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Rheumatology

The study and treatment of rheumatic diseases affecting joints, muscles, and connective tissue.

βœ“ Introduction to Rheumatology

βœ“ Introduction to Rheumatology is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Rheumatoid Arthritis Basics

βœ“ Rheumatoid Arthritis Basics is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Osteoarthritis Basics

βœ“ Osteoarthritis Basics is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Gout Basics

βœ“ Gout Basics is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Lupus Basics

βœ“ Lupus Basics is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Ankylosing Spondylitis Basics

βœ“ Ankylosing Spondylitis Basics is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Vasculitis Basics

βœ“ Vasculitis Basics is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Scleroderma Basics

βœ“ Scleroderma Basics is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ SjΓΆgren's Basics

βœ“ SjΓΆgren's Basics is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Myositis Basics

βœ“ Myositis Basics is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Osteoporosis Basics

βœ“ Osteoporosis Basics is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Rheumatology Ethics Basics

βœ“ Rheumatology Ethics Basics is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Rheumatology Careers

βœ“ Rheumatology Careers is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Advanced Rheumatology

βœ“ Advanced Rheumatology is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Rheumatoid Arthritis

βœ“ Rheumatoid Arthritis is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Osteoarthritis

βœ“ Osteoarthritis is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Gout

βœ“ Gout is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Lupus

βœ“ Lupus is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Ankylosing Spondylitis

βœ“ Ankylosing Spondylitis is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Vasculitis

βœ“ Vasculitis is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Scleroderma

βœ“ Scleroderma is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ SjΓΆgren's

βœ“ SjΓΆgren's is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Myositis

βœ“ Myositis is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Osteoporosis

βœ“ Osteoporosis is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Rheumatology Ethics

βœ“ Rheumatology Ethics is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Core principles, practical applications, and advanced concepts that build deep understanding.

βœ“ Rheumatology Research

βœ“ Rheumatology Research is a clinical topic covering pathophysiology, diagnosis, evidence-based treatment, and patient care.

Key points: Time complexity (Big-O), space complexity, correctness proof, and practical implementation trade-offs.

Key Clinical Formulas & Scores

DAS28 (Disease Activity Score β€” 28 joints):
DAS28 = 0.56 Γ— √(TJC28) + 0.28 Γ— √(SJC28) + 0.70 Γ— ln(ESR) + 0.014 Γ— GH
TJC28 = tender joint count (0-28)
SJC28 = swollen joint count (0-28)
ESR = erythrocyte sedimentation rate
GH = global health assessment (VAS 0-100 mm)
Remission: <2.6 | Low: 2.6-3.2 | Moderate: 3.2-5.1 | High: >5.1
ACR/EULAR 2010 Rheumatoid Arthritis Classification:
Joint involvement: 1 large=0, 2-10 large=1, 1-3 small=2, 4-10 small=3, >10 joints=5
Serology: RF- AND CCP-=0, RF+ OR CCP+ (low)=2, RF+ OR CCP+ (high)=3
Acute phase reactants: Normal CRP/ESR=0, Elevated CRP or ESR=1
Symptom duration: <6 weeks=0, β‰₯6 weeks=1
Score β‰₯6/10 = definite RA
ACR/EULAR 2019 SLE Classification:
Entry criterion: ANA β‰₯1:80 (HEp-2) β€” required
Clinical domains (weighted):
β€’ Constitutional: Fever (2)
β€’ Hematologic: Leukopenia (3), Thrombocytopenia (4), Autoimmune hemolysis (4)
β€’ Neuropsychiatric: Delirium (2), Psychosis (3), Seizure (5)
β€’ Mucocutaneous: Non-scarring alopecia (2), Oral ulcers (2), Acute cutaneous lupus (6)
β€’ Serosal: Pleural/pericardial effusion (5), Acute pericarditis (6)
β€’ Musculoskeletal: Joint involvement (6)
β€’ Renal: Proteinuria >0.5 g/24h (4), Class III/V lupus nephritis (8), Class II/IV lupus nephritis (10)
Immunologic domains (weighted):
β€’ ANA (entry)
β€’ Anti-dsDNA (6), Anti-Smith (6), Antiphospholipid antibodies (2)
β€’ Complement C3 or C4 low (3/4)
Score β‰₯10 = classification as SLE
SLICC Criteria for SLE:
β‰₯4 of 17 criteria (at least 1 clinical + 1 immunologic)
Clinical: Acute cutaneous lupus, Chronic cutaneous lupus, Oral/nasal ulcers, Non-scarring alopecia, Synovitis β‰₯2 joints, Serositis, Neurologic (seizures, psychosis), Hemolytic anemia, Leukopenia (<4,000), Thrombocytopenia (<100,000)
Immunologic: ANA, Anti-dsDNA, Anti-Sm, Antiphospholipid antibodies, Low complement (C3, C4, CH50), Direct Coombs (without hemolytic anemia)
BASDAI (Ankylosing Spondylitis Activity):
6 questions, VAS 0-10 each:
1. Fatigue 2. Spinal pain 3. Peripheral joint pain 4. Enthesitis
5. Morning stiffness duration 6. Morning stiffness severity
BASDAI = 0.2 Γ— (Q1 + Q2 + Q3 + Q4 + 0.5 Γ— Q5 + 0.5 Γ— Q6)
Score: <4 = inactive, β‰₯4 = active disease
BASFI (functional index): 10 questions, mean score 0-10

