MKSAP Quiz: thyroid nodule
Diclofenac linked to increased cardiovascular risks
A 35-year-old woman comes to the office for her annual physical examination. The patient says she feel well. She has no pertinent personal or family medical history and takes no medications.
On physical examination, vital signs are normal. Palpation of the thyroid gland suggests the presence of a nodule. All other findings of the general physical examination are normal.
Laboratory studies show a thyroid-stimulating hormone level of 1.3 µU/mL (1.3 mU/L) and a free thyroxine (T4) level of 1.3 ng/dL (16.8 pmol/L).
An ultrasound of the thyroid gland reveals a normal-sized gland with a 2-cm hypoechoic right midpole nodule.
Which of the following is the most appropriate next step in management?
A. Fine-needle aspiration biopsy of the nodule
B. Measurement of anti-thyroperoxidase and anti-thyroglobulin antibody titers
C. Neck CT with contrast
D. Thyroid scan with technetium
E. Trial of levothyroxine therapy
MKSAP Answer and Critique
The correct answer is A) Fine-needle aspiration biopsy of the nodule. This item is available online to MKSAP 15 subscribers in the Endocrinology and Metabolism section, Item 16.
Fine-needle aspiration biopsy is the most appropriate next step in the evaluation of this patient. Whereas screening for thyroid nodules with ultrasonography is not recommended, ultrasonography is an excellent modality for assessing the thyroid gland when anatomic abnormalities are suspected clinically. Ultrasonography allows identification of nodules, whether palpable or not, and of nodule characteristics, such as echogenicity, vascular pattern, and presence of calcifications. Fine-needle aspiration is the mainstay in the evaluation of such thyroid nodules in euthyroid patients and has an excellent sensitivity and specificity for detecting cancer. Ultrasonography-guided fine-needle aspiration would be preferred in this patient because the nodule was not definitively palpated on examination.
Nodules can harbor malignancy regardless of the presence or absence of autoimmune disease. Therefore, determination of anti-thyroperoxidase antibody and anti-thyroglobulin antibody titers in this patient is unlikely to be helpful.
Ultrasonography is superior to CT in the evaluation of thyroid nodules, except when there is a goiter with substantial substernal extension. This patient has no such goiter. Because the thyroid nodule has been verified on an ultrasound, further imaging is unnecessary before obtaining a tissue sample.
Thyroid scanning has no role in the initial workup of thyroid nodules because both benign and malignant nodules tend to be hypofunctional or “cold” on a thyroid scan. Thyroid scanning may be helpful when the thyroid-stimulating hormone (TSH) level is suppressed (which this patient's is not) to assess for a hyperfunctioning (“hot”) nodule that does not require fine-needle aspiration biopsy. Hyperfunctioning nodules are rarely malignant.
Suppression of the TSH level with levothyroxine has fallen out of favor in the management of benign nodular thyroid disease because most randomized prospective trials have shown no net reduction in nodule size, and concerns are increasing about the adverse effects of iatrogenic thyrotoxicosis. Suppressive therapy is generally now reserved for patients with a cancer diagnosis.
Key Point
- Fine-needle aspiration is the mainstay in evaluation of nontoxic thyroid nodules.