Friday, September 27, 2013

USMLE Step 1 Exam - Everything You Need To Know About Rheumatoid Arthritis

The USMLE Step 1 exam is going to test your ability to understand the basic sciences, but as we move forward the exam is become more and more clinical in nature, so it is essential that you learn how to combine the basic sciences with the clinical side of medicine. When it comes to Rheumatoid Arthritis on the Step 1 exam, there are a few important things you have to understand, namely: Main signs and symptoms, clinical findings, lab findings, and finally when and which medications to use to help you patient.

Here are the main topics we are going to cover to ensure your USMLE Step 1 theory for rheumatoid arthritis is covered completely:

1. The main signs and symptoms

2. The main extra-articular signs and symptoms

3. The expected lab findings of RA

4. The steps to proper management for RA

5. Important complications you must be aware of relating to RA

The Main Signs and Symptoms:

  • Morning stiffness that lasts more than 1hr for at least 6 weeks

  • Swelling of the wrists, PIP, or MCP joints for at least 6 weeks

  • Symmetric joint swelling for at least 6 week

  • Swelling of at least 3 joints for at least 6 weeks

Deformities involving the PIP and DIP joints include "Boutonniere deformity" and "Swan-Neck deformity". The Boutonniere deformity is flexion of the PIP and extension of the DIP, while the Swan-Neck deformity is PIP extension with DIP flexion.

The Main extra-articular signs and symptoms

  • Rheumatoid nodules (subcutaneous nodules)

  • Caplan syndrome (rheumatoid nodules in the lungs)

  • Tendon and ligament damage

The expected lab findings of RA:

  • Rheumatoid Factor is increased

  • Anemia is usually found

  • ESR is increased (due to inflammatory process)

  • X-ray may show bony erosions

  • Synovial fluid analysis looking at white blood cell count (should be elevated)

The steps to proper management of RA:

We used to keep NSAIDs as the drug of choice, but now we stick to using Methotrexate as the first line management. Here are the steps to proper management:

  • Use methotrexate for 1 week, then add prednisone for 1 week (using prednisone subsequently for flare-ups)

  • If your patient cannot use methotrexate, we can give them hydroxychloroquine instead, which is an anti-malarial. This drug has the ability to cause retinopathies, so we have to ensure they get regular eye exams.

Important complications you must be aware of in RA:

  • An extension of the inflamed synovium into the popliteal space can cause a Baker's cyst, which presents with a swollen, tender, and painful calf

  • Prior to any surgical procedure, it is important to rule out a subluxation of the atlantoaxial joint, which can accidentally be hyperextended during intubation and potentially lead to post-operative paralysis.

Understanding and following the high-yield rheumatoid arthritis information above will ensure you cover all the RA information you need for your USMLE Step 1 exam.

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