Thyroid ENT

A daily dietary intake of at least ________ug of iodine per day is required

100

Pts with + AMA and elevated TSH even with normal serum T4 levels have a

3-5% per year likelihood of clinical hypothyroidism

Antimicrosomal antibodies (AMA) aka anti-TPO detected in more than

90% of patient with chronic autoimmune thyroid disease.

Circulating ____ accounts for most of the physiologic activity of the thyroid hormone

Circulating T3

Elevated T4 levels may occur when there is a production of endogenous antibodies to T4 especially with:

Hashimotos thyroiditis Waldenstrom macroglobulinemia

Type I deiodinase is the primary source of circulating T3 and is found in tissues of the liver, kidney and thyroid, where it is activated by TSH. It is inhibited by what anithyroid drug

PTU: Propylthiouracil

Acute/subacute thyroidits tx

Salicylates or NSAIDs, if resistant trial of prednisone

MIT: monoiodotyrosine and DIT diiodotyrosine combine to form ______ or 2 of DIT to form

T3 T4

withdraw of iodide from the diet leads to rapid decrease in serum T____ with serum T____ levels being unaffected. With prolonged iodine deficiency, TSH stimulated cell proliferation leads to a goiter

T4 with T3

What thyroid hormone is released from the hypothalamus

Thyrotropin-releasing hormone

What are the 2 hormones produced by the thyroid gland that are iodinated derivatives of tyrosine

Thyroxine T4 Triiodothyronine T3

Prevalence of positive AMA titers increased with _____ as does the incidence of primary ___________

age hypothyroidism

this plasma protein has a low affinity for T3 and T4 but accounts for 10-20% of bound circulating hormone

albumin

TSH is released from the

anterior pituitary

Pendred syndrome

associated with mild hypothyroidism, goiter and hearing loss

Chronic overreplacement with levothyroxine maybe associated with

cardiac abnormalities, bone demineralization especially in postmenopausal women

What circulating thyroid antibodies are usually present in patients with autoimmune thyroid disease

circulating thyroid antibodies both antimicrosomal and antithyroglobulin

Disruptions in process of synthesis or thyroglobulin that results in block of protein transport causes

congenital hypothyroidism

serum TSH is more sensitive than serum T4 as a test for thyroid dysfunction because TSH can

detect subclinical thyroid disorders in which serum total T4 is normal

Greatest clinical value of thyroglobulin measurement is in the management of patients with

differentiated thyroid cancer

thyroid gland is unique within the endocrine system in that is has a large _____ called the _____ used for the storage of hormones and their precursors

extracellular space called the follicular lumen

Hormone release is initiated by the retrieval of thyroglobulin from the

follicular lumen

Principal usefulness of this test is in differentiating hyperthyroidism into

high-uptake or low-uptake states

Principal usefulness of the radioactive iodine uptake study is to differentiate _________ into high uptake or low-uptake states

hyperthyroidism

Point of obtaining serum T3 is to determine severity of ________ and confirm the diagnosis of suspected _________ in which serum T4 levels are normal or equivocal

hyperthyroidism and confirm diagnosis of suspected thyrotoxicosis

Myxedema coma is a late manifestation of_________ and is managed with

hypothyroidism, large disease of IV T4 and hydrocortisone

Pendrin, an apical membrane protein aids in releasing ______ into the follicular lumen

iodide

Current TSH assays may detect overreplacement with levothyroxine because TSH concentrations would be low or high?

low

A palpable hypofunctional nodule in the presence of Graves disease be suspicious for

malignancy

An elevated or increasing thyroglobulin level after initial surgery and ablation therapy suggests

persistence or recurrence of tumor

The presence of an elevated TSH is confirmation of

primary hypothyroidism

elevated TSH, to determine degree of hypothyroidism you obtain

serum T4 levels

m/c cause of acute suppurative thyroiditis

staphylococcal and streptococcal

Pts with few s/s of hyperthyroidism with normal or borderline elevated T3 and T4 and with suppressed serum TSH levels have

subclinical hyperthyroidism

Pt w/Graves disease who manifests thyroid ophthalmopathy should be treated with

surgery not radioactive iodine ablation to avoid complicating the ocular problems attributed to the disease

this is a tissue-specific protein that serves as a matrix for the synthesis of hormone and as a vehicle for its storage

thyroglobulin

TPO: thyroperoxidase is an enzyme responsible for combining _____ and ______ and forming

thyroglobulin and iodide forming T3 and T4

thyroid stimulating hormone is released by the ____________ by way of the __________ released by the hypothalamus

thyroid stimulating hormone by the anterior pituitary gland by way of the thyrotropin-releasing hormone

serum thyroglobulin measured by

thyroid uptake test and T3 uptake test

The cAMP generating assay is termed _________ detectable in 90-95% of hyperthyroid patient with

thyroid-stimulating immunoglobulin and is detectable in 90-95% of hyperthyroid patients with Graves disease

What is the most effective biochemical study for assessing thyrometabolic status is

thyrotropin

The most important plasma protein for thyroid hormones is________ accounts for nearly _____ of circulating hormone has a high affinity for _______

thyroxine-binding globulin TBG 75% T4

Radioimmunoassay remains standard for measuring serum

total T4

Another plasma protein that accounts for 10% of circulating T3 and T4 is ________.

transthyretin

TSH suppressive therapy is part of routine management in some pts with

well-differentiated thyroid carcinoma