High Yield Topics-Endocrine Flashcards
The type of vitamin D that is obtained from exposure of skin to sun or through ingestion from dairy products
vitamin D3 (aka. Cholecalciferol)
The type of vitamin D that is obtained from ingestion of plants, fungi, and yeasts
vitamin D2 (Ergocalciferol)
- STUDY AID: think of ERGOsterol in FUNGAL cell membrane
Both cholecalciferol and ergocalciferol convert into what storage and active forms?
- 25-OH D3 (storage form)
- 1,25-(OH)2D3 (active form; calcitriol)
cholecalciferol and ergocalciferol convert into storage form in what organ?
liver
cholecalciferol and ergocalciferol convert into active form (calcitriol) in what organ?
kidney (PCT)
Why is vitamin D required to increase serum Ca+2 level?
Active Vitamin D increases intestinal absorption of Ca+2 (and PO43- also)
Enzyme that converts inactive/storage form (25-hydroxyvitamin D) to active form (1,25-dihydroxyvitamin D)
1α-hydroxylase
- mainly in the kidneys
A disorder causing ↑ β-adrenergic receptor expression, leading to ↑ catecholamine effects; presents with SYSTOLIC hypertension, sweating, hot intolerance, diarrhea, warm/moist skin, palpitations/tachycardia, weight loss, hyperreflexia, and can mimic anxiety disorder
Hyperthyroidism
An autoimmune disordercaused by thyroid-“stimulating” antibody that binds and stimulates TSH receptors on thyroid; presents with hyperthyroid symptoms
Graves Disease
Caused by orbital fibroblasts
and T-Cells activation by thyrotropin (aka. TSH) receptor antibodies –> cytokine release (TNF-a, IFN-Y) –> glycosaminoglycan (GAG) deposition in eyes –> expansion/inflammation of extraocular muscles –> exophthalmos (protruding eyes)
Graves Ophthalmopathy
Lab findings of Hyperthyroidism
TSH, T4, T3, TBG
TSH:↓
T4: ↑
T3: ↑
TBG: normal
Improve Graves ophthalmopathy by decreasing the severity of inflammation and reducing the excess extraocular volume
Glucocorticoids
Caused by accumulation of GAGs in leg skin due to activation of dermal fibroblasts by thyroid-stimulating antibodies
Pretibial myxedema
The adrenergic receptor symptoms (systolic hypertension, sweating, hot intolerance, palpitations/tachycardia, hyperreflexia) can be relieved by what drug?
β blockers
Drugs that ↓ the formation of TSH (thyrotropin) via inhibition of thyroid peroxidase, the enzyme responsible for both iodine organification and coupling of iodotyrosines
Thioamides
- methimazole
- PTU
Which Thioamide also decreases the peripheral conversion of T4 to T3?
PTU
A serious complication of Thioamides that results in granulocyte destruction and consequent neutropenia; initially presents with fever, sore throat, and oral ulcerations
Agranulocytosis
If drug-induced agranulocytosis is suspected, what should be done?
Discontinue the drug and obtain CBC w/ diff to confirm diagnosis
A condition characterized by ↑ free T4, suppressed TSH, and low/undetectable TG; occurs with surreptitious levothyroxine abuse, use of animal-sourced thyroid supplements, and erroneous dosing of thyroid replacement therapy
Exogenous Hyperthyroidism
aka. Thyrotoxicosis
The lack of TSH stimulation continued by Exogenous Hyperthyroidism (levothyroxine) can lead to
ATROPHIC thyroid follicles
The main regulator of lipid metabolism by stimulating the mobilization and degradation of lipids (TG)
Thyroid hormone
- TH ↓TG
HLA (Human MHC) associated with Graves disease (2)
- HLA-DR3
2. HLA-B8
Caused by hyperfunctioning follicular cells (hot nodules) due to TSH receptor mutations and not due to increased TSH; ↑ release of T3 and T4
Toxic Multinodular Goiter
(Hot/cold) nodules produce excess thyroid hormone, show up on the scan because they take up more of the isotope than normal thyroid tissue, and almost always are NONcancerous
Hot nodules