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Flashcards in Diagnostics Deck (61)
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1
Q

How to diagnose a rheumatological disease?

A

H&P

Labs/radiographic findings- confirmatory

2
Q

Define Sensitivity

A

Proportion of patients with positive test who have the disease

3
Q

Define Specificity

A

Proportion of patients with negative test who do not have the disease

4
Q

H&P in Rheumatologic Diseases

A

Increase “pretest probability” with history

Look for clues on physical exam

5
Q

When to Order Serologic Tests

A

Assist in confirming a specific diagnosis
Formulate appropriate management
Evaluate/monitor disease activity

6
Q

Define Acute Phase Reactants

A

Proteins synthesized by the liver and induced by inflammation and tissue injury/necrosis

7
Q

Define Erythrocyte Sedimentation Rate (ESR)

A

Distance at which erythrocytes have settled in a vertical column of anticoagulated blood in an hour (mm/hr)

8
Q

ESR Measurement

A

Indirect measurement of serum acute phase reactant concentrations

9
Q

ESR Influenced by

A

Size
Shape
Number of RBCs

10
Q

ESR Increased by

A
Acute phase reactants
Paraproteins
Anemia (fewer, less repellent forces)
Age
Gender
Pregnancy
DM
Renal failure
Malignancy
Tissue damage
11
Q

ESR in Polymyalgia Rheumatica

A

ESR >40 mm/hr

12
Q

ESR in Giant Cell Arteritis

A

ESR >90 mm/hr

13
Q

Define C-Reactive Protein (CRP)

A

Acute phase protein produced by the liver

14
Q

What is CRP produced in response to and enhance?

A

Produced in response to inflammation

Enhances complement binding & phagocytosis

15
Q

What does CRP measure?

A

Direct measure of acute phase reactants

16
Q

Pros & Cons of CRP

A

Pro: responds more quickly
Cons: more expensive, don’t always know how to interpret

17
Q

Define Rheumatoid Factor

A

Auto antibody directed against Fc portion of IgG

18
Q

Conditions Causing Positive Rheumatoid Factor

A
SLE
Scleroderma
Sjogren syndrome
Cryoglobulinemia
Infections: hepatitis, TB, SBE, syphillis, parasitic disease, viral
Pulmonary diseases
Malignancy
19
Q

Define Post Test Probability

A

Probability that the patient has the disease given a positive test result

20
Q

How is rheumatoid factor measured?

A

Less than 1:80 is negative

21
Q

Anti-CCP (citrulline antibody)

A

Antibody directed against “citrullinated” peptide residues present within inflammatory sites

22
Q

Anti-CCP vs. RF

A

Sensitivity equal

Specificity: anti-CCP > RF

23
Q

Anti-Nuclear Antibodies (ANA)

A

Autoantibodies directed at nuclear antigens or content of the cell nucleus

24
Q

What is a serologic hallmark of systemic autoimmune disease?

A

ANAs

25
Q

Uses of ANA

A

Help establish diagnosis when suggestive of an autoimmune or connective tissue disorder
Exclude such disorders with uncertain clinical findings
Subclassify a patient with an established diagnosis of an autoimmune or connective tissue disease
Monitor disease activity

26
Q

When is a positive ANA seen?

A

Systemic autoimmune disease
Organ-specific immune diseases
Variety of infections
Normal individuals

27
Q

Non-Rheumatic Conditions Causing Positive ANA

A
Normal individuals
Hepatic diseases
Pulmonary diseases
Chronic infections
Malignancies
Hematologic disorders
Drug-induced
Misc: autoimmune thyroiditis, DM1
28
Q

Criteria for Classification of SLE (Need 4+)

A
Malar rash
Discoid rash
Photosensitivity
Oral ulcers
Arthritis
Serositis
Neurologic disorder
Renal disorder: proteinuria or casts
Hematologic disorder: leukopenia, lymphocytopenia, or thrombocytopenia
Immunologic disorders: antiphopholipid antibody, abnormal titer of anti-nDNA, anti-Sm, confirmed false + STS
Positive antinuclear antibody
29
Q

When to Order an ANA

A

Moderate pre-test probability: 3/11 lupus criteria

30
Q

ANA Specific Autoantibody Tests

A
Anti-dsDNA
Anti-Sm
Anti-centromere antibody (ACA)
Anti-topoisomerase I (Scl-70)
Anti-Ro (SS-A) and Anti-La (SS-B)
Anti-U1 snRNP
Anti-Jo-1 (anti-histidyl-tRNA synthestase)
31
Q