Core Concepts

Rheumatoid Arthritis

Symmetric inflammatory polyarthritis, small joints (MCP, PIP, MTP), morning stiffness >1 hour. Serology: RF (70%), anti-CCP (60-70%, more specific). Radiographic: periarticular osteopenia, joint space narrowing, erosions. Extra-articular: rheumatoid nodules, interstitial lung disease, vasculitis, Felty syndrome. Treatment: methotrexate (first-line DMARD, 15-25 mg/week), hydroxychloroquine, sulfasalazine, leflunomide. Biologics: TNF-Ξ± inhibitors (adalimumab, etanercept, infliximab), IL-6 inhibitors (tocilizumab), JAK inhibitors (tofacitinib, baricitinib), rituximab (anti-CD20). Treat-to-target (DAS28 <2.6 or remission).

Gout

Monosodium urate crystal deposition. Acute monoarthritis (podagra = first MTP, most common). Risk factors: hyperuricemia (purine-rich diet, alcohol, diuretics, CKD, obesity). Diagnosis: joint aspiration β€” needle-shaped negatively birefringent crystals. Acute treatment: NSAIDs (indomethacin), colchicine, corticosteroids. Chronic: urate-lowering therapy if β‰₯2 flares/year, tophi, or urate nephropathy. Allopurinol (first-line, start 100 mg daily, titrate to target sUA <6 mg/dL), febuxostat, probenecid. Prophylaxis with colchicine 0.6 mg BID Γ— 3-6 months when starting ULT.

Lupus Nephritis

Class I: mesangial (mildest). Class II: mesangial proliferative. Class III: focal (<50% glomeruli). Class IV: diffuse (β‰₯50%) β€” most severe. Class V: membranous. Class VI: sclerosing. Class III/IV: high-dose glucocorticoids + mycophenolate mofetil (MMF) or cyclophosphamide (NIH protocol). Class V: MMF or CNIs. Maintenance: MMF or azathioprine for at least 3 years. Biologics: belimumab (anti-BLyS), voclosporin. Monitoring: urinalysis, proteinuria, complement levels, anti-dsDNA.

Clinical Case Studies

Case 1: New Onset Rheumatoid Arthritis

Patient: 45-year-old female, symmetric joint pain and swelling in hands and feet Γ— 8 weeks, morning stiffness lasting 2 hours. Exam: swollen MCP2-5 and MTP2-5 bilaterally, warmth, limited ROM. Labs: RF 85, anti-CCP 120, ESR 65, CRP 4.2. X-ray: periarticular osteopenia in MCP joints.

Diagnosis: Rheumatoid Arthritis (ACR/EULAR score = 8/10: 4-10 small joints=3, serology high positive=3, elevated CRP=1, duration β‰₯6 weeks=1).

