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PMR vs GCA for MRCP Part 1

TL;DR

Polymyalgia Rheumatica vs. Giant Cell Arteritis is a classic high-yield pairing for MRCP Part 1. PMR presents with proximal stiffness and raised inflammatory markers, while GCA is a large-vessel vasculitis causing headache, jaw claudication, and risk of blindness. Both conditions are closely related and steroid-responsive, but GCA requires urgent treatment to prevent irreversible complications.


Why this matters

In MRCP Part 1, rheumatology questions frequently test pattern recognition through short clinical vignettes. Polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) are often examined together because they share epidemiology and pathophysiology but differ critically in severity and complications.

A candidate who can quickly distinguish between the two—especially recognising when GCA is a medical emergency—will gain easy, high-yield marks. For a structured preparation strategy, see the MRCP Part 1 overview.


Core sections

1. Definition and Pathophysiology

  • Polymyalgia Rheumatica (PMR): An inflammatory condition causing pain and stiffness in proximal muscle groups, particularly shoulders and hips. The underlying mechanism is immune-mediated inflammation.

  • Giant Cell Arteritis (GCA): A granulomatous vasculitis affecting large and medium-sized arteries, especially branches of the external carotid artery (e.g., temporal artery).

🔑 Key association:

  • Around 40–50% of GCA patients have PMR symptoms

  • Approximately 10–20% of PMR patients develop GCA

2. Epidemiology (Exam Favourite)

  • Age >50 years (almost never occurs below this age)

  • Female predominance

  • More common in individuals of Northern European descent

💡 Exam tip: Any elderly patient with systemic inflammation should trigger consideration of PMR or GCA.

3. Clinical Features: Side-by-Side Comparison

Feature

Polymyalgia Rheumatica (PMR)

Giant Cell Arteritis (GCA)

Pain

Shoulder & hip girdle stiffness

Temporal headache

Morning stiffness

>45 minutes (prominent)

May occur

Muscle weakness

Absent (pain-limited)

Absent

Systemic features

Fatigue, low-grade fever

Fever, weight loss

Cranial symptoms

Absent

Jaw claudication, scalp tenderness

Vision

Normal

Visual loss risk

ESR/CRP

Elevated

Markedly elevated

🔑 High-yield pearl: Jaw claudication is the most specific symptom of GCA.

4. Investigations

  • ESR/CRP: Elevated in both conditions

  • Creatine kinase (CK): Normal in PMR (distinguishes from myositis)

  • Temporal artery biopsy (TAB): Gold standard for GCA

  • Ultrasound: “Halo sign” suggests GCA

⚠️ Critical rule: Do not delay steroid treatment in suspected GCA while awaiting biopsy.

5. Management

Polymyalgia Rheumatica

  • Prednisolone 10–20 mg daily

  • Rapid improvement within days (diagnostic clue)

  • Gradual taper over months

Giant Cell Arteritis

  • Prednisolone 40–60 mg daily immediately

  • IV methylprednisolone if visual symptoms

  • Consider aspirin

  • Tocilizumab for refractory cases

👉 Practise treatment-based questions in Free MRCP MCQs.

6. Complications

  • PMR: Rarely life-threatening

  • GCA:

    • Irreversible vision loss (anterior ischaemic optic neuropathy)

    • Stroke

    • Aortic aneurysm

🚨 Most tested complication: Vision loss

7. Diagnostic Clues (Rapid Recall)

PMR

  • Bilateral shoulder pain

  • Morning stiffness >45 minutes

  • Age >50

  • Raised ESR

  • Dramatic steroid response

GCA

  • New headache

  • Temporal artery tenderness

  • Jaw claudication

  • Visual disturbance

  • Positive biopsy

8. High-Yield Summary Checklist

  1. Age >50 → think PMR/GCA

  2. Shoulder stiffness → PMR

  3. Headache + jaw pain → GCA

  4. Normal CK → PMR (not myositis)

  5. Raised ESR → both

  6. Visual symptoms → emergency GCA

  7. Start steroids before biopsy

  8. PMR responds to low-dose steroids

  9. GCA requires high-dose steroids

  10. PMR and GCA frequently coexist

Late-night MRCP Part 1 study session focusing on rheumatology topics polymyalgia rheumatica and giant cell arteritis

Practical examples / mini-cases

Case 1 (PMR)

A 70-year-old woman presents with bilateral shoulder stiffness worse in the morning, lasting over 1 hour. ESR is elevated; CK is normal.

Answer: Polymyalgia rheumatica Explanation: Classic proximal stiffness with raised inflammatory markers and normal CK.

Case 2 (GCA)

A 75-year-old man presents with headache, scalp tenderness, and pain while chewing. ESR is 100 mm/hr.

Answer: Giant cell arteritis Explanation: Jaw claudication is highly specific. Immediate steroid therapy is required to prevent blindness.

👉 Test your understanding with a Start a mock test.


Common pitfalls

  • Confusing PMR with polymyositis (CK is normal in PMR)

  • Delaying steroids in suspected GCA

  • Missing jaw claudication as a diagnostic clue

  • Assuming absence of headache excludes GCA

  • Forgetting PMR–GCA association


FAQs

1. Can polymyalgia rheumatica occur without GCA?

Yes. Most PMR patients do not develop GCA, but clinicians must screen for GCA symptoms regularly.

2. Why is giant cell arteritis an emergency?

Because it can cause irreversible vision loss due to ischaemic optic neuropathy. Immediate steroid treatment is essential.

3. How do you differentiate PMR from myositis?

PMR has normal CK and no true muscle weakness, whereas myositis shows elevated CK and proximal weakness.

4. Is temporal artery biopsy always positive?

No. Skip lesions can cause false negatives, so diagnosis remains clinical.

5. What steroid doses are used?

PMR: 10–20 mg prednisolone daily.GCA: 40–60 mg (or IV if visual symptoms).


Ready to start?

Understanding high-yield comparisons like PMR vs GCA is essential for MRCP success. Strengthen your preparation with:


Sources

 
 
 

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