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Flashcards in Dz Testing Deck (21)
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1
Q

What are the two key features in dx of any rheumatologic disorder?

A

Dx is based upon the clinical features (criteria for classification) and laboratory/radiographic findings.

Diagnostic test do not make the dx

2
Q

Discuss sensitivity and specificity.

A

Sensitivity: proportion of pts with a + test who have the dz.

SNOUT: so a negative test will effectively rule out the dz.

Specificty: proportion of pts with a negative test who do not have the dz

SPIN: so a positive test will effectively rule in a dz.

3
Q

How do i screen for an autoimmune dz?

When do I order serologic tests?

A

Primarily by Hx and Physical… increases your PRETEST PROBABILITY*

You should have compelling reason (mod-high pretest probability) to order rheumatologic evalution

4
Q

Acute Phase Reactants:

  • what are these and where are they produced?
  • cause
  • examples
  • use
A

What: proteins synthesized by the liver

Cause:

  • inflammation….from infection, autoimmune disorders*, neoplasma
  • tissue injury/necrosis from trauma and infarction
  • these proteins go up and down with inflammation.

Examples:

  • Coagulation proteins (I, II) fibrinogen levels increase, platelets increase
  • C-reactive protein
  • Complement (C3, C4, B)
  • Others: fibronectin, transport proteins (Haptoglobin, Transferrin, ceruloplasmin)

Use:

  • monitors dz activiy
  • NOT Diagnostic
5
Q

Erythrocyte Sedimentation Rate:

  • definition
  • pathophys of normal ESR
  • pathophys of abnormal ESR
  • influenced by what 3 factors
A

Def: the distance at which erythrocytes have settled in a vertical column of anticoagulated blood in an hour.

Patho Normal ESR:
-RBC repel one another d/t electrostatic forces (neg charges). They settle in a tube at a certain rate.

Patho Abnormal ESR:

  • positively charged acute phase proteins neutralize negative charges and allow RBC to aggregate, now the RBC fall at a different rate and at a further distance.
  • inflammatory states increase ESR.*
  • *As pt condition changes the ESR changes relatively slowly**

Influenced by size, shape, and number of RBC (ex. ESR is increased in anemia)

6
Q

ESR:

  • T/F, ESR values decrease with age?
  • T/F, ESR is higher in women?
  • what are normal values in men, women, and children.
  • How do we correct ESR for age in men and women?
A

False, ESR values increase with age.

True, ESR is higher among women.

Normal:

  • men less than 17mm/hr
  • women less than 24mm/hr
  • children less than 10mm/hr

Age correction:
-men: upper limit of normal ESR = age/2

-women: upper limit of normal of ESR = (Age +10)/2

7
Q

What two rheumatic conditions is ESR diagnostic of? Utility in other inflammatory diseases?

A

Polymyalgia rheumatica (ESR greater than 40mm/hr)

Giant cell arteritis (ESR greater than 90mm/hr)

Utility in other dz:
-limited utility for differentiating inflammatory joint dz from noninflammatry joint dz….nondiagnostic**

8
Q

C-Reactive Protein (CRP):

  • what is this and where is this produced?
  • how does this compare to ESR?
  • what is normal?
A

What: an acute phase reactant produced in the liver.

Comparison:
-less sensitive than ESR (age, gender, anemia), responds more quickly, but we dont always know how to interpret.

Normal CRP: less than 1 mg/L…anything higher than this is abnormal!

9
Q

T/F, ESR and CRP are nonspecific indicators of inflammation, are not used in screening for rheumatic dz, and cannot differentiate one dz from another?

A

True.

10
Q

Rheumatoid Factor:

  • what is this?
  • what are some conditions causing positive Rheumatoid factor?
  • is this test diagnostic for RA?
A

Rheumatoid Factor: an auto-aby directed against Fc portion of IgG

+ rheumatoid factor:

  • Rheumatoid Arthritis
  • SLE
  • Scleroderma
  • Sjogren
  • Cryoglobulinemia
  • infections: hepatitis, TB, SBE, Syphilis, viral illness (mon)
  • Pulmonary dz (sarcoidosis)
  • Malignancy
  • Lots of RF are false positives*

NO! it is not diagnostic for RA on its own, if you have a high pretest probability and + RF then your post test probability is markedly increased and this can make the dx.

11
Q

What is the 2010 ACR classification Criteria of RA?

