Cohen Thyroid Physio/Patho Flashcards
For hyper-thyroid treatment; do you choose Methimazole or PTU?
Methimazole
less side effects, longer half life
Why does exogenous thyroid hormone result in an atrophied thyroid gland and LOW Radioiodine uptake?
Because TSH gets shut off, which is responsible for up-regulating the Na/I symporter as well as Pendrin
From the blood, sodium and Iodine enter follicular thyroid cells via Na/Iodide symporter. From follicular cells, the body uses ______ to bring Iodine into the colloid.
Pendrin
Thyroid Receptor _____ is linked to the liver, hypothalamus, and pituitary
Beta
Exogenous Thyroid hormone makes the thyroid feel ______
Tiny
Key difference between TSH-Secreting Pituitary Adenoma and a Toxic Thyroid Nodule? (2 answers)
- Low TSH in Toxic thyroid nodule (because it’s Primary)
- High or “inapp. norm) in TSH adenoma (because it’s secondary)
In pregnancy, hCG activates TSH also and Estrogen increases TBG. In early pregnancy what happens to total t4? Free t4? TSH?
- Total T4 goes up
- Free T4 slightly goes up because counter balanced with extra TBG
- TSH goes down, because the free T4 negatively feeds back and wins out
Of all the causes of hyperthyroidism, what is the only one where you see LOW THYROGLOBULIN?
Exogenous Thyroid Hormone
Formation of T4 and T3 are catalyzed by the enzyme _____, afterwards thyroglobulin gets endocytosed & combo’d w/ a lysosome to cleave & diffuse
Thyroperoxidase (TPO)
[Not Thrombopoietin]
If a patient has hypothyroidism because of improper de-iodinase activity, then you provide which medication which has a short half-life and high risk of over-treatment?
Liothyronine (T3)
In regards to thyroid function, what is Jod-Basedow Effect?
Mega Turn-on from excess iodine (hyper)
Since hCG is similar to TSH, what happens in pregnancy?
You would expect increase of activity
Diastolic HTN, Increased LDL & Triglyc is associated with ____Thyroidism
HYPO
What would the THYROGLOBULIN levels be in a patient with destructive thyroiditis versus in excessive intake of thyroid hormone?
- High in destructive
- Low in Excess intake
How do you distinguish destructive thyroiditis vs excessive intake of thyroid hormone?
Check Thyroglobulin levels
TSH serum levels are not a good test in _____ hypothyroidism
Central
The most common cause of primary Hypothyroidism in US is _____
Hashimoto’s (autoimmune); AKA Chronic Lymphocytic Thyroiditis
[Look for buttload of lymphocytes around follicles]
To treat hypothyroidism, normally you provide _____, which has a long half-life and a lower risk of overtreatment
Levothyroxine (T4)
In regards to thyroid function what is Wolff-Chaikoff Effect?
Auto Thyroid Shut-Off from too much Iodide (hypo)
Thyroid Receptor _____ is linked to the Heart, GI, and Bone
Alpha
T4 vs T3 Function
- T4: Reservoir
- T3: Active Form
What is the negative feedback for TSH?
T4 levels
Graves disease pathophys?
TSH antibodies activate thyroid
Systolic HTN, decreased LDL & Triglyc is associated with ____Thyroidism
HYPER
Methimazole (MMI) or Propythiouracil (PTU) will do what in regards to thyroid function?
Blocks production of T4/T3 by inhibiting TPO
2 Key causes of transient thyroiditis WITHOUT hyperthyroidism
- Transient Thyroiditis
2. Exogenous Thyroid Hormone
On Embryonic Day _____, a bilobed early thyroid forms lateral to the trachea
50
Hashimoto’s is autoimmune targeting _____
Thyroid gland
Thyroid Parafollicular cells AKA C-Cells produce ______
Calcitonin
Hormone levels expected in Graves?
Low TSH, High T4/T3
TSH is the perfect screening test for primary thyroid disease, but not if there is pituitary or hypothalamic problem. Why?
TSH may be in a “normal” range, yet you would want it to be higher to compensate for a loss.
What is best test for primary thyroid dysfunciton?
TSH levels
Acutely, if the thyroid gland gets destroyed what happens to T3/T4? What about thyroglobulin levels?
Everything will raise up acutely
List the three phases of the “Tri-phasic” Transient Thyroiditis often associated with viral illness or childbirth. Note that you should just provide supportive care, don’t provide meds usually.
- Burst of T4/T3 from destroyed gland release into blood
- TSH suppresion dunks everything low
- Successful recovery
Even though an adenoma and Graves will fully light up the thryoid in a radioactive scan, Describe the TSH levels in a TSH-producing adenoma vs Graves (2 answers)
- TSH would be high/(innappropriate norm) in adenoma
- TSH would be low in graves
Is active thyroid hormone free or bound?
Free