Management: Start methotrexate 15 mg/week with folic acid 1 mg daily (except MTX day). Prednisone 10 mg daily as bridge therapy (taper over 3 months). Hydroxychloroquine 400 mg daily added. Tuberculosis screening before biologics. Follow-up DAS28 in 3 months. Target: DAS28 <2.6 or clinical remission. If inadequate response at 6 months: add TNF-Ξ± inhibitor (adalimumab 40 mg SC every 2 weeks).

Case 2: Acute Gout Flare

Patient: 52-year-old male, excruciating pain in right first MTP Γ— 2 days, red, hot, swollen, unable to bear weight. PMH: HTN, BMI 35, drinks beer daily. Tophus on right ear helix. Serum uric acid 9.2 mg/dL. Joint aspiration: needle-shaped negatively birefringent crystals in polarized light.

Diagnosis: Acute gouty arthritis (podagra).

Management: Acute: indomethacin 50 mg TID Γ— 5 days (or colchicine 1.2 mg then 0.6 mg 1 hour later). Ice packs. Once flare resolves: initiate allopurinol 100 mg daily, titrate every 2-5 weeks to target sUA <6 mg/dL. Colchicine 0.6 mg BID prophylaxis for 3-6 months when starting ULT. Lifestyle: reduce alcohol, purine-rich foods, weight loss. Avoid starting ULT during acute flare if patient already on ULT (continue current dose).

Case 3: Lupus Nephritis (Class IV)

Patient: 28-year-old female, malar rash, photosensitivity, joint pain Γ— 3 months. New onset facial edema, foamy urine. Labs: ANA 1:640 (homogeneous), anti-dsDNA 350, C3 35 (low), C4 <10 (low), proteinuria 3.8 g/24h, hematuria with cellular casts. Renal biopsy: Class IV-G (A/C) diffuse proliferative glomerulonephritis with crescents.

Diagnosis: Systemic Lupus Erythematosus with Class IV lupus nephritis (ACR/EULAR score >10).

Management: Induction: IV methylprednisolone 1 g daily Γ— 3 days, then prednisone 1 mg/kg/day. Mycophenolate mofetil 1 g BID (or cyclophosphamide IV monthly Γ— 6 months if crescents/severe). ACE inhibitor for proteinuria. Hydroxychloroquine 400 mg daily for all SLE patients. Maintenance: MMF 1-1.5 g BID or azathioprine 2 mg/kg daily for β‰₯3 years. Nephrology follow-up, renal function monitoring.

Practice Questions

Q1: A patient with RA has TJC28=8, SJC28=6, ESR=45, and GH=60. What is the DAS28?
A: DAS28 = 0.56 Γ— √8 + 0.28 Γ— √6 + 0.70 Γ— ln(45) + 0.014 Γ— 60 = 0.56Γ—2.83 + 0.28Γ—2.45 + 0.70Γ—3.81 + 0.84 = 1.58 + 0.69 + 2.67 + 0.84 = 5.78. High disease activity (>5.1).
Q2: What is the most specific serologic marker for rheumatoid arthritis?
A: Anti-cyclic citrullinated peptide (anti-CCP) antibodies β€” specificity >95% (compared to RF ~85%). High titers predict erosive disease.
Q3: A patient has ANA 1:320, malar rash, arthritis, leukopenia, anti-dsDNA positive, and low C3/C4. How many ACR/EULAR 2019 criteria points?
A: ANA entry (0), Acute cutaneous (6) + Joint (6) + Leukopenia (3) + Anti-dsDNA (6) + Low complement (4) = 25 points. Score β‰₯10 = classification as SLE.
Q4: What is the first-line urate-lowering therapy for gout?
A: Allopurinol (xanthine oxidase inhibitor) β€” start 100 mg daily, titrate every 2-5 weeks to target serum uric acid <6 mg/dL. Febuxostat is alternative if allopurinol contraindicated.
Q5: What is the treatment of choice for induction therapy in Class IV lupus nephritis?
A: High-dose glucocorticoids + mycophenolate mofetil (MMF) 1-1.5 g BID, or IV cyclophosphamide (NIH protocol: 0.5-1 g/mΒ² monthly Γ— 6 months). MMF has comparable efficacy to cyclophosphamide with better safety profile.

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