Ct-Ms - 2-24 - Lab Testing

Front 1

32 year old female presents with generalized malaise, fatigue, intermittent low grade fever. Has noted Raynaud’s phenomenon, stiffness in her hands in the morning, facial rash, and sensitivity to sun exposure.

Exam is notable for malar rash and synovitis.

You are allowed to draw one lab test….

Back 1

ANA (thinking lupus)

Front 2

65 year old man has been diagnosed with polymyalgia rheumatica (PMR) and has been successfully treated with prednisone for 6 months. Last week he had tapered his prednisone down to 7.5 mg from 10 mg and he thinks he is feeling stiff in his shoulders and hips especially first thing in the AM.

He asks you if he should go back up on the prednisone dose.
You send him to get a blood test...

Back 2

Sed rate or CRP

Front 3

20 year old veteran from Iraq was recently diagnosed with polymyositis after noticing progressive muscle weakness in his arms and legs. He has started to gain some of his strength back with the combination of prednisone and azathioprine.

He ask you about the long term course of this condition and his prognosis.
Is there any way to get more information about his prognosis?

Back 3

Jo-1 antibodies to give px

Front 4

Diagnostic tests

Back 4

ANA, RF, ANCA

Front 5

Px tests

Back 5

dsDNA, RF, Jo-1 antibody

Front 6

Evaluative tests

Back 6

ESR, C-reactive protein.

Note that these are increased in many situations, so they aren't good to make dx.

Front 7

Specificity

Back 7

Negative in health

When positive, you rule in a disease.

(e.g. C-ANCA and Wegener's)

Front 8

Sensitivity

Back 8

Positive in disease

When negative, you rule out a disease.

Front 9

With less prevalence of a disease...

Back 9

Less PPV and higher NPV!

This is because you are sampling more people who really don't have the disease!!!

Sens and spec of the test doesn't change though.

Front 10

Rheum factor

Back 10

Neither sens or specific.

Ab against Fc portion of another Ig.

It represents the degree of activation of the immune system.

Front 11

Big list of things associacted with RF

Back 11

Rheumatoid arthritis
Systemic lupus erythematosus
Sjögren's syndrome
Systemic sclerosis
Dermatomyositis/polymyositis
Vasculitis
Cryoglobulinemia
Juvenile rheumatoid arthritis

Normal indiv
elderly
bac infections
Viral inf (espec parvovirus!!!)
Parasites.

Lymphoproliferative disease
Interstitial lung disease
Chronic liver disease
Sarcoidosis
Post-vaccination
Malignancies

Front 12

Anti-CCP

Back 12

ELISA to detect filaggrin derived from human skin or synthetic peptides.

Same sens as RF but high spec (for RA)

Good for early inflamm arthritis and bodes poor px

Front 13

Anti-nuclear antibody (ANA)

Back 13

Against a nuclear protein.

Dx, px or evaluative test

Front 14

Mech of ELISA

Back 14

coat a surface with antigen. add pts serum. and enzme conjugate and substrate which will fluoresce if positive.

Front 15

Antinuclear antibody patterns

Back 15

Anti-centromere - important in dx CREST variant of systemic sclerosis. Also can be seen in Raynaud's

Anti-nucleolar - also in systemic sclerosis.

Front 16

Native DNA test and Sm (small nuclear RNA protein) test

Back 16

Big in lupus

Front 17

SS-A/Ro test

Back 17

For RNA-protein complex.

Big in pregnant pts and lupus because it is px for conduction defects in the newborn.

Front 18

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

Back 18

Myositis associated antibodies

interstitial lung disease, mechanic's hands and Raynaud's phenomenon.

Front 19

Anti-SRP (signal recognition protein)

Back 19

Myositis associated antibodies

Abs to this is a very bad. Poor px.

Front 20

Scleroderma associated antibodies

Back 20

Scl-70 - diffuse sclerosis or interstitial lung disease.

Anti-centromere antibodies More risk of pulmonary HTN, CREST scleroderma and limited disease.

