CONFIRMING DIAGNOSIS Identifying the causative organism in a Gram stain or culture of synovial fluid or a biopsy of synovial membrane confirms septic arthritis. When synovial fluid culture is negative, positive blood culture may confirm the diagnosis.
Joint fluid analysis shows gross pus or watery, cloudy fluid of decreased viscosity, usually with 50,000/µl or more white cells, primarily neutrophils. Synovial fluid glucose is usually more than 40 mg/dl. (See Other types of arthritis, page 584.)
Other diagnostic measures include the following:
❑ X-rays can show typical changes as early as 1 week after initial infection — distention of joint capsules, for example, followed by narrowing of joint space (indicating cartilage damage) and erosions of bone (joint destruction).
❑ White blood cell count may be elevated, with many polymorphonuclear cells; erythrocyte sedimentation rate is increased.
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Source: Professional Guide to Diseases (Eighth Edition), 2005
Juvenile rheumatoid arthritis:
Diagnosis
(Professional Guide to Diseases (Eighth Edition))
Persistent joint pain and the rash and fever clearly point to JRA. Laboratory tests are useful for ruling out other inflammatory or even malignant diseases that can mimic JRA. Disease activity and response to therapy can also be monitored through laboratory results.
❑ Complete blood count shows decreased hemoglobin levels, neutrophilia, and thrombocytosis.
❑ Erythrocyte sedimentation rate and C-reactive protein, haptoglobin, immunoglobulin, and C3 complement levels may be elevated.
❑ ANA test may be positive in patients who have pauciarticular JRA with chronic iridocyclitis.
❑ RF is present in 15% of JRA cases, compared with 85% of rheumatoid arthritis cases.
❑ Positive HLA-B27 antigens may forecast later development of ankylosing spondylitis.
❑ X-rays in early stages reveal changes, including soft-tissue swelling, effusion, and periostitis in affected joints. Later, osteoporosis and accelerated bone growth may appear, followed by subchondral erosions, joint space narrowing, bone destruction, and fusion.
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Source: Professional Guide to Diseases (Eighth Edition), 2005
Rheumatoid arthritis:
Diagnosis
(Professional Guide to Diseases (Eighth Edition))
Typical clinical features suggest this disorder, but a definitive diagnosis is based on laboratory and other test results:
❑ X-rays — in early stages, show bone demineralization and soft-tissue swelling; later, loss of cartilage and narrowing of joint spaces; finally, cartilage and bone destruction and erosion, subluxations, and deformities
❑ rheumatoid factor test — positive in 75% to 80% of patients as indicated by a titer of 1:160 or higher
❑ synovial fluid analysis — reveals increased volume and turbidity but decreased viscosity and complement (C3 and C4) levels; white blood cell count usually exceeds 10,000/µl
❑ erythrocyte sedimentation rate — elevated in 85% to 90% of patients (may be useful to monitor response to therapy because elevation commonly parallels disease activity)
❑ complete blood count — usually reveals moderate anemia and slight leukocytosis.
A C-reactive protein test can help monitor response to therapy.
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Source: Professional Guide to Diseases (Eighth Edition), 2005
Acute Monoarticular Arthritis:
Differential Overview
(Field Guide to Bedside Diagnosis)
❑ Injury
❑ Gout
❑ Osteoarthritis
❑ Lyme disease
❑ Gonococcal arthritis
❑ Seronegative spondyloarthropathy
❑ Septic arthritis
❑ Pseudogout
❑ Septic bursitis
❑ Avascular necrosis
Diagnostic Approach
Ascertain that arthritis (joint inflammation) is present by eliciting pain on joint motion. A hot, swollen joint with constitutional symptoms such as fever, weight loss, and malaise suggests infection. The skin may hold clues to psoriasis, systemic lupus, viral exanthems, Lyme disease, and others. Erythema nodosum occurs with sarcoidosis or inflammatory bowel disease. Urethritis suggests gonorrhea or Reiter syndrome. A monoarticular presentation of a polyarticular disease may be rarely seen in rheumatoid arthritis, Reiter syndrome, ankylosing spondylitis, psoriatic arthritis, inflammatory bowel disease, and sarcoidosis.
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Source: Field Guide to Bedside Diagnosis, 2007
Arthritis/Dermatitis:
Differential Overview
(Field Guide to Bedside Diagnosis)
❑Lyme disease
❑Erythema nodosum
❑Rheumatoid arthritis
❑Systemic lupus erythematosus
❑Psoriatic arthritis
❑Disseminated gonococcemia
❑Sarcoidosis
❑Scleroderma
❑Dermatomyositis
❑Reiter syndrome
❑Rheumatic fever
❑Behçet syndrome
❑Still disease
❑Hypersensitivity vasculitis
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Source: Field Guide to Bedside Diagnosis, 2007
Polyarticular Arthritis:
Differential Overview
(Field Guide to Bedside Diagnosis)
❑ Osteoarthritis
❑ Rheumatoid arthritis
❑ Lyme arthritis
❑ Systemic lupus erythematosus
❑ Psoriatic arthritis
❑ Polyarticular gout
❑ Viral arthritis
❑ Scleroderma
❑ Reiter syndrome
❑ Inflammatory bowel disease
❑ Gonococcal arthritis
❑ Ankylosing spondylitis
❑ Systemic vasculitis
❑ Sarcoidosis
❑ Pseudogout (CPPD)
❑ Acute rheumatic fever
❑ Still disease
Diagnostic Approach
Ascertain that the pain is articular; that is, it is exacerbated by the function of the joint. Detecting synovitis limits the differential to inflammatory arthridites and systemic rheumatic diseases. Findings of synovitis include palpable soft tissue bogginess around a joint, warmth over a joint, or effusion. Involvement of the wrists, elbows, or metacarpophalangeal joints implies inflammatory disease rather than osteoarthritis. Morning stiffness persisting for as long as 1 to 2 hours, relieved by NSAIDs, is typical for inflammatory arthritis, as is a history of a red joint.
