AANP Family Nurse Practitioner (FNP) Certification ExamAssessmentMedium
A 45-year-old female presents with a 6-month history of progressive fatigue, generalized weakness that worsens with activity and improves with rest, and occasional double vision. On examination, she has ptosis of the right eyelid and mild facial asymmetry. Which diagnostic test would be most specific for confirming the suspected diagnosis?
- AElectromyography (EMG) with nerve conduction studies
- BAcetylcholine receptor (AChR) antibody test
- CThyroid Stimulating Hormone (TSH) level
- DMagnetic Resonance Imaging (MRI) of the brain
Show answer & explanationAnswer & explanation
Correct answer: B. Acetylcholine receptor (AChR) antibody test
The patient's symptoms (fatigue, fluctuating muscle weakness, ptosis, double vision) are highly suggestive of Myasthenia Gravis. The acetylcholine receptor antibody test is highly specific for this autoimmune disorder.
Why the other options are wrong
- A. EMG with nerve conduction studies can show abnormalities in Myasthenia Gravis (e.g., decremental response), but the antibody test is more specific for initial diagnosis.
- C. TSH would be indicated for fatigue but does not explain the specific muscle weakness patterns or ocular symptoms.
- D. MRI of the brain would be appropriate for neurological symptoms but is unlikely to show findings specific to Myasthenia Gravis, which is a neuromuscular junction disorder.
Myasthenia Gravis Diagnosis
Myasthenia Gravis is an autoimmune disorder characterized by fluctuating muscle weakness that worsens with activity and improves with rest, caused by antibodies attacking acetylcholine receptors at the neuromuscular junction. Diagnosis is primarily confirmed by detecting these specific antibodies.
- Common symptoms: ptosis, diplopia, dysphagia, generalized muscle weakness.
- Weakness is often worse at the end of the day or after exertion.
- Acetylcholine receptor (AChR) antibodies are highly specific for diagnosis.
Memory trick: Myasthenia Makes Muscles Melt with Movement.