01/19/2010
Jon C. White. M.D. J C Whit M D Veterans Affairs Medical Center
Thyroid Physiology T3 ‐ more active hormone when unbound or ‘free ‘
(Cytomel) T4 ‐ larger pool of nonactive or ‘bound’ hormone
((Synthroid) y ) Thyroglubulin –protein site of T3,T4 synthesis –
useful tumor marker TSH – negative feedback from T4 – stimulates both
hormone release and growth of thyroid tissue (nodules and cancer) Calcitonin made by parafollicular ‘C’ cells ‐ medullary cancer tumor marker
Thyroid anatomy 15‐25 grams (goiter is twice that size) Two arteries – superior, inferior Two nerves
‐ superior laryngeal, ext. and int. (close to sup artery) ‐ recurrent laryngeal (close to inferior art) Three veins – superior, middle, and inferior
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Hyperthyroidism Diffuse toxic goiter (Graves disease) – systemic
disease, extrathyroidal disease extrathyroidal manifestations (pretibial myxedema, opthalmopathy, etc.) Single toxic adenoma ‐ local Multiple toxic adenomas ‐ local
Graves Disease Autoimmune disorder, LATS TX 1‐ Anti‐thyroid drugs – PTU, methimazole, beta
blockade – usually transient relief TX2‐ TX Radioactive iodine‐ R di i i di unknown carcinogenic k i i
potential TX3‐Surgery‐ subtotal thyroidectomy‐ risk of surgery,
preop with PTU, methimazole , potassium iodide, beta blocker
Thyroiditis Autoimmune ‐ Hashimoto’s ‐ anti‐microsomal ABs Viral ‐ De Quervains’s Bacterial ‐ Acute suppurative Fibrotic ‐ Riedel’s Treatment varies with symptoms
‐Thyroid replacement when hypothyroid ‐Anti‐thyroid drugs when hyperthyroid ‐Occasional need for surgery for neck compression
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Thyroid Nodules Most are benign and can be followed with serial US
and FNA Rapidly growing or papillary, follicular, or Hurthe cell
neoplasia on FNA should be removed Lobectomy or subtotal thyroidectomy 20% are malignant and will then need total
thyroidectomy
Thyroid Cancer DIFFERENTIATED
‐Papillary ‐Follicular ‐Hurthle Hurthle cell ‐Medullary UNDIFFERENTIATED ‐Anaplastic ‐Small, Spindle, Giant cell ‐lymphoma ‐metastatic
Papillary Cancer Most common (85%), best prognosis Can be multi‐centric (7%) Lymphatic > hematogenous spread Stimulated by TSH Psammoma bodies on histology Surgery
‐lobe and isthmus (less than 1.5 cm) ‐total with central nodes (greater than 1.5) ‐neck dissection for lateral nodes
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Follicular Neoplasm 10 % thyroid cancers Not as favorable as papillary Hematogenous > lymphatic spread H t l h ti d More radio‐responsive Stimulated by TSH Follicular adenoma – lobectomy Follicular cancer – total thyroidectomy
Hurthle Cell Neoplasm Similar to follicular in prognosis Not radio‐responsive Adenoma ‐ lobectomy Cancer ‐ total thyroidectomy
Medullary Cancer 80% sporadic, 20% MEN II Parafollicular ‘C ‘ cells Total thyroidectomy l h d with central node and sometimes h l d d
MRN dissection Calcitonin is tumor marker Worse prognosis of differentiated tumors
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Adjuvant Treatment Radioactive iodine I‐131(diagnostic and therapeutic)
pp y Suppressive thyroid hormone Follow tumor markers
‐Pap. and follic. ‐ thyroglobulin ‐Medullary ‐ calcitonin Chemo and radiation for undifferentiated
Prognosis AGES, AMES, MACIS, etc. Extremes of age have worse prognosis Grade (extent of invasion) Size Presence of mets Completeness of resection
Parathyroid glands 3‐7 glands (25‐50 mg each) Calcium metabolism Superior from fourth pharyngeal pouch Inferior from third pouch Blood supply from superior and inferior thyroid
arteries Location, location, location
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Hyperparathyroidism Primary – 80% adenoma , 20% hyperplasia, 1% CA Secondary – 90‐100% hyperplasia Stones, bones, and abdominal groans (+muscle pain) Dx’d by elevated serum CA and PTH Localized by US, nuclear scan (sestamibi), CT, MRI,
angiography, venous sampling
Parathyroidectomy Excise adenoma (unilateral or bilateral approach) Hyperplasia –excise 3 1/2 or all (w/ implant) Three nl glands and no pathology ‐ pull up thymus,
possible thyroid lobectomy, do not open sternum at first operation Hungry bone syndrome – severe hypocalcemia after removing hyperplastic glands
Multiple Endocrine Neoplasia MEN
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‐ Parathyroid hyperplasia, pancreatic islet cell p y tumor, pituitary adenoma
MEN
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– Parathyroid hyperplasia, medullary CA of thyroid, pheochromocytoma
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MEN 1 ‐ Treatment 3 1/2 gland or total parathyroidectomy (w/implant) Medical control or excision of pancreatic tumor if M di l l i i f i if
possible (gastrinoma or insulinoma) Pituitary resection or irradiation as needed
MEN 2 ‐ Treatment W/up with serum and urinary catecholamines Alpha then beta blockade Unilateral or bilateral adrenalectomy 3 ½ gland or total (w/implant) parathyroidectomy Total thyroidectomy w/ appropriate LN dissection
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