Differentiating features include the following: Erythema nodosum: sarcoidosis, inflammatory bowel disease-related arthritis, or Behçet disease. Rash: lupus, Still disease, vasculitis, dermatomyositis, endocarditis, disseminated gonorrhea, or Behçet disease. Fever greater than 40˚C: Still disease, bacterial arthritis, or lupus. Fever preceding arthritis: viral arthritis, Lyme, reactive arthritis, Still
desease, or bacterial endocarditis. Spiking fever: bacterial infection or Still
disease. Splenomegaly: rheumatoid arthritis and lupus. Raynaud: scleroderma, mixed connective tissue disease, or lupus. Oral ulcers: lupus, Behçet disease, or viral arthritis. Dry eyes and mouth: Sjögren syndrome, mixed connective tissue
disease, or lupus. Ocular findings: lupus, Behçet disease, sarcoidosis, or reactive arthritis. Migratory arthritis: gonococcemia, rheumatic fever, meningococcemia, viral arthritis, lupus, acute leukemia, or Whipple disease. Episodic recurrences: Lyme, crystal-induced arthritis, inflammatory bowel disease, Still disease, or lupus. Morning stiffness: rheumatoid arthritis, polymyalgia rheumatica, Still
disease, or viral arthritis. Symmetric small-joint synovitis: rheumatoid arthritis, lupus, or viral arthritis.
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Source: Field Guide to Bedside Diagnosis, 2007
Psoriatic arthritis:
Diagnosis
(Handbook of Diseases)
Inflammatory arthritis in a patient with psoriatic skin lesions suggests psoriatic arthritis. X-rays confirm joint involvement and show:
❑ marginal erosion at interphalangeal joints with areas of thin, “fluffy” new bone formation
❑ “whittling” of the distal end of the terminal phalanges
❑ “pencil-in-cup” deformity of the distal interphalangeal joints
❑ relative absence of osteoporosis
❑ sacroiliitis
❑ atypical spondylitis with syndesmophyte formation, resulting in hyperostosis and paravertebral ossification, which may lead to vertebral fusion.
Blood studies indicate negative rheumatoid factor and elevated erythrocyte sedimentation rate and uric acid levels.
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Source: Handbook of Diseases, 2003
Juvenile rheumatoid arthritis:
Diagnosis
(Handbook of Diseases)
Persistent joint pain, rash, and fever clearly point to JRA. Laboratory tests are useful for ruling out other inflammatory or even malignant diseases that can mimic JRA and for monitoring disease activity and response to therapy.
❑ Complete blood count shows decreased hemoglobin levels, neutrophilia, and thrombocytosis.
❑ Erythrocyte sedimentation rate, complement (C)-reactive protein, haptoglobin, immunoglobulin, and C3 levels may be elevated.
❑ Test results may be positive for ANAs in patients who have pauciarticular JRA with chronic iridocyclitis.
❑ RF is present in 15% of patients with JRA, as compared with 85% of patients with RA.
❑ Positive HLA-B27 test may forecast later development of ankylosing spondylitis.
❑ Early X-ray changes include soft-tissue swelling, effusion, and periostitis in affected joints. Later, osteoporosis and accelerated bone growth may appear, followed by subchondral erosions, joint space narrowing, bone destruction, and fusion.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
Rheumatoid arthritis:
Diagnosis
(Handbook of Diseases)
Typical signs and symptoms suggest RA, with a firm diagnosis supported by laboratory and other test results:
❑ X-raysin early stages show bone demineralization and soft-tissue swelling; later, loss of cartilage and narrowing of joint spaces; and finally, cartilage and bone destruction and erosion, subluxations, and deformities.
❑ RF is positive in 75% to 80% of patients, as indicated by a titer of 1:160 or higher.
❑ Synovial fluid analysisshows increased volume and turbidity but decreased viscosity and elevated white blood cell counts (often greater than 10,000/µl).
❑ Serum protein electrophoresis may show elevated serum globulin levels.
❑ Erythrocyte sedimentation rate and C-reactive protein are elevated in 85% to 90% of patients (may be useful to monitor response to therapy because elevation typically parallels disease activity).
❑ Complete blood count usually shows moderate anemia, slight leukocytosis, and thrombocytosis.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
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