Steroid Biosynthesis Flashcards
General Steroid Hormone Synthesis Steps
Desmolase turns cholesterol into pregnenolone
Pregnenolone turned into Progesterone
Progesterone is precursor to steroid hormones
ACTH Actions
Increases lipoprotein uptake and adrenal cortex cholesterol
Increased steroidogenic enzyme gene expression (desmolase)
Cortisol
Actions and Associated Illness
Increases gluconeogenesis and blood pressure
Anti-inflammatory actions
Infant Respiratory Distress Syndrome
Premies don’t have glucocorticoids to start surfactant synthesis
Aldosterone
Actions and Associated Illness
Increases sodium/water reabsorption and blood pressure
Congenital Adrenal Hyperplasia
11-Beta Hydroxylase Defect
Pathogenesis and Presentation
Causes increased corticosterone precursors and androgens and decreased aldosterone
11-deoxycorticosterone causes HTN and Sodium/Water retention
Androgens cause Hirsutism
Steroid Binding Globulins
Synthesis and Types
Corticosteroid-Binding Globulin and Sex Steroid-Binding Globulin both synthesized in liver
CYP17A1 Deficiency
Defect and Effect
Defect in both 17-alpha hydroxylase and 17,20 Lyase
Stops the production of testosterone from progesterone
Causes impaired puberty and underdeveloped genitalia
Steroid Synthesis Regulation
Hormones and Male/Female Difference
ACTH and LH increase desmolase activity
FSH increases aromatase activity
Female Progesterone decreased by GnRH
Male Testosterone decreased by GnRH
Vitamin D Synthesis
CYP2R1 gene increases 25-hydroxylase in liver
Increases 25-hydroxycholecalciferol (Vit D3)
Kidney uses 1-alpha hydroxylase to turn D3 into 1,25-hydroxycholecalciferol
21-Alpha Hydroxylase Defect
Pathogenesis and Presentation
Causes increased ACTH and Progesterone and decreased aldosterone
Salt wasting and ambiguous genitalia
95% of Congenital Adrenal Hyperplasia
