Examkin

Question

Difficulty: MediumOrdering Laboratory Tests

Match each patient's clinical presentation to the most appropriate targeted diagnostic laboratory test.

  • Female, age 32, presenting with 4 months of bilateral metacarpophalangeal joint swelling and significant morning stiffness lasting over two hours.Anti-cyclic citrullinated peptide (anti-CCP) antibodies
  • Female, age 45, reporting a gritty sensation in both eyes and needing to drink water constantly to chew food, noting enlarged parotid glands.Anti-Ro/SSA and anti-La/SSB antibodies
  • Female, age 28, hospitalized for an unprovoked deep vein thrombosis; obstetric history is notable for two spontaneous fetal losses at 16 and 18 weeks gestation.Lupus anticoagulant and anticardiolipin antibodies
  • Female, age 40, exhibiting thickened skin isolated to the fingers, episodes of severe digital pallor in the cold, and symptoms of chronic gastroesophageal reflux.Anti-centromere antibodies

Answer

1) Symmetric MCP arthritis matches Anti-cyclic citrullinated peptide antibodies. 2) Dry eyes and dry mouth matches Anti-Ro/SSA and anti-La/SSB antibodies. 3) Recurrent miscarriages and DVT matches Lupus anticoagulant and anticardiolipin antibodies. 4) Thickened skin on fingers, Raynaud phenomenon, and heartburn matches Anti-centromere antibodies.
Each clinical vignette provides a classic presentation of a specific rheumatologic or autoimmune condition that requires targeted laboratory evaluation to confirm the diagnosis. Rheumatoid arthritis is confirmed with highly specific anti-CCP antibodies. Sjögren syndrome is characterized by sicca symptoms and is associated with anti-Ro/SSA and anti-La/SSB antibodies. Antiphospholipid syndrome presents with thrombosis and pregnancy loss, requiring lupus anticoagulant and anticardiolipin antibody testing. Limited cutaneous systemic sclerosis (CREST syndrome) presents with Raynaud phenomenon, sclerodactyly, and esophageal dysmotility, and is strongly associated with anti-centromere antibodies.

Step-by-Step Solution

1
Analyze the first clinical vignette to identify the most likely underlying diagnosis.
The patient with symmetric MCP joint swelling and prolonged morning stiffness has a classic presentation of rheumatoid arthritis (RA).
Recognizing the pathognomonic clinical features of RA allows for the selection of its most specific diagnostic laboratory marker.
2
Determine the most specific initial laboratory test for the suspected diagnosis of RA.
Anti-cyclic citrullinated peptide (anti-CCP) antibodies are selected for the first vignette.
While rheumatoid factor is sensitive, anti-CCP is highly specific for RA and is the most appropriate targeted test to confirm the diagnosis.
3
Analyze the second vignette (sicca symptoms and parotid enlargement) to identify the diagnosis and required test.
The clinical picture is highly suggestive of Sjögren syndrome, warranting testing for Anti-Ro/SSA and anti-La/SSB antibodies.
Identifying the autoimmune exocrinopathy directs testing toward its specific diagnostic autoantibodies.
4
Evaluate the third vignette (thrombosis, mid-trimester miscarriages) to determine the necessary lab workup.
The presentation is characteristic of antiphospholipid syndrome (APS), requiring Lupus anticoagulant and anticardiolipin antibody testing.
Recognizing the combination of unprovoked venous thrombosis and pregnancy morbidity is critical for guiding the serologic evaluation of APS.
5
Analyze the fourth vignette (sclerodactyly, Raynaud phenomenon, GERD).
The patient has limited cutaneous systemic sclerosis (CREST syndrome), which requires testing for Anti-centromere antibodies.
Identifying this specific scleroderma variant guides the selection of the correct diagnostic and prognostic autoantibody.

Key Concept

Targeted autoantibody testing in rheumatologic and autoimmune diseases
Rate this question

Topics

Ordering Laboratory Tests

More questions from this topic