ABIM Rheumatology key terms

A blood test that detects antibodies binding the cell nucleus. A positive result is common in healthy people, so it is used mainly as a screening test whose significance depends on the clinical picture and titer.

An antibody directed against double-stranded DNA that is relatively specific for systemic lupus erythematosus. Levels often track with disease activity, especially lupus nephritis.

An antibody against small nuclear ribonucleoproteins that is highly specific for systemic lupus erythematosus but less sensitive than anti-dsDNA. Its presence supports the diagnosis when the picture is otherwise unclear.

A chronic autoimmune disease in which autoantibodies and immune complexes injure multiple organs, including skin, joints, kidneys, blood cells, and the central nervous system. Diagnosis combines clinical features with serology.

Kidney involvement in systemic lupus erythematosus, typically from immune-complex glomerulonephritis. It causes proteinuria, hematuria, and declining kidney function and is classified by biopsy findings that guide treatment intensity.

An antimalarial drug used as a cornerstone therapy for systemic lupus erythematosus and other inflammatory diseases. It reduces flares and thrombotic risk; retinal toxicity requires periodic eye screening.

A disorder defined by persistent antiphospholipid antibodies together with thrombosis or pregnancy morbidity. It can occur alone or with lupus, and affected patients have a high risk of recurrent clots.

An antiphospholipid antibody that prolongs phospholipid-dependent clotting tests in the laboratory while paradoxically promoting thrombosis in patients. Its detection requires confirmatory testing because transient positivity is common.

An antibody, usually IgM, directed against the Fc portion of IgG. It is common in rheumatoid arthritis but also appears in other autoimmune diseases, infections, and healthy older adults, so it is not diagnostic alone.

An antibody against citrullinated proteins that is highly specific for rheumatoid arthritis and often present years before symptoms. It predicts more aggressive erosive disease and is useful in early diagnosis.

A chronic inflammatory arthritis, usually symmetric and involving small joints, driven by synovial inflammation that can erode bone and deform joints. Extra-articular disease may affect lungs, eyes, skin, and blood vessels.

A folate antagonist used as first-line disease-modifying therapy for rheumatoid arthritis and other inflammatory conditions. It is usually given weekly with folic acid supplementation; toxicity includes liver injury, marrow suppression, and lung disease.

A biologic drug that blocks the inflammatory cytokine TNF, used for rheumatoid arthritis, spondyloarthritis, and inflammatory bowel disease. Major risks include serious infection and reactivation of latent tuberculosis, which requires screening before use.

A chronic inflammatory disease of the axial skeleton causing back pain and stiffness that worsens with rest and improves with activity. Progressive inflammation can lead to spinal fusion and reduced mobility.

A human leukocyte antigen allele strongly associated with ankylosing spondylitis and related spondyloarthritides. It is common in the general population, so its presence supports but does not establish the diagnosis.

Inflammation of the sacroiliac joints, producing buttock or low back pain and often the earliest radiographic finding in axial spondyloarthritis. It may be detected by plain radiography or magnetic resonance imaging.

An inflammatory arthritis occurring with psoriasis, with patterns including asymmetric oligoarthritis, distal interphalangeal involvement, and axial disease. Nail changes and dactylitis are characteristic clues.

Diffuse swelling of an entire digit, sometimes called a sausage finger or toe, caused by inflammation of tendons, joints, and soft tissue. It is characteristic of psoriatic arthritis and other spondyloarthritides.

Inflammation at the site where a tendon, ligament, or joint capsule attaches to bone. Common in spondyloarthritis, it causes focal pain at sites such as the heel and can be seen on imaging.

An inflammatory arthritis caused by deposition of monosodium urate crystals in joints and tissues, producing sudden severe attacks often at the first metatarsophalangeal joint. Chronic disease can form tophi and erode bone.

Needle-shaped, negatively birefringent crystals found in joint fluid during gout. Their identification under polarized light microscopy confirms the diagnosis and helps distinguish gout from other crystal arthropathies.

Arthritis caused by deposition of calcium pyrophosphate crystals, typically affecting large joints such as the knee in older adults. Chondrocalcinosis on radiographs and rhomboid crystals in synovial fluid are characteristic.

