Bishop Chapter 23 The Thyroid Gland Flashcards
The thyroid gland is responsible for the production of what two hormones?
Thyroid hormone and calcitonin.
What is the clinical significance of calcitonin?
Secreted by parafollicular C cells and is involved in calcium hemostasis.
The parathyroid glands regulates ___.
Serum calcium levels.
Define hypothyroidism.
The thyroid doesn’t create and release enough thyroid hormone.
Why is the thyroid hormone critical for fetuses?
Can cause fetal neurologic development and hypothyroidism can lead to mental retardation (or cretinism).
Thyroid hormone is made primarily of what trace element?
Iodine.
Thyroid cells are organized into spheres surrounding a central core of fluid called what?
Colloid.
What is the major component of colloid?
Thyroglobulin.
What are the two active forms of thyroid hormone?
Triiodothyronine (T3) and Thyroxine (T4).
What is the clinical significance of the thyroid stimulating hormone (TSH)?
Stimulates the production of two main hormones, T4 and T3.
Which thyroid hormone is more metabolically active?
T3 which is 3 to 8 times more active than T4.
What are the three major binding proteins, in order of significance?
Thyroxine-binding globulin (TBG), thyroxine-binding pre-albumin (TBPA), and albumin.
What happens after T4 crosses the cell membrane?
It gets deiodinated into T3 (the active form).
What occurs with the thyroid hormones with subclinical hypothyroidism?
The TSH is minimally increased while the free T4 stays within normal range.
What occurs with the thyroid hormones with subclinical hyperthyroidism?
The TSH is low while the free T4 is normal.
Thyroglobulin is a protein synthesized and secreted exclusively by what types of cells?
Thyroid follicular cells.
What antibodies can interfere with thyroglobulin results?
Antithyroglobulin autoantibodies.
What is the most common cause of hyperthyroidism is an autoimmune disorder called what?
Graves’ disease.
Define Graves’ Disease.
An autoimmune disorder that results in the overproduction of thyroid hormones (hyperthyroidism).
in Graves’ Disease, antibodies in this condition are directed at which receptor?
TSH receptor (TSHR).
In Graves’ disease, stimulating the TSH receptor leads to what?
Leads to growth of the thyroid gland and production of excessive amounts of thyroid hormone.
With chronic lymphocytic thyroiditis (Hashimoto’s thyroiditis), how do antibodies effect thyroid hormones?
Antibodies lead to decreased thyroid hormone production by destruction of the thyroid gland.
What diagnostic technique is often the first step and most accurate tool in evaluation of thyroid nodules in the absence of hyperthyroidism?
Fine-Needle Aspiration
