Pathology of the Thyroid Flashcards
Where does the thyroid gland develop?
- at the base of the tongue and travels along the thyroglossal duct to the anterior neck.
What is a thyroglossal duct cyst?
- cystic dilation of the thyroglossal duct remnant.
- presents as an anterior neck mass.
What is a lingual thyroid?
- persistence of thyroid tissue at the base of the tongue.
- presents as a mass at the base of the tongue.
What is HYPERthyroidism?
- increased level of circulating thyroid hormone.
- increases BMR
- increases sympathetic nervous system activity.
** How does hyperthyroidism increase BMR?
- by increasing the Na+/K+ ATPase
** How does hyperthyroidism increase the sympathetic nervous system?
- by increasing B1-adrenergic receptors.
What are the clinical features of HYPERthyroidism?
- WEIGHT LOSS despite increased appetite.
- HEAT intolerance and sweating
- tachycardia with increased cardiac output.
- arrhythmia (a-fib) in elderly
- tremor, anxiety, insomnia, and heightened emotions.
- staring gaze with lid lag.
- diarrhea with malabsorption.
- oligomenorrhea
- bone resorption with hypercalcemia.
- decreased muscle mass with weakness.
- HYPOCHOLESTEROLEMIA
- HYPERGLYCEMIA
Why does hyperthyroidism cause HYPOcholesterolemia and HYPERglycemia?
- bc thyroid hormone causes both gluconeogenesis and glycogenolysis
What is the most common cause of hyperthyroidism?
- Graves disease
*** What is Graves disease?
- autoantibody (IgG) stimulates TSH receptor, leading to increased synthesis and release of thyroid hormone.
In what group of people does Graves disease most often occur?
- women of childbearing age
What are the clinical features of Graves disease?
- hyperthyroidism
- diffuse goiter (due to massive hypertrophy and hyperplasia of the thyroid gland).
- EXOPHTHALMOS and PRETIBIAL MYXEDEMA
** What causes exophthalmos and pretibial myxedema in Graves disease?
- fibroblasts behind the eye and behind the shin have TSH receptors, and in response to the autoantibody to the TSH receptor will secrete excess glycosaminoglycans (pushing the eyes outward and giving the shins a dough like appearance and structure).
** What will you see on histology of the thyroid in Graves disease?
- enlarged follicles with SCALLOPING of the colloid (looks white around the edges)
What labs will you see with Graves disease?
- increased total and free T4
- decreased TSH due to the increased T4 down-regulating TRH receptors in the anterior pituitary.
- hypocholesterolemia
- hyperglycemia