Endocrine 2 Flashcards
Ectopic thyroid tissue can be found along the path of the thyroid’s ________ during embryonic development. Where exactly is ectopic thyroid tissue most commonly found?
found along the path of descent during development. Most commonly found at the base of the tongue and is called the lingual thyroid.
The interaction of thyroid hormone with its _____ ______ ______ ______ results in the formation of a hormone-receptor complex that binds to _____ ______ ______ _____ in target genes, regulating their transcription.
Thyroid hormones bind to nuclear thyroid hormone receptors (intracellular), which then go and bind to thyroid hormone response elements that regulate transcription
What is thyrotoxicosis?
A hypermetabolic state caused by elevated levels of T3 and T4 (most commonly from hyperthyroidism)
What are eight clinical manifestations of hyperthyroidism?
- Soft, warm, flushed skin.
- Heat intolerance.
- Sweating.
- Weight loss despite increased appetite.
- GI issues: diarrhea, malabsorption, hypermobility.
- Cardiac issues: palpitations, tachycardia, aggravation of heart disease in elderly –> CHF.
- Neuro: tremors, nervousness, thyroid myopathy.
- Ocular manifestations
What is thyroid myopathy? How common is it?
Proximal muscle weakness as a result of hyperthyroidism. Develops in 50% of pts with hyperthyroidism.
Describe the ocular manifestations associated with hyperthyroidism.
Sympathetic overstimulation results in a wide, staring gaze and lid lag.
What is “thyroid storm?”
An abrupt onset of hyperthyroidism –> acute elevation of catecholamines during stress –> medical emergency due to cardiac issues (arrhythmias, etc). Happens most commonly in people with Graves disease.
How is the diagnosis of hyperthyroidism made clinically?
Clinical features and lab data like TSH levels. TSH levels will be low (negative feedback).
What are the three causes of hypothyroidism?
- Defective thyroid hormone synthesis (goitrous hypothyroidism).
- Inadequate thyroid parenchyma function (thyroiditis).
- Inadequate TSH or TRH from pituitary or hypothalamus, respectively.
What is cretinism? What are its features (6)?
Hypothyroidism at an early age. Common in places where iodine deficiency is endemic. Features are:
- Skeletal system derangements
- CNS derangements incl. mental retardation
- Short stature
- Coarse facial features
- Protruding tongue
- Umbilical hernia
Name the disease:
Generalized apathy and mental sluggishness in adulthood with cold intolerance. Obesity is a common manifestation. Constipation from decreased GI motility. Pericardial effusions common and enlarged heart and heart failure seen in late stage.
Myxedema (hypothyroidism in adulthood)
How is hypothyroidism diagnosed?
MOST SENSITIVE TEST: elevated TSH (no feedback) seen in primary hypothyroidism. Decreased serum T4 is seen regardless of cause.
Chronic lymphocytic thyroiditis is also called _________ disease. It is the most common cause of _________ hypothyroidism in places where iodine levels are sufficient.
also called Hashimoto disease. Most common cause of goitrous hypothyroidism (defective thyroid hormone synthesis)
What is the cause of chronic lymphocytic thyroiditis aka Hashimoto disease? In what population is it most common?
Autoimmune destruction of the thyroid gland. Most prevalent in females (10:1 over males) between 45 and 65 years old.
Lymphocytic thyroiditis aka Hashimoto disease is usually seen in older women but is a major cause of _______ ______ in children.
nonendemic goiter
Describe the pathogenesis of Hashimoto disease.
Breakdown of thyroid self-tolerance –> CD4+ helper cell sensitization –> 3 pathways: 1) differentiation into TH1 cells that activate macrophages and cause thyroid injury, 2) CD8+ killer cell stimulation causes thyroid injury, and 3) B cell activation to plasma cells that make anti-thyroid Abs.
Is there a genetic component to Hashimoto thyroiditis? Is there an environmental component?
Yeah genetic, it occurs often in first-degree relatives.
Yeah environmental - more prevalent in places with greater iodine intake.
Describe the morphological changes seen in Hashimoto disease (6).
- Enlarged thyroid
- Tan colored
- Nodular pattern
- T lymphocyte infiltration with lymphocyte follicles and germinal centers
- Atrophy of thyroid follicles
- Acidophilic metaplasia of follicular epithelial (HURTHLE of oxyphil) cells
In the development of Hashimoto disease, transient ________ with corresponding elevated T3 and T4 levels may precede hypothyroidism.
transient thyrotoxicosis (hypERthyroidism) may occur first
Patients with Hashimoto thyroiditis often have other ________ diseases and are at increased risk for the development of _____ _________ _________.
often have other autoimmune diseases and are at increased risk for development of B-cell non-Hodgkin lymphomas.
Goiterous hypothyroidism is characterized by ________ of the thyroid due to iodine deficiency (NO inflammation) –> increased TSH levels –> thyroid follicular cell hypertrophy.
enlargement
Most patients with thyroid goiters are euthyroid. What does that mean?
It means the thyroid still makes thyroid hormone.
Some goiters are hormonally active, causing _________.
thyrotoxicosis (increased metabolism due to increased thyroid hormones)