Nontoxic Goiter Workup

Updated: Dec 12, 2016
  • Author: Stephanie L Lee, MD, PhD; Chief Editor: George T Griffing, MD  more...
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Workup

Laboratory Studies

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  • Assess all patients with goiter for thyroid dysfunction with a serum thyrotropin (TSH) assay. Second-generation or better TSH assays can detect clinically inapparent (subclinical) hyperthyroidism and hypothyroidism.

    • If the TSH is high, consider chronic autoimmune thyroiditis (Hashimoto thyroiditis) or ingestion of a goitrogen, such as lithium or amiodarone, as well as dyshormonogenesis in a child. Correction of the hypothyroid status by withdrawal of the goitrogen or institution of thyroid hormone replacement therapy may greatly reduce the size of the goiter.

    • If the TSH is low, measurement of serum free thyroxine (free T4) or free T4 index and total triiodothyronine (T3) is used to confirm the diagnosis of thyrotoxicosis. After many years, a nontoxic goiter may develop areas of functional autonomy (as seen in the image below) and thyrotoxicosis. Treatment of thyrotoxicosis includes stabilization of the hyperthyroid state with antithyroid medications and then surgical removal of the goiter or the administration of radioactive iodine ablative therapy.

      Areas of autonomy with excess thyroid hormone secr Areas of autonomy with excess thyroid hormone secretion in a large nodular goiter. This technetium-99m (99mTc) thyroid scan shows hot and cold nodules in a multinodular goiter. Although the patient's thyroid-stimulating hormone level had become progressively suppressed, it was within the reference range, at 0.4 mU/mL (reference range 0.35-5.5 mU/mL).
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Imaging Studies

Assessment of size and extent of the goiter is necessary to determine if progressive growth of the thyroid is occurring. Clinical assessment by an experienced clinician is often accurate until the thyroid increases to 4-5 times the normal size.

Measurement of neck circumference is a crude measure of thyroid size. Ultrasonography is good for estimating the number, size, and sonographic characteristics of nodules but is inaccurate in the clinical setting for measuring the volume of large goiters. Suspicious ultrasound characteristics, including hypoechogenicity, microcalcifications, macrocalcifications, intranodular vascularity, taller-than-wide dimensions, and blurred margins, guide the clinician as to which nodule requires biopsy for malignancy. [2, 1] Computed tomography (CT) scanning and magnetic resonance imaging (MRI), although expensive, are excellent for assessing tracheal compression and intrathoracic extension of the goiter.

A barium swallow may be used to document esophageal obstruction in patients with significant symptoms of dysphagia.

Thyroid scintigraphy is not routinely indicated in the assessment of goiter size unless a concern of thyroid hemiagenesis exists or the TSH is suppressed consistent with hyperthyroidism. A nodule with equivocal findings on thin-needle aspiration may be further evaluated using thyroid scintigraphy. A hot area supports the presence of a benign lesion. Examples of technetium-99m (99m Tc) thyroid scans are shown below. [2, 1]

Technetium-99m (99mTc) thyroid scan of a large, no Technetium-99m (99mTc) thyroid scan of a large, nontoxic multinodular goiter. Multiple cold and hot nodules are observed in the enlarged thyroid gland. The white arrow indicates sternal notch marker.
Areas of autonomy with excess thyroid hormone secr Areas of autonomy with excess thyroid hormone secretion in a large nodular goiter. This technetium-99m (99mTc) thyroid scan shows hot and cold nodules in a multinodular goiter. Although the patient's thyroid-stimulating hormone level had become progressively suppressed, it was within the reference range, at 0.4 mU/mL (reference range 0.35-5.5 mU/mL).
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Other Tests

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  • Pulmonary function tests may be used as a functional assessment of tracheal compression. Characteristic changes of external tracheal compression can be detected in flow-volume loop tracings in asymptomatic patients with goiter. Direct laryngoscopy can, as indicated in the image below, also demonstrate tracheal compression.

    Relief of tracheal compression after subtotal thyr Relief of tracheal compression after subtotal thyroidectomy of large, obstructive, nontoxic multinodular goiter. (A) Laryngoscopy demonstrating critical tracheal narrowing before thyroidectomy; (B) laryngoscopy showing widened patent trachea after thyroidectomy.
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Procedures

A subset of patients presenting with goiter who do not have hyperthyroidism or has a cold nodule on nuclear thyroid scan with hyperthyroidism should have a fine-needle aspiration biopsy as the first diagnostic procedure. Clinical indication for biopsy includes suspicious sonographic characteristics listed above, asymmetrical and/or rapid growth of a nodule or lobe of a thyroid gland or unilateral adenopathy. Generally, in patients with the usual nonnodular nontoxic goiter that is long-standing with slow growth, fine-needle biopsy is not necessary unless sonographically suspicious nodules are present. [2, 1]

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Histologic Findings

A variety of features may be observed with fine-needle aspiration cytology of a multinodular goiter. [4] This variation is mostly explained by different stages of nodule formation. A proliferative phase exists in which the sample may contain many follicular cells. This can sometimes be difficult to distinguish from a follicular adenoma versus a follicular carcinoma. Colloid is another prominent feature. It represents the stored thyroid hormone within the follicle. Its absence suggests a more worrisome diagnosis.

After proliferation of follicular cells, a hemorrhage may occur inside the nodule. Erythrocytes and foamy macrophages that have ingested colloid material may be observed. Another potential area of concern is an aspiration that only returns cyst contents, ie, erythrocytes and macrophages without follicular cells. This cannot be used to definitively rule out the presence of thyroid cancer, and a reaspiration should be performed.

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