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Difficulty: EasyDiagnostic Workup and Test Sequencing

An otherwise healthy 45-year-old female teacher establishes care at a new primary care office. She reports feeling well with no recent changes in weight, bowel habits, temperature tolerance, or energy levels. Vital signs are within normal limits. During the physical examination, the physician palpates a 1.5-cm, firm, mobile, non-tender nodule in the right lobe of the thyroid gland. There is no palpable cervical lymphadenopathy, and the remainder of the examination is unremarkable. Which of the following is the most appropriate next step in the diagnostic workup?

  1. Measurement of serum thyroid-stimulating hormone and thyroid ultrasonographyAnswer
  2. B
    Fine-needle aspiration biopsy of the thyroid nodule
  3. C
    Radionuclide thyroid scanning
  4. D
    Computed tomography of the soft tissues of the neck
  5. E
    Clinical observation with repeat palpation in six months

Answer

The most appropriate initial diagnostic step is to measure the serum thyroid-stimulating hormone (TSH) level and perform a thyroid ultrasound.
The correct answer accurately reflects current consensus guidelines for the evaluation of a thyroid nodule. A serum TSH level determines whether the nodule is hyperfunctioning (which typically correlates with a much lower risk of malignancy), while an ultrasound provides detailed anatomical information, confirms the nodule's presence, measures its exact size, and identifies suspicious sonographic features (such as microcalcifications, solid composition, or irregular margins) that would dictate the need for a biopsy.

Step-by-Step Solution

1
Identify the primary clinical problem presented in the vignette.
The patient has a newly discovered, asymptomatic, palpable 1.5-cm thyroid nodule.
Establishing the central problem dictates which clinical pathway or guideline to apply.
2
Determine the goals of the initial evaluation for this condition.
The evaluation must determine the functional status of the nodule (is it producing excess hormone?) and its risk for malignancy (does it have suspicious structural features?).
Thyroid nodules are very common, but a small percentage are malignant. The workup must efficiently risk-stratify the patient.
3
Select the guideline-concordant tests that achieve these goals safely and cost-effectively.
Serum TSH provides the biochemical functional status, while ultrasound provides the precise size and anatomic characteristics.
These two tests form the foundation of the workup algorithm, dictating whether further interventions like fine-needle aspiration or radionuclide scanning are required.

Key Concept

The initial diagnostic workup for all newly discovered palpable thyroid nodules involves biochemical evaluation with a serum TSH level and anatomic evaluation with thyroid ultrasonography.
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Diagnostic Workup and Test Sequencing

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