Anti-dsDNA

A

Specific for SLE

May fluctuate with disease activity

32
Q

Anti-Sm (Smith antigen)

A

Highly specific for SLE

33
Q

Anti-Centromere Antibody (ACA)

A

Associated with CREST & scleroderma

34
Q

Anti-Topoisomerase I (Scl-70)

A

Associated with diffuse scleroderma

35
Q

Anti-RO (SS-A) & Anti- La (SS-B)

A

Associated with Sjogren’s
Can be seen in SLE
Maybe associated with neonatal heart block in babies of mothers with antibody

36
Q

Anti-U1 snRNP

A

Part of criteria for Mixed Connective Tissue Disease (MCTD)

May be seen in other rheumatic diseases

37
Q

Anti-Jo-1 (anti-histidyl-tRNA synthestase)

A

Specific for myositis associated with interstitial lung disease
Raynaud’s

38
Q

Use of Serum Complements

A

Monitoring disease activity in SLE

39
Q

Low C3, C4 Levels

A

Reflect consumption of complement

Active SLE

40
Q

Antineutrophil Cytoplasmic Antibodies

A

Group of autoantibodies mainly of the IgG type directed against antigens in the cytoplasm of neutrophil granulocytes & monocytes
P-ANCA: perinuclear
C-ANCA: cytoplasmic

41
Q

ANCA Association

A

Vasculitis

42
Q

Most Common Rheumatologic Disorder with a Positive C-ANCA

A

Wegener’s granulomatosis

Microscopic polyangiitis

43
Q

Most Common Rheumatologic Disorder with a Positive P-ANCA

A

Churg-Strauss vasculitis

44
Q

Human Leukocyte Antigen (HLA-B27)

A

Ankylosing spondylitis
Reactive arthritis
Enteropathic spondylitis
Psoriatic spondylitis

45
Q

Diagnosing Ankylosing Spondylitis

A

Inflammatory back pain of insidious onset, worse in the morning, better with exercise & NSAIDs
Radiographic evidence
HLA-B27 positive

46
Q

Relative Contraindications of Arthrocentesis

A

Overlying skin infection

Bleeding diathesis

47
Q

Complications of Arthrocentesis

A

Infection
Bleeding
Cartilage injury
Vasovagal episode

48
Q

Define Uric Acid

A

By-product of purine (adenine, guanine) catabolism

49
Q

2 Mechanisms of Hyperuricemia

A

Increased production

Decreased excretion

50
Q

Reasons for Increased Production of Uric Acid

A
Dietary purines (meat, yeast/beer, beans)
Endogenous purine synthesis (CA)
Tissue nucleic acid breakdown (chemo, hemolysis)
51
Q

Reasons for Decreased Excretion of Uric Acid

A

Renal failure
Inhibition of tubular rate secretion (ketoacidosis)
Enhanced tubular rate reabsorption (diuretics, insulin resistance, dehydration)

52
Q

Uric Acid Increased by What Medications

A

Low-dose ASA
ETOH
Caffeine
Vitamin C

53
Q

Uric Acid Decreased by What Medications

A

High-dose ASA
Estrogens
Corticosteroids

54
Q

Clinical Significance of Elevated Uric Acid

A
Gout
Asymptomatic hyperuricemia
Renal impairment
Toxemia of pregnancy
Conditions associated with increased production
55
Q

Define Gout

A

Joint pain with swelling & erythema

Deposition of sodium urate crystals in joints & tissues

56
Q

Parts of CREST Syndrome

A
Calcinosis
Raynaud's
Esophageal dysmotility
Sclerodactyly
Telangectasias
57
Q

Systemic Sclerosis Characterized by

A

Functional & structural abnormalities of small blood vessels, fibrosis of skin & organs, & autoantibodies

58
Q

Sjogren’s Syndrome Characterized by

A

Diminished lacrimal & salivary gland secretion (sicca syndrome)

59
Q

Define Mixed Connective Tissue Disorder (MCTD)

A

Syndrome of overlapping disease manifestations with features of RA, SLE, scleroderma, & polymyositis

60
Q

Define Dermatomyositis

A

Inflammatory myopathy with cutaneous lesions & muscle pain & weakness

61
Q

Polymyositis Characterized by

A

Progressive muscle pain & weakness