Thyroid Function (lect 4) Flashcards
Describe Thyroid Glands
two types of cells follicular and parafollicular
Describe follicular thyroid glands
single
secrete
single layer of epithelial cells, spherical, secrete thyroid hormones
hormones in lumina
Describe the follicular thyroid hormones
T4 - L thyroxine
T3 - L- trii
RT3 - reverse T3, bioinactive
Describe the parafollicular thyroid gland
secrete calcitonin
Function of thyroid glands
aid
rate
grow
p
c
aid in regulation of metabolic functions
rate of O2/Heat
growth/sexual maturaty/proteins/carb metabolism
Describe H-P-T axis
what is released by hypoth stim and anterior pit secretes?
what regs synth/release of thyroid hormones?
TRH released by the hypothal stim anterior pit to secrt TSH
TSH reg synth and release of thyroid hormones
Secretion of TSH is regulated by
what hormones?
what inhibits/
what stimulates the inhibitor? then causes?
TRH, Stomatostatin, F13, FT4
Stomastatin is an inhibitor
FT3/FT4 - stim hypothal. to sec stomastatin/negative feedback
T/F 30% of T4 goes through the monod. in tissues to prod. T3
False its 40%
Describe RT3
45% Convert to rt3
Bioinactive
Thyroid hormones circulate in blood bound to
TBG, TB alb, TB pre-Alb
What is the principle carrier protein
TBG
T/F FT3/FT4 are physiologically inactive
false they are active
T/F T3 is 4-5x more metabolically potent than T4
TRUE
Describe tests for thyroid function
generations?
TSH:
assesses function
third gen sensitivity subclinical disease
Describe subclinical hypothyroidism
TSH
FT4
Hyperthyroidism:
TSH
FT4
TSH minimal incr
FT4 within range
hyperthyroidism: TSH dec
FT4 normal
Describe thyroxine (T4)
bound?
alterations lead to?
99.9% protein bound, alteration leads to outside normal range
Describe Trii (T3)
produces____ of___
produces 20% batom iodine
Describe free thyroxine (FT4)
most is?
able to?
bio?
small frac. of total because most is bound, able to enter the tissues
bioactive
Describe Free Trii (FT3)
elevated in?
what fraction?
hyperthyroid are elevated, low fraction measured less
Describe thyroglobulin Ab
destruction…may lead to?
destruction through autoimmune response may result in Tg leakage into blood stream
Describe TPO ab
activate…
role in?
activate/compliment role in path of hypothyroidism
Describe TrAB Ab
all ____ by TRAB
all autoimmune thyrotoxicosis by TRAB
Describe the thyroid autoimmune disorders (2)
graves/hashimotos
Describe graves disease
what is +?
hyperthyroidism, goiter growth of gland TSHRAB (+)
Describe Hashimotos thyroiditis
another name?
Ab leads to dec____ and ____ of gland
what Ab?
hypothyroidism, chronic lymph thyroiditis, Ab lead to dec thyroid hormone production and destruction of gland
TPO test Ab
Describe nuclear medicine eval
what is the acronym
low uptake
high uptake?
radioactive idodine uptake (RAIU)
Low uptake suggests gland is metab. inactive
high uptake suggests met. active prod slight amounts of thyroid hormone
Describe Thyroid Ultrasound
high frequency sound waves to thyroid gland, non-palpable nodules
Describe fine needle respiration
FNA biopsy first step and most accurate, prompt ID/treatment
Describe Hypothyroidism
TSH
FT4
genders/ages
sympt
Low FT4 with norm/high TSH
common, women over 65
low body temp, yellow, hair loss
Primary hypothyroidism
2
3
p: hashimotos (anti-TPO)
treat goiter
excessive iodine intake
2- hypopitu
3 - hypothal dysfunct
Describe Thyrotoxicosis
peripheral tissues with
excess
I
L
G h
periph tissues present w/ excess thryoid hormone
result of excess thyhroid ingestion, leakage from follicles, excessive gland hormone production
Describe hyperthyroidism
autoim activates?
15% have ….
symptoms?
graves, Autoimune activates TSHR, 15% close relative, goiter, orange peel skin, radioactive iodine/meds
Describe toxic adenoma/multinodular goiter
what kind of dysfunction
autonom…no what is needed
radioactive iodine does what?
hyperthyroidism, poss. palpable nodules
autonomously func. thyroid issue - no TSH needed
radioactive iodine tends to KILL hyperacitve nodule/leaves in tissue
Drug induced thyroid dysfunction
Amio…
37% MW is?
Amiodarone - thryoid diease
cardiac arrythmias 37% MW is iodine
Describe Subacute thyroiditis
assoc with…..
most common form?
gender?
assoc. w/ inflam of thyroid, leakage, repair of gland
post partum thyroidtiis most common form .5-9% women
Describe nonthyroidal illness and thyroid nodules
TSH/FT4/FT3
what is common
kinds of pts?
critically ill/hospitalized pts low TSH, Low T3 low FT4
nodules common
less than 10% are cancer
