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Zorluk: ZorOrdering Laboratory Tests

Match each of the following patient clinical vignettes with the most appropriate, highly specific diagnostic laboratory test required to confirm the underlying etiology.

  • A 27-year-old woman is brought to the emergency department presenting with acute-onset psychosis, autonomic instability, prominent orofacial dyskinesias, and a 6-centimeter solid and cystic right adnexal mass on pelvic ultrasound.Cerebrospinal fluid assay for anti-N-methyl-D-aspartate (NMDA) receptor antibodies
  • A 62-year-old man with a 40-pack-year smoking history reports progressive difficulty rising from a chair. Examination reveals absent patellar reflexes that become briskly normal immediately following 10 seconds of maximal voluntary isometric contraction.Serum assay for voltage-gated calcium channel (VGCC) antibodies
  • A 45-year-old woman presents with intermittent diplopia and difficulty chewing that consistently worsens during prolonged meals. Examination shows asymmetric ptosis exacerbated by sustained upward gaze, and chest imaging reveals an anterior mediastinal mass.Serum assay for acetylcholine receptor (AChR) binding, blocking, and modulating antibodies
  • A 68-year-old man presents with a 5-week history of rapidly progressive memory loss, spatial disorientation, and sudden, shock-like involuntary arm movements when startled. Electroencephalography demonstrates generalized periodic synchronous sharp wave complexes.Cerebrospinal fluid real-time quaking-induced conversion (RT-QuIC) assay

Cevap

The correct matches pair the young woman with a teratoma to CSF anti-NMDA receptor antibodies; the older smoker with improving reflexes to Serum VGCC antibodies; the woman with fatigable weakness and a mediastinal mass to Serum AChR antibodies; and the elderly man with rapid dementia and myoclonus to the CSF RT-QuIC assay.
Each clinical vignette provides classic epidemiological and physical exam clues pointing to a specific neurological pathology that requires a distinct, targeted laboratory test for confirmation. Identifying the precise autoantibody or abnormal protein is required to establish the definitive diagnosis and guide subsequent therapy or malignancy screening.

Adım Adım Çözüm

1
Analyze the first vignette to identify the underlying syndrome.
The combination of new-onset psychosis, dyskinesias, autonomic instability, and an adnexal mass (likely a teratoma) indicates anti-NMDA receptor encephalitis.
Ovarian teratomas commonly contain neural tissue that can trigger an autoimmune response against NMDA receptors.
2
Differentiate between the neuromuscular junction disorders in the second and third vignettes.
The second vignette demonstrates post-tetanic potentiation (reflexes improving with use), characteristic of Lambert-Eaton myasthenic syndrome (VGCC antibodies). The third vignette demonstrates fatigability (worsening with use) and a thymoma, characteristic of myasthenia gravis (AChR antibodies).
Distinguishing between presynaptic (VGCC) and postsynaptic (AChR) neuromuscular junction defects is critical for ordering the correct diagnostic antibody panel.
3
Identify the rapidly progressive neurodegenerative disease in the fourth vignette.
Rapid dementia, myoclonus, and periodic EEG sharp waves point to Creutzfeldt-Jakob disease (CJD), which is confirmed via CSF RT-QuIC.
RT-QuIC has largely replaced 14-3-3 protein testing alone due to its superior diagnostic specificity for prion disease.

Anahtar Kavram

Selection of targeted immunologic and specific protein assays for the diagnosis of paraneoplastic, autoimmune, and rapidly progressive neurological diseases.
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Ordering Laboratory Tests

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