A

Need a total score of at least 6

  • Number of synovial joints
  • -2-10 large joints = 1 point
  • -1-3 small joints = 2 points
  • -4-10 small joints = 3 points
  • -more than 10 joints = 5 points

Serological abnormality:

  • Low positive (above Upper limits of Normal) = 2 points
  • high positve (greater than 3x the upper limit of normal) = 3 points

Elevated acute phase proteins (CRP or ESR) above the ULN = 1 point

Sx duration of at least 6wks = 1 point

12
Q

Do we retest RF in pts with established RA?

A

No, once the test is positive there is no value in retesting, RF does not change with dz activity

13
Q

Anti-CCP (citrulline aby)

  • what is this?
  • MC associated with what disorder?
  • how does this compare to RF?
A

What: aby directed against citrullinated peptides residues present within inflammatory sites.

MC associated with RA

Sensitivity equivalent to RF, greater specificity than RF. THIS IS USEFUL WHEN RF IS NEGATIVE.

14
Q

Anti-nuclear abys (ANA)

  • what is this?
  • use
  • reasons for positive ANA?
  • when should i order an ANA?
A

Autoabys directed against nuclear ags, serologic hallmarks of systemic autoimmune disease.

Use:

  • provide further diagnostic and prognostic data concerning pts who have minimal sx or who have clinical features of more than 1 autoimmune dz.
  • monitor dz activity

Positive ANA:

  • systemic autoimmune dz
  • organ specific immune dz (hashimotos thyroiditis, graves dz, autoimmune hepatitis)
  • infections (mono, hep c, SBE, HIV)
  • normal ppl (false positives are generally low titiers and MC in elderly women)

Order an ANA when your pre-test probability for SLE is moderate. NOT used as random screening. ALso, not useful to dx other conditions but may support clinical dx..

15
Q

There are different types of ANAs defined by their target Ag, what are these tests and what disease are they used for?

A

Anti-dsDNA: specific for SLE.

Anti-Sm (Smith antigen): highly specific for SLE

Anti-centromere aby (ACA): associated with CREST and scleroderma

Anti-topoisomerase I (Scl-70)- associated with diffuse scleroderma

Anti-Ro (SS-A) and La (SS-B): associated with Sjogrens

Anti-U1 snRNP: mixed connective tissue dz

Anti-Jo-1: myositis associated with interstitial lung dz. Raynauds

16
Q

Serum complements:
-use

Antineutrophil cytoplasmic abys (ANCA)
-MC associated with what disorder?

A

Complement Use: monitoring dz activity in SLE. (C3 and C4 will be low demonstrating active SLE)

ANCA:

  • most strongly associated with vasculitis
  • c-ANCA = wegeners granulomatosis and microscopic polyangitis
  • p-ANCA = Churg-Strauss vasculitis
  • ANCA alone is not diagnostic for vasculitis, if not positive consider dx other than vasculitis
17
Q

Human Leukocyte Ag (HLA-B27):

-MC associated with what syndromes?

A

MC associated with

  • Ankylosing spondylitis*****
  • Reactive arthritis (Reiters syndrome)
  • Enteropathic spondylitis
  • Psoriatic spondylitis
18
Q

Arthrocentesis:

  • synovial fluid analysis
  • normal fluid analysis
A

analysis: routine studies
- appearance = color, turbidity, viscosity, quantity
- cell counts: leukocyte, erythrocyte, and differential cell counts
- culture
- protein
- glucose
- mucin clot

Analysis: 
-Volume: less than 3.5ml 
-Clarity: transparent
-Color: color 
-Viscosity: high 
-WBC: less than 200 
Culture: negative 
-Total protein: 1-2 
Glucose: nearly equal to blood.
19
Q

Uric Acid:

  • what is this?
  • critical values
  • mechanisms of hyperuricemia
  • drug effects of uric acid levels
A

What: by product of purine

Critical value: greater than 12mg/dL

Mech:

  • increased production = dietary purines (meat, yeast/beer), endogenous purine synthesis (CA)
  • decreased excretion = renal failure

Drug effects:
-Uric acid increased by: low dose ASA, ETOH, caffeine, Vit C

-uric acid decreased: high dose ASA, estrogen, corticosteroids

20
Q

What is the clinical significance of elevated uric acid?

Is XRAY used in gout?

A

Gout! Renal impariment. Toxemia in pregnancy

yes, XRAY may be used for gout.

21
Q

Serologic tests for rheumatologic dz are supportive rather than diagnostic.

A

.