Thyroid Nodules in Primary Care: What to Do Next

A thyroid nodule is a rounded growth within the thyroid gland. Most adult nodules are benign, but evaluation matters because a small percentage are malignant.

Who Gets Them (and why that matters)

• Children: Nodules are less common but more likely malignant → early endocrine/surgical referral.

• Adults: Most nodules are benign (multinodular goiter, colloid nodules, cysts).

• Concerning clinical features: fixed, firm, non-tender nodule; rapid growth; hoarseness, dysphagia, dyspnea; cervical lymphadenopathy; prior head/neck radiation; strong family history of thyroid cancer.

Thyroid dysfunction symptoms (hyper/hypo) don’t rule cancer in or out—nodules often occur with normal thyroid function.

First-Line Workup (Day 1 in clinic)

1. TSH

   • Low TSH → consider radionuclide uptake/scan (hyperfunctioning “hot” nodules are rarely malignant; FNA usually not indicated).

   • Normal or high TSH → proceed with ultrasound risk stratification.

2. Dedicated Thyroid Ultrasound
   Ask radiology to apply TI-RADS (ACR) or ATA pattern-based risk stratification and to document:

   • Composition (solid, cystic, mixed)

   • Echogenicity (hypoechoic, isoechoic, etc.)

   • Margins (smooth vs. irregular)

   • Taller-than-wide shape

   • Microcalcifications

   • Size in three dimensions

   • Cervical lymph nodes

Ultrasound features that raise suspicion: solid hypoechoic, irregular/lobulated margins, microcalcifications, taller-than-wide, extrathyroidal extension, suspicious nodes.

When to Biopsy (FNA), Simplified

(Thresholds vary by system—follow your local radiology/ATA/ACR guidance. A simple ATA-style snapshot:)

• High-suspicion pattern → FNA ≥1.0 cm

• Intermediate-suspicion → FNA ≥1.0 cm

• Low-suspicion → FNA ≥1.5 cm

• Very-low suspicion / spongiform → Consider FNA ≥2.0 cm or observe

• Purely cystic → No FNA

If TSH is low and uptake scan shows a hot nodule: FNA is usually not needed.

Management & Follow-Up

• Benign cytology (Bethesda II):

  • Annual: TSH, targeted neck exam; US at ~12–24 months (then extend interval if stable).

  • Re-biopsy if growth (>20% increase in ≥2 dimensions with minimal increase ≥2 mm, or >50% volume) or new suspicious features.

• Indeterminate cytology (Bethesda III/IV):

  • Discuss molecular testing and/or endocrine/surgical referral.

• Suspicious or malignant cytology (Bethesda V/VI):

  • Refer to endocrine and surgery for definitive management.

• Compressive symptoms (dysphagia, dyspnea, voice change) or cosmetic concerns with benign nodules:

  • Refer to endocrine and surgery, they will consider surgical options or nonsurgical (e.g., ethanol or radiofrequency ablation—per local availability). 

Special Notes

• Biotin supplements can distort thyroid labs (falsely low TSH, high T4/T3). Ask patients to hold biotin for 48 hours before testing.

• Pregnancy: Avoid radionuclide scanning; coordinate with endocrinology.

• Children/adolescents: Lower biopsy threshold and early specialty referral.

Patient Counseling (quick script)

• “Most nodules are benign. We’ll check hormone levels and get a high-quality ultrasound. If the ultrasound meets certain criteria, we’ll do a small needle biopsy. If the biopsy is benign, we’ll monitor it over time.”

• “Call urgently for voice changes, trouble swallowing/breathing, or rapid growth.”

Education only; use your clinical judgment and local protocols.

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