During a routine clinic visit, a 71-year-old woman describes a 6-week history of profound … — USMLE Step 2 CK

During a routine clinic visit, a $71$ -year-old woman describes a $6$ -week history of profound stiffness in her shoulders, neck, and pelvic girdle. She reports that the stiffness is most severe upon awakening and typically lasts for $2$ to $3$ hours before gradually improving throughout the day. Over the past month, she has also experienced generalized fatigue and a $2$ -kg ( $4.4$ -lb) weight loss. She explicitly denies headaches, visual changes, scalp tenderness, and jaw pain with chewing. Her past medical history is notable for mild essential hypertension. Vital signs are within normal limits.

Physical examination reveals a well-appearing but visibly uncomfortable woman. There is no focal joint effusion, erythema, or warmth. Active range of motion in the shoulders and hips is limited by pain, but passive range of motion is fully preserved. Muscle strength is $5/5$ in the proximal and distal extremities.

Laboratory studies show:

Test	Result	Reference Range
Hemoglobin	$10.8$ g/dL	$12.0$ - $15.5$ g/dL
Leukocyte count	$7,500$ /mm $^3$	$4,500$ - $11,000$ /mm $^3$
Erythrocyte sedimentation rate	$88$ mm/h	$0$ - $20$ mm/h
Creatine kinase	$85$ U/L	$40$ - $150$ U/L
Thyroid-stimulating hormone (TSH)	$2.4$ $\mu$ U/mL	$0.5$ - $5.0$ $\mu$ U/mL

Which of the following is the most appropriate next step in the management of this patient?

A
Perform a temporal artery biopsy
B
Administer intravenous ceftriaxone
Initiate low-dose oral prednisone therapyAnswer
D
Initiate levothyroxine therapy
E
Initiate fluoxetine therapy

Answer

Initiate low-dose oral prednisone therapy

The correct answer is to initiate low-dose oral prednisone therapy. This patient presents with the classic clinical triad for polymyalgia rheumatica (PMR): age greater than

50

years, bilateral aching and morning stiffness (lasting

>1

hour) in the proximal joint girdles (shoulders, neck, hips), and an elevated erythrocyte sedimentation rate (ESR). Furthermore, her normal creatine kinase level distinguishes this condition from inflammatory myopathies like polymyositis, where muscle weakness (rather than just pain-limited movement) and elevated muscle enzymes are prominent. Because she lacks any cranial symptoms (such as new-onset headache, visual disturbances, or jaw claudication), there is no clinical suspicion for concurrent giant cell arteritis (GCA). The gold-standard treatment for isolated PMR is low-dose oral glucocorticoids (e.g.,

10

20

mg of prednisone daily), which typically results in rapid, dramatic symptom relief within

24

72

hours.

Step-by-Step Solution

Analyze the patient's demographic and clinical presentation.

A woman over age

50

presents with symmetric aching and prolonged morning stiffness (

>1

hour) in the shoulders and pelvic girdle, alongside systemic symptoms like fatigue and weight loss.

These are the hallmark clinical features of polymyalgia rheumatica (PMR).

Evaluate for 'red flag' symptoms of related conditions.

The patient explicitly denies headache, visual changes, scalp tenderness, and jaw claudication.

This rules out concurrent giant cell arteritis (GCA), meaning the patient has isolated PMR.

Interpret the laboratory findings to rule out mimics.

The ESR is markedly elevated (

88

mm/h), confirming systemic inflammation. Creatine kinase and TSH are normal.

Normal CK rules out inflammatory myopathies (e.g., polymyositis), and normal TSH rules out hypothyroid myopathy.

Determine the standard pharmacological intervention.

Select low-dose oral prednisone (

10

20

mg/day).

Isolated PMR is highly responsive to low-dose glucocorticoids, which serve as both a diagnostic aid and the primary treatment.

Key Concept

Diagnosis and management of isolated polymyalgia rheumatica (PMR)

Estimated Time:1m 15s

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