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Flashcards in Diagnostics Deck (61)
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1

How to diagnose a rheumatological disease?

H&P
Labs/radiographic findings- confirmatory

2

Define Sensitivity

Proportion of patients with positive test who have the disease

3

Define Specificity

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

4

H&P in Rheumatologic Diseases

Increase "pretest probability" with history
Look for clues on physical exam

5

When to Order Serologic Tests

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

6

Define Acute Phase Reactants

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

7

Define Erythrocyte Sedimentation Rate (ESR)

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

8

ESR Measurement

Indirect measurement of serum acute phase reactant concentrations

9

ESR Influenced by

Size
Shape
Number of RBCs

10

ESR Increased by

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

11

ESR in Polymyalgia Rheumatica

ESR >40 mm/hr

12

ESR in Giant Cell Arteritis

ESR >90 mm/hr

13

Define C-Reactive Protein (CRP)

Acute phase protein produced by the liver

14

What is CRP produced in response to and enhance?

Produced in response to inflammation
Enhances complement binding & phagocytosis

15

What does CRP measure?

Direct measure of acute phase reactants

16

Pros & Cons of CRP

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

17

Define Rheumatoid Factor

Auto antibody directed against Fc portion of IgG

18

Conditions Causing Positive Rheumatoid Factor

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

19

Define Post Test Probability

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

20

How is rheumatoid factor measured?

Less than 1:80 is negative

21

Anti-CCP (citrulline antibody)

Antibody directed against "citrullinated" peptide residues present within inflammatory sites

22

Anti-CCP vs. RF

Sensitivity equal
Specificity: anti-CCP > RF

23

Anti-Nuclear Antibodies (ANA)

Autoantibodies directed at nuclear antigens or content of the cell nucleus

24

What is a serologic hallmark of systemic autoimmune disease?

ANAs

25

Uses of ANA

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

When is a positive ANA seen?

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

27

Non-Rheumatic Conditions Causing Positive ANA

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

28

Criteria for Classification of SLE (Need 4+)

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

When to Order an ANA

Moderate pre-test probability: 3/11 lupus criteria

30

ANA Specific Autoantibody Tests

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)