ENDOCRINE NB

Question 1

Q: Which organs make up the endocrine system?

Answer 1

A: Hypothalamus, pituitary gland, thyroid gland, parathyroid gland, pancreas, adrenal gland.

Question 2

: What hormones are produced by the thyroid gland?

Answer 2

:
A: Thyroxine (T4), Triiodothyronine (T3), and Calcitonin.

Question 3

Q: What are the stages of thyroid hormone production?

Answer 3

Iodide ingestion and absorption into the blood.
Iodide trapping by sodium-iodide symporter into the thyroid gland.
Thyroglobulin (Tg) secretion into follicles by the ER and Golgi.
Oxidation of iodide to iodine by thyroid peroxidase.
Iodine binding to Tg (organification) via iodinase enzyme.
Formation of T3 and T4 through coupling of monoiodotyrosine and diiodotyrosine.
Pinocytosis of the Tg-hormone complex into cells, cleavage of Tg, and hormone release.

Question 4

: Which enzyme is responsible for oxidation, organification, and coupling in thyroid hormone production?

Answer 4

:
A: Thyroid peroxidase.

Question 5

Name the radiopharmaceuticals used for thyroid imaging.

Answer 5

Technetium 99m pertechnetate (99mTc O4⁻)
Iodine 131 (I-131) : gamma emitter
Iodine 123 (I-123): gamma and beta emitter
Iodine 124 (I-124): positron emitter

Question 6

: What are the clinical uses of radiopharmaceuticals in thyroid conditions?

Answer 6

:

Hyperthyroidism (Graves’ disease, toxic adenoma, toxic multinodular goiter)
Well-differentiated thyroid cancer (imaging and therapy).

Question 7

Q: What characterizes Graves’ disease?
A:

Answer 7

Autoimmune disease.
High levels of Thyroid Stimulating Immunoglobulin (TSI).
Increased T3 and T4, decreased TSH.
Hyperthyroidism with thyrotoxicosis.

Question 8

Q: What is toxic adenoma?

Answer 8

A: A hyperfunctioning nodule in the thyroid gland.

Question 9

What is toxic multinodular goiter?
.

Answer 9

A: Multiple hyperfunctioning nodules in the thyroid gland.

Question 10

Q: What hormone is produced by the parathyroid gland?

Answer 10

A: Parathyroid hormone (PTH).

Question 11

: What radiopharmaceutical is used for parathyroid imaging?

Answer 11

:
A: 99mTc Sestamibi.

Question 12

Why does 99mTc Sestamibi target hyperfunctioning parathyroid glands?

Answer 12

A: Hyperfunctioning glands have higher mitochondrial content, which attracts and retains the tracer.

Question 13

Q: What is the embryological origin of the adrenal medulla?
.

Answer 13

A: Neural crest cells.

Question 14

Q: What cells make up the adrenal medulla and what do they produce?

Answer 14

A: Chromaffin cells; they produce and store epinephrine and norepinephrine.

Question 15

What are tumors of the adrenal medulla called?
A: Pheochromocytomas.

Answer 15

What are tumors of the chromaffin cells in adrenal medulla called?
A: Pheochromocytomas.

Question 16

Q: What radiopharmaceuticals are used for adrenal medulla imaging?
A

Answer 16

A:

Iodine 123 MIBG- gamma emitter
Iodine 131 MIBG - gamma and beta emitter

Question 17

Q: What is MIBG?

Answer 17

A: MetaIodoBenzylGuanidine, an analogue of norepinephrine.