Endocrinology Book


Steroid Hormone Pathway

Aka: Steroid Hormone Pathway, Sex Hormone Synthesis, Cortisol Synthesis, Aldosterone Synthesis
  1. See Also
    1. Adrenal Gland Physiology
    2. Serum Cortisol
  2. Pathophysiology
    1. Aldosterone
      1. Hyperaldosteronism
    2. Cortisol
      1. Addison's Disease (Adrenal Insufficiency)
      2. Cushings Disease
    3. Androgens
      1. Congenital Adrenal Hyperplasia
        1. 21-Hydroxylase deficiency is most common
    4. Epinephrine and Norepinephrine (Adrenal Medulla)
      1. Pheochromocytoma
  3. Physiology: General
    1. Images
      1. AdrenalFunction.png
    2. Cholesterol is precursor for 5 steroid Hormone classes
      1. Progestagens (e.g. Progesterone)
      2. Glucocorticoids (e.g. Cortisol)
      3. Mineralcorticoids (e.g. Aldosterone)
      4. Androgens (e.g. Testosterone)
      5. Estrogens
    3. Synthesis sites
      1. Adrenal Cortex: Glucocorticoids, Mineralcorticoids
      2. Women
        1. Corpus luteum: Progestagens
        2. Ovary: Estrogens
      3. Men
        1. Testis: Testosterone
  4. Physiology: Step 1 (Steroid Synthesis - Cholesterol to Precursors)
    1. Cholesterol converted to Pregnenolone
      1. Stimulated by ACTH release from anterior pituitary
      2. Key enzyme: Desmolase
    2. Pregnenolone converted to Progesterone
      1. Pregnenolone is precursor of all steroids
      2. Key enzyme: 3-B-Hydroxysteroid Dehydrogenase
    3. Progesterone converted to 17-a-hydroxyprogesterone
      1. Key enzyme: 17-Hydroxylase
      2. 17-a-hydroxyprogesterone is precursor
        1. Cortisol Synthesis (Go to step 2)
        2. Aldosterone Synthesis (Go to Step 4)
    4. 17-a-hydroxyprogesterone converted to Androstenedione
      1. Key enzyme: 3-B-Hydroxysteroid Dehydrogenase
      2. Androstenedione is sex Hormone precursor (see Step 3)
        1. Estrone
        2. Testosterone
        3. Estradiol
  5. Physiology: Step 2 (Cortisol Synthesis from 17-a-hydroxyprogesterone)
    1. 17-a-hydroxyprogesterone converted to 11-Deoxycortisol
      1. Key enzyme: 21-Hydroxylase
      2. Most common enzyme deficiency in steroid synthesis
        1. Congenital Adrenal Hyperplasia (with Virilization)
    2. 11-Deoxycortisol converted to Cortisol
      1. Key enzyme: 11-Hydroxylase
      2. Enzyme deficiency related condition
        1. Congenital Adrenal Hyperplasia (with Virilization)
    3. Cortisol
  6. Physiology: Step 3 (Sex Hormones from Androstenedione)
    1. Androstenedione converted to Estrone or
    2. Androstenedione converted to Testosterone
      1. Testosterone converted to Estradiol
  7. Physiology: Step 4 (Aldosterone from Progesterone)
    1. Progesterone converted to 11-Deoxycorticosterone
      1. Key enzyme: 21-Hydroxylase
    2. 11-Deoxycorticosterone converted to Cortisosterone
      1. Key enzyme: 11-Hydroxylase
    3. Corticosterone converted to Aldosterone
    4. Aldosterone
      1. See Sodium and Water Homeostasis

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