Front 21

antibodies to neutrophil cytoplasmic antigens.

Back 21

c-ANCA for Wegener's and p-ANCA for polyangiitis and pauci-immune glomerulonephritis.

Front 22

ESR

Back 22

Westergren method - With inflammatory state, there are many proteins with + charge which then attach to RBCs with - charge. So now the RBCs clump less and they drop through the plasma more quickly.

An evaluative test.

Front 23

Rule of thumb for ESR

Back 23

Men should be no greater than age/2.

Women - (age+10)/2

Front 24

ESR > 100

Back 24

medical emergency - think of giant cell arteritis.

Front 25

24 year old male medical student presents to Dick’s House
reporting 1 week history of arthralgias, myalgias, and fatigue. Got sunburned last weekend while at the Skiway trying to set hill record for most runs before noon. Exams are fast approaching…He’s currently studying for CT/Bone. Housemate who works at Cradle and Crayon has been under the weather lately.

ROS: neg for alopecia, mouth sores, Raynaud’s.

Fam Hx: Mother has Raynaud’s

Exam: tanned in sun exposed areas some peeling
neg heart and lung exam, no synovitis

Back 25

Pretest prob of something bad in this pt is low.

Tell him to take it easy for a little.

Front 26

34 year old female accountant presents to the Lyme Road Clinic where you are with your On Doctoring preceptor.
She reports several weeks of malaise, arthralgias, fatigue. Her hands feel stiff in the morning and better after a shower. Having trouble keeping up with demands of work and family. No recent illnesses or similar episodes. Maybe a fever. Gets a mouth sore every now and then.

ROS: neg for alopecia or sicca sxs (dry eyes/mouth)
Has had Raynauds’ for years.
Had one first term miscarriage. 3 subsequent uneventful pregnancies

Fam Hx: Mother has Hashimoto’s thyroiditis

Exam: fatigued appearing not toxic
livedo reticularis findings in legs – blueish netlike pattern in lower extremities.
heart and lung exam normal
synovitis in MCPs

Back 26

Malaise – not feeling well.
Sed rate comes back at 50 let’s say.
dsDNA

Something immunologically – hashimotos in mom, mouth sores, low grade fevers. Swelling

Thinkign of lupous bc swelling in symm small joint inflamm pattern.

Front 27

45 year old female software engineer presents to the DHMC ER with dyspnea and chest pain of several hours duration.
She reports several weeks of fevers, malaise, arthralgias, fatigue.She has had progressive swelling of her lower legs over the last 2 weeks. She tried to get some sun the other day but got really sick. Has had a facial rash and mouth sores. Increasingly short of breath for 2 days with chest pain when she breathes in deeply.

ROS: + sicca sxs, DVT in left arm 10 years ago
Has had Raynauds’ for years.
One uneventful pregnancy

Fam Hx: Mother died of massive PE in her 30’s
Sister with SLE

Exam: BP 100/50 HR 120 pulse ox 92 % tachypnic
Malar rash
CVP 12 cm

Exam: BP 100/50 HR 120 pulse ox 92 % tachypnea mod distress
HEENT: Malar rash
CVP 12 cm
HEART: tachy reg muffled diffuse
LUNGS: dull at right base, pleural based rub auscultated
EXT: 2+ pitting edema in both legs up to knees


Labs: leukopenic, anemic, thrombocytopenic
renal insufficiency
urinalysis with 4+ protein

Echocardiogram: pericardial effusion

CXR: right pleural effusion

Back 27

DVT in left arm – very strange.

Weird clots – must think of antiphosphlipid antibodies.

SLE.

This is full blown lupus – the ANA might be negative!

This is full blown lupus.
Tamponade explains all her CV findings.

Front 28

Take home points

Back 28

Let clinical impression guide testing

Estimate PPV

Don't use these tests for screening

Don't order test if you don't understand its performance characteristics.

Don't order test if it's results won't change course for additional dx or tx

Never order test without first performing a thorough rheum history and physical

Don't order panel of tests unless timing is critical