1. Diagnosis of RA:
- Cardinal - marginal erosions/joint space narrowing. Seen within 2-3 months of onset, often  present by 6 months.

(source)

- CBC may show mild leukocytosis, thrmobocytosis, mild anemia (i.e. chronic disease type) 

- ESR or CRP may be elevated 

- RF is positive in 75% of people with RA, can be as low as 50% early in the disease. Can also be elevated in chronic active Hep C and with Parvo B19

- RA is more common in the first 3 months postpartum 

- Severe long standing RA may lead to interstitial pneumonitis (esp in men), often appears 5+ years after diagnosis. 

2. Steroids interfere with TSH release and can decrease secretion of thyroid binding globulin. 

3. Treatment of RA

- Start DMARDs as soon as possible (early DMARD has better outcomes than starting with NSAID +/- steroids and then initiating DMARDs later) 

- Mildly active RA: start either hydroxychloroquine or sulfasalazine 

- Moderate to severely active RA: start methotrexate plus either NSAID or steroid. 

- Can add TNF-a inhibitor if DMARD is not enough, however there is not currently evidence that a TNF-a inhibitor alone is an effective management strategy for RA. 

- Methotrexate is contraindicated in people who regularly drink as it alcohol increases the risk of mtx-induced hepatotoxicity 

4. HIV associated psoriatic arthritis: 

- CD4<200 can predispose to psoriasis and other skin conditions-- photodermatitis, prurigo nodularis, mollsucum, drug reactions

- 20-40% of those with psoriasis will develop arthritis 

- Suspect in someone with explosive onset, widespread psoriasis with dactylitis, significant DIP joint involvement, asymmetric joint involvement, enthesitis, joint ankylosis. 

5. Whipple disease:

- Trophyeryma whippelii 

- Arthritis, diarrhea, malabsorption, CNS and constitutional symptoms (i.e. skin findings)

- Arthritis is migratory and chronic 

6. Uveitis

- Anterior: seronegative spondyloarthropathies (esp unilateral presentation that fluctuates between the 2 eyes over time), lupus, sarcoid, vasculidities, whipple disease

- Posterior: sarcoid, vasculidites 

7. Diagnose ankylosing spondylitis with MRI (need radiographic evidence of sacroilitis to make the diagnosis) 

8. Scleroderma

- Anti topoisomerase I aka anti scl-70 is seen in ~50% of people with diffuse systemic sclerosis and predicts development of ILD. Diffuse systemic sclerosis tends to have skin thickening proximal to the elbows and knees. Can affect face. 

- Anti centromere antibody is associated with limited cutaneous systemic sclerosis aka CREST syndrome (calcinosis, raynaud's, esophageal dysmotility, scelerodactyly, teleangiectasias), skin thickening distal to the elbows and knees, can affect face. 

9. Infliximab

- Often causes development of antibodies: ANA, anti-sm, anti-dsDNA

- Rarely causes drug-induced lupus. If it does, stop it and start prednisone. Consider adding hydroxychloroquine as well 

- Drug induced lupus has mostly cutaenous and pleuropericardial involvement-- rarely CNS or renal. 

10. Lupus 

- ACE inhibitors are first-line for control of hypertension in lupus nephritis patients as it helps reduce proteinuria. 

- Rash triggered by UV-A and UV-B (so rash that appears after outdoors trip etc), erythematous plaques with fine scale that spares the nasolabial folds (vs rosacea, which involves nasolabial folds and has more of a pustular acneiform appearance and doesn't have any systemic symptoms) 

- Usually have anemia, leukopenia or lymphopenia 

- Can cause elevated ANA in first degree family members (!)