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Difficulty: EasyEndocrinology and Metabolism

A 45-year-old woman is found to have a palpable 2.5-cm nodule in the right lobe of her thyroid gland during a routine physical examination. Arrange the following steps in the correct chronological sequence for the standard diagnostic evaluation and management of this patient. Assume that her initial biochemical testing reveals a suppressed TSH level and subsequent imaging demonstrates a non-functioning nodule.

  1. 1Measure serum thyroid-stimulating hormone (TSH) level and perform a neck ultrasound.
  2. 2Perform a radionuclide thyroid scan to evaluate for autonomous function.
  3. 3Perform a fine-needle aspiration (FNA) biopsy of the nodule.
  4. 4Determine the need for surgical resection versus clinical surveillance.

Answer

The correct chronological sequence is to first measure TSH and perform a thyroid ultrasound, followed by a radionuclide thyroid scan (due to the suppressed TSH), then a fine-needle aspiration (FNA) biopsy (due to the non-functioning nature of the nodule), and finally determine surgical versus surveillance management based on cytology.
The standard evaluation of a thyroid nodule strictly begins with a serum TSH and ultrasound. If the TSH is low, a radionuclide scan is required to check for autonomous function. A 'hot' nodule is treated for hyperthyroidism, while a 'cold' nodule requires an FNA biopsy due to malignancy risk. Finally, the FNA cytology results guide definitive management.

Step-by-Step Solution

1
Identify the standard initial evaluation for a newly discovered palpable thyroid nodule.
TSH measurement and a thyroid ultrasound are always the first steps in the algorithm.
TSH determines if the nodule might be hyperfunctioning, while ultrasound assesses the size and identifies suspicious sonographic features.
2
Determine the next indicated step for a patient presenting with a suppressed (low) TSH.
A radionuclide thyroid scan is indicated.
A low TSH suggests hyperthyroidism. The radionuclide scan differentiates between a 'hot' (hyperfunctioning) nodule, which is rarely malignant, and a 'cold' (non-functioning) nodule.
3
Determine the appropriate diagnostic procedure for a 'cold' nodule.
Fine-needle aspiration (FNA) biopsy is performed.
Non-functioning ('cold') nodules have an increased risk of malignancy and require direct cytological evaluation to rule out thyroid cancer.
4
Establish the final step in the clinical pathway.
Definitive management is chosen based on FNA cytology.
The cytological results (e.g., benign, malignant, indeterminate) dictate whether the patient undergoes surgical resection or routine ultrasonographic observation.

Key Concept

The diagnostic algorithm for a palpable thyroid nodule depends primarily on the initial serum TSH level; a low TSH warrants a radionuclide scan, and subsequent 'cold' nodules require FNA biopsy.
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Topics

Endocrinology and Metabolism

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