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Transition from cold to hot thyroid nodules
S Tumino1, C Fornito, A Laudani
1Istituto di Medicina Interna e Specialità Internistiche, Cattedra di Endocrinologia, Ospedale Garibaldi, University of Catania, Italy.
Thyroid : Official Journal of the American Thyroid Association
|February 12, 1998
Summary
Autonomously functioning thyroid nodules (AFTNs) can initially appear hypofunctioning on radioactive iodine scans. Later re-evaluation revealed these "cold" nodules were indeed AFTNs, challenging initial diagnoses.
Area of Science:
- Endocrinology
- Nuclear Medicine
Background:
- Autonomously functioning thyroid nodules (AFTNs) are a common cause of hyperthyroidism.
- Diagnosis typically involves radioactive iodine (131I) scintigraphy to assess thyroid nodule function.
Observation:
- Three cases of AFTNs initially presented as hypofunctioning ('cold') nodules on 131I scans.
- Patients had normal thyroid hormones and TSH levels at initial observation.
- Initial misclassification led to levothyroxine (LT4) treatment.
Findings:
- Delayed diagnosis of AFTN occurred years later upon repeat thyroid scintigraphy.
- Two patients developed levothyroxine intolerance, prompting re-evaluation.
- Hemorrhagic or cystic degeneration may explain initial hypofunctioning appearance, with subsequent proliferation leading to functional recurrence.
Implications:
- This highlights the potential for misinterpreting initial scintigraphy findings in AFTNs.
- Careful long-term follow-up is crucial for nodules with atypical presentations.
- Understanding nodular degeneration and regeneration is important for accurate thyroid nodule management.