LECTURE 8 Thyroid Function Flashcards
T4 is also called _______ because 80 percent of of T3 comes from T4
Prohormone
What is the process where conversion of t4 to active t3
Monodeiodination
Maintains the plasma t3 concenctration
Type 1:5’-deiodinase
Maintains the local t3 concentrations in the tissue in which it is present
Type 2:5’-deiodinase
What is the product when inner ring of t4 undergoes monodeiodination
Reverse t3
What will form if the inner ring of T4 undergoes monodeionization
3,3’,5’-triiodotyronine
Mjor carrier protein of t3 and t4 in the circulation
Thyroxine-binding globulin
A water soluble hormone that is brought to the target cell via a protein carrier.
Thyroxine or t4
T/F. Both hormones enter the target cells but all t4 that enters is converted into t3
True
T or f. Only the t3 form of the hormones enters the nucleus and binds to nuclear receptor proteins
True
A group of interrelated neuroendocrine and endocrine organs that regulate and control the secretion of thyroid hormone
Hypothalamic-pituitary-thyroid axis
A tripeptide produced in the paraventricular nucleus of the hypothalamus and secreted into the venous system, which drains the pituitary
Thyroid releasing hormone
True or false. Trh attaches to receptor sites in the pituitary, where it causes increased production and secretion of TSH
True
A chief regulator of thyroid hormone synthesis
TSH
Increasing intracellular levels of cAMP has two main actions:
Trophic action
Production and secretion of thyroid hormone by the thyroid cells
What action where it increases the size of follicular cells and its number so that they csn trap mire iodine
Trophic action that is stimulated by the increasing levels of cAMP
What occurs when the rate of the process decreases as the ocncentraiton of the product increases, in this case thyroid hormone.
Negative feedback system
It is the extrinsic direct mechanism
Hyperparathyroidism access
Extrinsic indirect mechanism
Neurologic, metabolic snd pharmacological mechanism
Mechanism within thyroid cells, ensure that adequate amounts of intrathyroid hormones are also produced, and is dependent on the availability and effects of iodine
Intrinsic mechanism
Why does thyroid disease is predominant to females?
Due to effects of estrogen and androgen
T or false. Estrogen decreases TBG
False.
T or false. Androgen decreases TBG
True
Acts as a preformed matrix containing tyrosyl group; also a glycoprotein
Thyroglobulin
How does the MIT and DIT forms
Iodination of tyrosine residues in thyroglobulin
Where does the conversion of t4 to t3 takes place
Peripheral tissues
It is biologically inert and functions as storage sites of circulating hormones
Protein bound hormones
Exert biologically active effects
Free hormones
Determine if it is T3 or T4
- 3,5,3’-Triiodothyronine
- Principal secretory product
- Major fraction of organic iodine in the circulation
- Prohormone
- Increase levels is first abnormality seen in cases of hyperthyroidism
- Increase levles causes inhibition of TSH secretion
- T3
- T4
- T4
- T4
- T3
- T4
Lagging of upper eyelid on downward rotation pf the eye
Von graefe’s sign
It is one of the significant symptom of hyperthyroidism which it icmrease leukocyte imfiltration in the eyelids causing protruding of the eyes
Exophthalmos
What is the cause of protrudinng of the eyes.
Increase leukocyte infiltration
Used to describe state of thyroid that a patient with thyroyoxicosis may experience that requires emergrncy treatment
Thyroid storm
Type of hyperthyroidism that the problem is intrinsic to the thyroid gland itself.
Primary hyperthyroidism
Type of hyperthyroidism wherein the problem is in the pituitary gland
Secondary hyperthyroidism
What are the diseases in the primary hyperthyroidism?
Toxic multinodular goiter
Thyroid carcinoma
Thyroid adenoma
Struma ovarii
T or false. Grave’s disease cannot cross the placenta and does not affect the fetus during pregnancy.
