinuclear antibody (ANA)-negative” SLE.” Uptodate.com
“Tan et al. in 1966 first identified a novel extractable anti-nuclear autoantibody (Ab) from a patient with systemic lupus erythematosus (SLE), Mrs. Stephanie Smith, and now the Ab is referred to as anti-Sm Ab” Lupus Open Access
Resources
The 11 ACR criteria for lupus.
http://www.aafp.org/afp/2016/0815/p284.html
http://www.rheumatology.org/Practice-Quality/Clinical-Support/Criteria/ACR-Endorsed-Criteria
http://www.uptodate.com/contents/the-anti-ro-ssa-and-anti-la-ssb-antigen-antibody-systems
Lemerle J, Renaudineau Y (2016) Anti-Sm and Anti-U1-RNP Antibodies: An Update. Lupus Open Access 1: e104.