6.1 Immunological Disorders

Why Immunological Disease Matters on Part II

General Diagnosis accounts for roughly 19% of NBCE Part II, and rheumatologic disease is a core clinical-impression sub-area. Patients with autoimmune and inflammatory conditions routinely seek chiropractic care for joint pain, stiffness, and back pain. Part II tests whether you can separate inflammatory from mechanical presentations, match each disease to its serologic and radiographic signature, and recognize when a musculoskeletal complaint is actually a systemic illness that changes your management — or demands immediate referral.

The high-yield framework is three questions: Is the pain symmetric or asymmetric? Does morning stiffness last less than 30 minutes (mechanical) or more than one hour (inflammatory)? Are there systemic signs — fever, weight loss, rash, cytopenias, serositis — that mechanical disorders do not produce?

Autoimmune Serology Basics

Four tests anchor most rheumatology vignettes:

• Antinuclear antibody (ANA): screening test for systemic lupus erythematosus (SLE); positive in roughly 95% of lupus patients but nonspecific (also seen in Sjogren syndrome, scleroderma, and low-titer healthy individuals)
• Rheumatoid factor (RF): IgM against the Fc portion of IgG; positive in about 70–80% of rheumatoid arthritis (RA) patients but nonspecific (chronic infection, hepatitis C, healthy elderly)
• Anti-cyclic citrullinated peptide (anti-CCP): similar sensitivity to RF for RA but far more specific — the best single blood test for confirming RA
• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP): nonspecific inflammation markers; a very high ESR (greater than 50–100 mm/hr) suggests polymyalgia rheumatica or giant cell arteritis, infection, or malignancy rather than simple mechanical pain

Systemic Lupus Erythematosus

SLE is a multisystem autoimmune disease classically affecting young women of childbearing age, with higher prevalence in African American, Hispanic, and Asian populations. Key features include a malar (butterfly) rash across the cheeks and nose sparing the nasolabial folds, photosensitivity, non-erosive symmetric small-joint arthritis, serositis (pleuritis, pericarditis), renal disease (lupus nephritis — the major cause of morbidity), central nervous system involvement (seizures, psychosis), cytopenias, and oral ulcers.

ANA is sensitive; anti-double-stranded DNA (anti-dsDNA) and anti-Smith (anti-Sm) antibodies are highly specific. Anti-dsDNA titers correlate with renal flare activity, and complement (C3, C4) falls during active disease. Drug-induced lupus (procainamide, hydralazine, isoniazid) is associated with anti-histone antibodies. A patient with new rash, arthritis, and cytopenias is a referral case — not a routine adjusting opportunity.

Rheumatoid Arthritis versus Osteoarthritis

This contrast is one of the most reliable on the boards:

RA is driven by synovial inflammation forming pannus, which erodes cartilage and bone. Classic late deformities include ulnar deviation, swan-neck and boutonniere deformities. A critical chiropractic-relevant complication is atlantoaxial (C1–C2) instability from transverse ligament erosion — patients with long-standing RA should be screened with flexion radiographs when indicated before any cervical manipulation, and upper cervical adjusting is approached with caution or avoided.

Seronegative Spondyloarthropathies

These are RF-negative, often HLA-B27-associated, and share enthesitis and sacroiliac involvement:

• Ankylosing spondylitis (AS): young men (teens to 30s) with insidious low back pain and morning stiffness that improves with activity and worsens with rest — the opposite of mechanical back pain. Bilateral symmetric sacroiliitis is the earliest radiographic finding; late disease produces syndesmophytes and the bamboo spine. Physical findings include decreased lumbar flexion (positive Schober test: less than 5 cm excursion between two points marked 10 cm apart) and reduced chest expansion. Extraskeletal features include acute anterior uveitis, aortitis, and apical lung fibrosis. HLA-B27 is positive in about 90% of white patients with AS
• Psoriatic arthritis: classically involves DIP joints with psoriatic skin and nail changes (pitting, onycholysis); sausage digits (dactylitis) and the pencil-in-cup radiographic deformity are classic
• Reactive arthritis: follows genitourinary (Chlamydia) or GI (Shigella, Salmonella, Campylobacter) infection by one to four weeks. The classic triad is urethritis, conjunctivitis, and arthritis — usually an asymmetric oligoarthritis of the lower extremities

Crystal Arthropathies: Gout versus Pseudogout

Definitive diagnosis of any acute hot joint is by arthrocentesis — never assume crystals without excluding septic arthritis, a joint-destroying emergency requiring drainage and IV antibiotics. Refer; do not adjust through an infected joint.

Other High-Yield Conditions

• Sjogren syndrome: autoimmune destruction of lacrimal and salivary glands causing dry eyes and dry mouth (sicca); associated with anti-Ro/SSA and anti-La/SSB; may accompany RA or SLE
• Polymyalgia rheumatica (PMR): aching and stiffness of shoulder and hip girdles in patients over 50, ESR typically greater than 50 mm/hr, dramatic response to low-dose prednisone
• Giant cell (temporal) arteritis: PMR plus headache, scalp tenderness, jaw claudication, and risk of irreversible blindness from anterior ischemic optic neuropathy — start high-dose corticosteroids immediately and refer; biopsy confirms but should not delay treatment
• Fibromyalgia: widespread pain lasting more than three months with fatigue, nonrestorative sleep, and cognitive symptoms; diagnosis of exclusion after ruling out hypothyroidism and inflammatory arthritis; labs and imaging are normal. Chiropractic supportive care may help, but the exam tests recognition that it is not an inflammatory arthropathy
• Lyme disease: Borrelia burgdorferi transmitted by the Ixodes (deer) tick. Stage 1 shows erythema migrans — an expanding annular bull's-eye rash; later stages cause migratory oligoarthritis (classically the knee), facial nerve palsy, and carditis. First-line treatment is doxycycline

Chiropractic Relevance and Red Flags

Treat with caution or refer when you see: fever with a hot swollen joint (septic arthritis); new neurologic deficits with lupus or vasculitis; jaw claudication or sudden vision change (giant cell arteritis); inflammatory back pain under age 40 with night pain and sacroiliac tenderness (AS); long-standing RA before cervical manipulation (atlantoaxial instability); expanding rash with systemic symptoms (Lyme, SLE flare).

Takeaways: inflammatory pain is symmetric, prolonged-morning-stiffness, and systemic; RA spares DIP joints while psoriatic arthritis targets them; AS back pain improves with activity; any hot monoarticular joint needs arthrocentesis before crystals; and positive ANA alone does not diagnose lupus.