Endocrinology Part 1 Flashcards
What are the sex steroids?
Progesterone, androgens, and estrogens
What is the main minaralocorticoid?
Aldosterone
What is the main glucocorticoid?
Cortisol
How are all steroid hormones made?
Cystolic cholesterol is converted to mitochondrial cholesterol by StAR which is then converted to pregnenolone by SCC.
How are steroids released from the cell?
Diffuse out of the cell (non-vesicular storage)
How are steroids transported? Metabolized/excreted?
Transport by binding proteins
Metabolized into an inactive form then excreted by either the liver or the kidney
What carrier protein does cortisol use?
Transcortin
What carrier protein do thyroid hormones use?
Thyroxine-binding Globulin (TBG)
What carrier protein do most steroid hormones use?
Albumin (it is non-specific)
What is the MOA of ketoconazole?
Inhibits SCC and CYP17
Decrease the synthesis of all steroids
What is ketoconazole used for?
Antifungal agent
Decrease tumor production of steroids
What is the MOA of finasteride?
Inhibits 5-alpha-reductase
Decrease the synthesis of dihyrdotestosterone (DHT)
What is finasteride used for?
Alopecia and BPH
What precautions should be taken with finasteride?
Do not touch if pregnant
What is the MOA of letrozole?
Inhibit aromatase
Decreases estrogens
What is letrozole used for?
Estrogen Receptor (+) Breast Cancer
What is the MOA of metyrapone?
Inhibit 11-beta-hyroxylase
Decrease cortisol
What is metyrapone used for?
Adrenal cortex excess production
How are hormones synthesized from peptides/proteins made?
Amino acids link to form a pre-prohormone –> prohormone –> hormone
How are peptide/protein hormones released?
Exocytosis from a vesicle
How are peptide/protein hormones transported? Metabolized/excreted?
Transported by some binding proteins but mostly water soluble and move in plasma
They are endocytosed and degraded by proteases
What are the major catecholamines?
Dopamine, norepinephrine, epinephrine
How are catecholamines synthesized?
Tyrosine –> L-DOPA –> dopamine –> norepinephrine –> PNMT converts it to epinephrine
How are catecholamines released? Transported? Metabolized/excreted?
Released by exocytosis from vesicles
Transported in plasma (water soluble) or bound to albumin
Uptake and breakdown by monamine oxidase (MAO) or catechol-o-methyltransferase (COMT)
What is the common metabolite from catecholamine metabolism?How is it used diagnostically?
Vanillylmandelic acid (VMA)
If the patient has a catecholamine secreting tumor VMA will be found in high amounts in urine
What are two hormones are amino acid derivatives?
Thyroid hormones and melatonin