A xanthine oxidase inhibitor that lowers serum urate and is used for long-term prevention of gout attacks. Treatment is started at low doses and titrated to a urate target, with monitoring for hypersensitivity reactions.

Infection of a joint space, usually bacterial, presenting with acute monoarticular pain, swelling, and fever. Prompt joint aspiration and antibiotics are essential because delay can destroy the joint.

Examination of fluid aspirated from a joint, including cell count, crystal examination, Gram stain, and culture. It distinguishes inflammatory, noninflammatory, and infectious arthritis and is central to evaluating acute monoarthritis.

A degenerative joint disease marked by cartilage loss, subchondral bone change, and osteophyte formation. It causes activity-related pain and stiffness and is managed with exercise, weight control, and analgesia rather than disease-modifying drugs.

A bony outgrowth at joint margins formed in response to altered joint loading and cartilage loss. It is a radiographic hallmark of osteoarthritis and may contribute to pain and restricted motion.

An inflammatory condition of older adults causing aching and morning stiffness of the shoulder and hip girdles with elevated inflammatory markers. It responds rapidly to low-dose glucocorticoids and often accompanies giant cell arteritis.

A large-vessel vasculitis affecting older adults, often involving the temporal and other cranial arteries. Headache, jaw claudication, and visual loss are feared features; high-dose glucocorticoids are started urgently to prevent blindness.

A nonspecific marker of inflammation that measures how quickly red cells settle in a tube. It rises in many inflammatory and infectious states and is useful for monitoring conditions such as polymyalgia rheumatica and giant cell arteritis.

An acute-phase protein produced by the liver whose blood level rises rapidly with inflammation or infection. It is used to assess disease activity and response to treatment, though it is not specific for any diagnosis.

Antibodies directed against proteins in neutrophil granules, detected as cytoplasmic or perinuclear patterns. They support the diagnosis of small-vessel vasculitides such as granulomatosis with polyangiitis and microscopic polyangiitis.

A small-vessel vasculitis causing necrotizing granulomatous inflammation of the respiratory tract and glomerulonephritis. Sinus and lung disease plus kidney involvement are typical; treatment combines glucocorticoids with immunosuppression.

A necrotizing small-vessel vasculitis that typically causes glomerulonephritis and pulmonary hemorrhage without granulomas. Most cases are associated with antineutrophil cytoplasmic antibodies, usually against myeloperoxidase.

An autoimmune disease causing fibrosis of skin and internal organs plus vasculopathy. Raynaud phenomenon and skin thickening are typical; internal organ involvement, especially lung and kidney disease, drives prognosis.

Episodic vasospasm of digits triggered by cold or stress, producing color changes and numbness. It may be primary or secondary to connective tissue diseases such as systemic sclerosis, where it often precedes other features.

Thickening and tightening of the skin of the fingers, leading to tapered digits and reduced hand mobility. It is a hallmark of systemic sclerosis and helps distinguish it from other connective tissue diseases.

An autoimmune disease in which lymphocytes infiltrate exocrine glands, causing dry eyes and dry mouth. It may occur alone or with other autoimmune diseases and carries an increased risk of lymphoma.

A group of autoimmune muscle diseases, including dermatomyositis and polymyositis, causing progressive proximal weakness and elevated muscle enzymes. Skin findings, malignancy screening, and lung involvement are important considerations.

An enzyme released from damaged skeletal muscle, measured in blood to detect and monitor muscle injury. Levels rise in inflammatory myopathies and other causes of rhabdomyolysis and fall with effective treatment.

A chronic pain disorder characterized by widespread musculoskeletal pain, fatigue, and disturbed sleep without joint inflammation or muscle damage. Diagnosis is clinical, and treatment emphasizes exercise, education, and selected medications.

A steroid hormone or drug that suppresses inflammation and immune responses, used widely in rheumatic disease. Long-term use causes osteoporosis, hyperglycemia, infection risk, and adrenal suppression, so doses are minimized when possible.

Reduced bone mass and disrupted bone architecture that increase fracture risk, often caused by glucocorticoids or menopause. It is diagnosed by bone densitometry and managed with calcium, vitamin D, exercise, and antiresorptive drugs.