2.1.1 AI Summary: Intro to Thyroid

What hormone does the hypothalamus release to regulate thyroid function?

TRH

What hormone does the anterior pituitary release in response to hypothalamic signaling?

TSH

What gland is stimulated by thyroid-stimulating hormone?

Thyroid gland

What hormones are produced by the thyroid gland?

T3 and T4

Which thyroid hormone is more biologically active?

T3

Which thyroid hormone is produced in greater quantity by the thyroid gland?

T4

What process converts T4 into the active hormone?

Peripheral deiodination

What inactive molecule can T4 be converted into?

Reverse T3

What transporter brings iodide into thyroid follicular cells?

Sodium-iodide symporter

What transporter moves iodide into the colloid?

Pendrin transporter

What enzyme adds iodine to tyrosine residues?

Thyroid peroxidase

What is formed when tyrosine is iodinated with one iodine?

Monoiodotyrosine (MIT)

What regulates TSH secretion from the pituitary?

TRH

Is routine screening recommended in non-pregnant asymptomatic adults?

No

In which populations should TSH screening be done?

- Hx of T1DM or other autoimmune disease

- Fx of thyroid disease, goiter, and previous hyperthyroidism

- Hx of neck radiation to the thyroid or thyroid surgery

- Anyone > 60 yrs, on meds containing iodine (ex. amiodarone), low iodine intake

What is the most sensitive marker for thyroid function?

TSH

What lab is used to further evaluate thyroid function after abnormal TSH?

Free T4

What diagnostic test helps determine cause of hyperthyroidism?

Radioactive iodine uptake

What pattern indicates central hypothyroidism?

Low TSH with low T4 and T3

What pattern indicates primary hypothyroidism?

High TSH with low T4 and T3

What pattern indicates primary hyperthyroidism?

Low TSH with high T4 and T3

What pattern indicates secondary hyperthyroidism?

High TSH with high T4 and T3

What are common symptoms of hypothyroidism?

Fatigue, weight gain, constipation, edema

What are common symptoms of hyperthyroidism?

Weight loss, increased heart rate, increased blood pressure, buldging eyes

What patient populations should be screened for thyroid disease?

Those with autoimmune disease, thyroid history, or prior thyroid intervention

What medication class may warrant thyroid monitoring due to iodine content?

Iodine-containing medications

What condition is defined by elevated TSH with normal free T4?

Subclinical hypothyroidism

What role does T4 serve physiologically?

Reservoir for active hormone

What is the function of thyroglobulin in the thyroid?

Template for thyroid hormone synthesis

What type of transport is the sodium-iodide symporter?

Secondary active transport

What feedback mechanism regulates thyroid hormone levels?

Negative feedback loop

What drugs treat hyperthyroidism?

Drugs for hypothyroidism