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Zorluk: OrtaDiagnostic Workup and Test Sequencing

A 48-year-old woman presents to her primary care physician for a routine health maintenance examination. She reports feeling generally well but mentions experiencing occasional episodes of a racing heartbeat over the past two months. She has no significant past medical history and takes no medications. Vital signs show a blood pressure of 130/80 mm Hg, heart rate of 98/min, and respiratory rate of 14/min. Physical examination reveals a palpable, mobile, non-tender mass in the right anterior neck. No cervical lymphadenopathy is appreciated. A targeted ultrasound of the neck demonstrates a 2.4-cm solid, isoechoic nodule in the right lobe of the thyroid gland with no microcalcifications. Laboratory studies are ordered, which reveal a serum thyroid-stimulating hormone (TSH) level of 0.08 mU/L (normal: 0.4-4.0 mU/L) and a free thyroxine (T4) level of 2.2 ng/dL (normal: 0.9-1.7 ng/dL). Which of the following is the most appropriate next step in the diagnostic workup of this patient?

  1. A
    Fine-needle aspiration biopsy
  2. B
    Contrast-enhanced computed tomography of the neck
  3. Radionuclide thyroid scintigraphyCevap
  4. D
    Measurement of serum thyroglobulin concentration
  5. E
    Reassurance and repeat ultrasonography in 6 months

Cevap

Radionuclide thyroid scintigraphy
The most appropriate next step in the diagnostic workup for a patient with a thyroid nodule and a concomitantly suppressed TSH is radionuclide thyroid scintigraphy (e.g., Iodine-123 or Technetium-99m scan). This step determines if the nodule is hyperfunctioning ('hot') or non-functioning ('cold'). Hyperfunctioning nodules are rarely malignant and generally do not require fine-needle aspiration (FNA). If the scan shows the nodule is 'cold', an FNA would then be indicated based on ultrasound characteristics.

Adım Adım Çözüm

1
Evaluate the clinical and laboratory presentation.
The patient has a palpable 2.4-cm thyroid nodule accompanied by a suppressed TSH and elevated free T4.
Identifying the initial clinical data dictates the algorithm for evaluating a thyroid nodule.
2
Determine the proper diagnostic pathway based on the TSH level.
Because the TSH is below normal (suppressed), the functional status of the nodule must be evaluated before considering any invasive testing.
Hyperfunctioning nodules (which cause a suppressed TSH) are extremely rarely malignant and therefore do not typically require biopsy.
3
Select the appropriate test to assess nodule function.
A radionuclide thyroid scan is selected.
Scintigraphy will differentiate a 'hot' nodule (e.g., toxic adenoma) from a 'cold' nodule (which would require a biopsy).

Anahtar Kavram

The initial evaluation of a newly discovered thyroid nodule requires concurrent TSH measurement and ultrasound. If the TSH is suppressed, radionuclide scintigraphy is the mandatory next step to assess whether the nodule is hyperfunctioning.
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Konular

Diagnostic Workup and Test Sequencing

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