"NONTOXIC GOITERS" & THYROID NODULES


Defined as: Goiters (enlargement of thyroid) which don't produce toxic levels of thyroid hormones

I. Classification

  1. Diffuse
    1. Us. result from insufficient production of thyroid hormones which result in increased TSH secretion and thyroid enlargement
    2. Can result from iodide deficiency, defects in hormone synthesis, exogenous "goitrogens," or thyroiditis
  2. Nodular
    1. Usually evaluated with ultrasound, fine-needle aspiration, and radioiodine scan, in which a picture of regional iodine uptake in the thyroid is obtained
    2. Nodules that take up lots of iodine are presumed to have retained thyroid-like function and are referred to as "hot," and those that don't, "cold"
    3. Cold nodules tend to contain less-well differentiated tissue and are more likely to become cancerous (10-15% probability) and should be sampled at least with fine needle aspiration; treating with thyroxine may reduce development of new cold nodules but doesn't seem to shrink size of existing nodules (J. Clin. Endocr. Metab. 83:780, 1998--JW); can also tx cold nodules with percutaneous injection of ethanol; can also leave them alone if cytology is negative!
    4. Risk factors for malignancy in a solitary thyroid nodule:
      1. Male gender
      2. Age < 30yo or > 60yo
      3. Rapid growth of nodule or size > 4cm
      4. Cervical lymphadenopathy
      5. Symptoms of local invasion (dysphagia, hoarse voice, neck pain)
      6. History of radiation therapy to thyroid
      7. Family history of thyroid Ca

II. Treatment options

  1. Surgery
  2. Thyroxine (reduces size by reducing TSH levels)
  3. Radioiodine (the latter ass'd with sig. greater size reduction and less bone density reduction than thyroxine in a randomized trial of 64 pts--J. Clin. Endocrin. Metab. 86:994, 2001--JW)