Thyroid Pathology Flashcards
What is the essential action of thyroid hormones?
Increase in basal metabolic rate
What effect does T3 have on the liver?
Increased cholesterol synthesis, cholesterol reabsorption from plasma, conversion of cholesterol to bile acids, fat oxidation/synthesis and gluconeogenesis
What effect does T3 have on the adipose?
Increase FA mobilization
What effect does T3 have on the heart?
Increase HR and hypertrophy
What effect does T3 have on the pituitary gland?
Decreases TSH production and increases GH
What effect does T3 have on the skeletal M?
Increases protein catabolism, glucose utilization and fat oxidation
What effect does T3 have on bone?
Increased growth, maturation and resorption
What is synthesized and stored in colloid?
Thyroglobulin (Tg)
What can cause secondary hyperthyroidism?
Pituitary adenoma (secreting TSH)
What are the lab values associated with primary hyperthyroidism?
Low TSH and elevated T3/4
What are the lab values associated with secondary hyperthyroidism?
Elevated TSH and T3/4
What are some causes of primary hypothyroidism?
Genetic defects in thyroid development, thyroid hormone resistance syndrome, postablative (surgery, radioiodine therapy, irradiation), autoimmune hypothyroidism, iodide deficiency, drugs (lithium, iodides, p-aminosalicylic acid), congenital biosynthetic defect
What are some causes of secondary hypothyroidism?
Pituitary or hypothalamic failure
What are the signs and sx associated with hypothyroidism in the adult/older child (myxedema)?
Dry brittle hair, hair loss, edema of face and eyelids, cold intolerance, diminished perspiration, coarse, cool, dry yellowish skin, lethargy, memory impairment, slow cerebration, thick tongue, slow speech, deep coarse voice, enlarged heart, poor heart sounds, diastolic HTN
What can radioisotope scanning determine?
If a specific nodule is responsible for hyper function; if so, it can be treated with excision or ablation (hot nodules)
Cold nodules are more likely to be what?
Neoplastic, but US and FNA are more useful in that workup
FNA can be used to determine what?
Cellular constituents of a nodule
What is the clinical management when there is insufficient information for a dx after FNA of a cold nodule?
Repeat FNA
What is the clinical management for benign cytology of a cold nodule?
Clinical discretion (follow)
What is the clinical management for AUS cytology of a cold nodule?
Repeat FNA
What is the clinical management for cytology that is suspicious for follicular or Hurthle cell neoplasm?
Hemithyroidectomy
What is the clinical management for cytology of a cold nodule that is suspicious for malignancy?
Hemithyroidectomy or near total thyroidectomy
What is the clinical management for malignant cytology of a cold nodule?
Near total thyroidectomy +/- central LN dissection
What are the treatment options for differentiated thyroid carcinoma?
Surgery or radioactive iodine (I^131); chemotherapy if refractory
What is the function of C cells?
Responsible for calcitonin secretion
