Lab Tests in Rheumatic Disease

Question 1

CRP

Answer 1

Acute phase reactant
Non-specific opsonin for bacteria
Useful marker of acute inflammation
Causes include infection, RA, PMR, systemic vasculitis, CTD

Question 2

ESR

Answer 2

Measure of the rate o fall of RBCs
Normally red cells fall slowly, leaving little clear plasma
Increased blood levels of certain proteins (ex fibrinogen or Igs) cause the red blood cells to fall more rapidly, increasing the ESR

Question 3

Examples of systemic autoimmune rheumtic diseases

Answer 3

RA

CTD (SLE, mixed CT disease, Sjogrens, systemic sclerosis, dermatomyositis)

Question 4

2 lab tests that may be positive in RA

Answer 4

RF

Anti-CCP

Question 5

What lab tests are most useful for SLE?

Answer 5

ANA

Anti-dsDNA

Question 6

ENA

Answer 6

Extractable Nuclear Antigen AB
Used in SLE
Antigens that are present in nucleus of cells

Question 7

What test to order for suspected small vessel vasculitis?

Answer 7

ANCA

Question 8

Antiphospholipid syndrome

Answer 8

Autoimmune hypercoagulable state related to antiphospholipid antibodies
Diagnosed via clinical events and antiphospholipid antibodies (lupus anticoagulant, anticardiolipin)

Question 9

Polymyalgia rheumatica

Answer 9

Syndrome of pain/stiffness
Usually neck, shoulders, upper arms and hips, but may occur all over the body
Can be associated with temporal arteritis
No definitive lab test but CRP or ESR are used