False. Kay it is IgG
Antibody responsible for grave’s disease. It mimics the TSH and causes the thyroid to increase the synthesis and release of t4
Thyroid stimulating immunoglobulin
An antibody responsible for grave’s disease are formerly called
Long acting thyroid stimulator
Has an alpha subunit that is similar to TSH. however it is a weak stimulator but can still cause hyperstimulation of the thyroid
HSG
HSG is secreted by
Choriocarcinoma
True or false. Hyperthroidism: diffuse goiter, pretibial swelling, exophthalmos
True
The problem is intrinsic to the thyroid gland that can cause increase or excess thyroid hormones in the circulation
Primary thyroid disease
Second common cause of hyperthyroidism
Primary thyroid disease
Which is false about primary thyroid disease
A. Involves hypersection of thyroid hormones from one or more nodules within the thyroid gland
B. Autonomous activity of nodules causes supression of pituitary TSH
C. the problem is in the pituitary gland
D. Graves disease
E. Toxic nodular goiter
F. Plummer’s disease
C and D
It is not a single disorder but term used to described a group of inflammatory disease that affect the thyroid gland
Thyroiditis
Uncommon inflammatory disease that result from an infection of the thyroid gland by gram positive microorganism
Acute thyroiditis
What are the microorganism is associated with acute thyroiditis
Staphylococcus aureus, Staphylococcus preumoniae, Staphylococcus pyogenes
Identify disease wherein there is neutrophilic leukocyte, elevated sedimentation rate, normal thyroid function
Acute thyroiditis
What is the confirmatory test for thyroiditis caused by gram positive microorganism
Needle aspiration
Culture revealing a pathogenic organism
Inflammatory disorders that us most likely due to virus
Subacute thyroiditis
T or f. Secondary thyroiditis results from ruptured follicles and leakage of large amounts of stored hormones in to the circulation
False. Subacute thyroiditis
What lab findings that causes thyroiditis due to virus
Elevated serum thyroglobulin
What thyroid disease that is based on the ff. laboratory results.
High sensitive TSH levels and high free t4
Secondary hyperthyroidism
Low sensitive TSH Levels but free t4 and free t3 are normal
Subclinical hyperthyroidism
Low sensitive TSH levels, free t4 normal, high free t3
T3 thyrotoxicosis
Sensitive TSH is greatly suppressed or low but free t4 is high
Primary hyperthyroidism
Positive thyroid antibodies
Grave’s disease
Nagative for thyroid antibodies
Toxic adenoma or multinodular goiter
Develops whenever insufficient amounts of thyroid hormone are available to tissues
Hypothyroidism
Causes of hyperthyroidism where in the problem is in the thyroid gland, presemce of parenchymal disease, therapeutic ablation, thyroid dysgenesis, thyroid imfiltration
Primary thyroid dysfunction
Cause of hypothyroidism that occurs after surgery and 131 therapy
Therapeutic ablation
Causes of hyperthyroidism wherein aplasia and dysplasia is significant
Thyroid dysgenesis
What cause of hypothyroidism wherein there is TSH deficiency
Pituitary hypothyroidism
Deficiency in TRH amd it has problem with hypothalamus
Hypothala,ic hypothyroidism
Syndrome found in patients with severe hypothyroidism
Myxedema
Severe manifestation of long standing hypothyroidism
Myxedema coma
Symptoms result from a genrAl slowing down of metabolic processes
Overt hypothyroidism
Cretenism in infants is caused by
Congenital Hypothyroidism
Screning forcdetection of neonatal hypothyroidism and is also considered as most sensitive for diagnosis
Elevated TSH
Identify if it is hashimoto’s thyroidism or Grave’s disease or both
- 10:1
- Cellular and antibody mediated destruction of thyroid tissue
- Amtibody mimics TSH
- HLA B8
- high TSH
- Low TSH
- Hypo
- hypo
- Hyper
- Both
- Hypo
- Hyper
What specimen is used to detect hypothyroidism in newborn screening
Whole blood
It is usaloy affect young patients especially women, characterized by a firm, solitary nodule that is clearly different from the rest of the gland,
Papillary carcinoma
More invasive than papillary carcinoma, can spread to the lymph nodes of blood vessels with metastases to bone
Follicular carcinoma
Arises from psrafollicular cells of thyroid or c cells and produce excess calcitonin
Medullary carcinoma
This group of tumors includes small cells, giant cells and spindle carcinomas, usually occur in patients with long history of goiter
Undifferentiated thyroid carcinoma
Low TSH, low free t4 and blunt response to TRH stimulation test
Secondary hypothyroidism
Can be used for detection of hyper or hypo thyroidism in patients who are taking drugs
sTSH