Thyroid Gland Flashcards
What is the functional unit of the thyroid?
Follicle (acini)
What are follicles filled with?
Thyroglobulin
What two types of cells are contained w/i the thyroid?
Follicular cells and parafollicular (C) cells
What is secreted by the C cells?
Calcitonin
Which of the thyroid hormones is the precursor and which is the active?
T4 and T3 respectively
What is thyroid agenesis?
Complete absence of the thyroid tissue
What is a goiter?
Thyroid enlargement
What is nontoxic goiter?
Thyroid enlargement without functional, inflammatory or neoplastic alterations
What type of goiter is thought to have genetic etiology?
Simple nodular thyroid enlargement
What is the early stage of nontoxic goiter?
Diffuse nontoxic goiter
What does multinodular nontoxic goiter reflect?
More chronic disease
What are the blood concentrations of thyroid hormone in a patient with nontoxic goiter?
T3 and T4 are normal! (Euthyroid)
What type of goiter causes hyperthyroidism?
Toxic goiter
What is hypothyroidism?
Clinical manifestation of thyroid hormone deficiency
What are the three main causes of hypothyroidism?
Defective thyroid hormone synthesis, Inadequate thyroid fn., Inadequate secretion of TSH by the pituitary/TRH by the hypothalamus
What are often the first Syx of hypothyroidism?
Fatigue, lethargy, sensitivity to cold, and inability to concentrate
What is the peculiar type of edema that occurs in patients w/ hypothyroidism?
Myxedema
What is the name of the severe agitation seen in hypothyroid patients?
Myxedema madness
What is the major effect on the heart caused by hypothyroidism?
Myxedema heart (dilated heart and pericardial effusion)
How does hypothyroid affect the bowels?
Decreased peristalsis can lead to constipation, fecal impaction and myxedema megacolon
What is primary hypothyroidism often a manifestation of?
Autoimmune disease
What is goitrous hypothyroidism?
Thyroid enlargement associated with hypothyroidism
What is endemic goiter?
Goitrous hypothryoidism due to dietary iodine deficiency
What is a commonly used bipolar medicine that is antithyroid and goitrogenic?
Lithium
What does excess iodide intake cause?
Iodide induced goiter
What is another term for congenital hypothyroidism?
Cretinism
What are the two overlapping clinical presentations of endemic cretinism?
Neurologic and hypothyroid cretinism
What is neurologic cretinism?
Features mental retardation, ataxia, spasticity, and deaf-mutism
What is believed to be the cause of congenital hypothyroid cretinism?
Iodine deficiency in late fetal life and neonatal period
What is hyperthyroidism?
Clinical consequence of excessive circulating thyroid hormone