Exam
Steroid Hormone Pathway
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Steroid Hormone Pathway
, Sex Hormone Synthesis, Cortisol Synthesis, Aldosterone Synthesis
Physiology
Cholesterol
is precursor for 5 steroid hormone classes
Progestagens (e.g.
Progesterone
)
Glucocorticoid
s (e.g. Cortisol)
Mineralcorticoids (e.g. Aldosterone)
Androgens (e.g. Testosterone)
Estrogen
s
Synthesis sites
Adrenal cortex:
Glucocorticoid
s, Mineralcorticoids
Women
Corpus luteum: Progestagens
Ovary
:
Estrogen
s
Men
Testis
: Testosterone
Conditions related to enzyme deficiencies
Congenital Adrenal Hyperplasia
21-Hydroxylase deficiency is most common
Step 1
Steroid Synthesis -
Cholesterol
to Precursors
Cholesterol
converted to Pregnenolone
Stimulated by ACTH release from anterior pituitary
Key enzyme: Desmolase
Pregnenolone converted to
Progesterone
Pregnenolone is precursor of all steroids
Key enzyme: 3-B-Hydroxysteroid Dehydrogenase
Progesterone
converted to 17-a-hydroxyprogesterone
Key enzyme: 17-Hydroxylase
17-a-hydroxyprogesterone is precursor
Cortisol Synthesis (Go to step 2)
Aldosterone Synthesis (Go to Step 4)
17-a-hydroxyprogesterone converted to
Androstenedione
Key enzyme: 3-B-Hydroxysteroid Dehydrogenase
Androstenedione
is sex hormone precursor (see Step 3)
Estrone
Testosterone
Estradiol
Step 2
Cortisol Synthesis from 17-a-hydroxyprogesterone
17-a-hydroxyprogesterone converted to 11-Deoxycortisol
Key enzyme: 21-Hydroxylase
Most common enzyme deficiency in steroid synthesis
Congenital Adrenal Hyperplasia
(with
Virilization
)
11-Deoxycortisol converted to Cortisol
Key enzyme: 11-Hydroxylase
Enzyme deficiency related condition
Congenital Adrenal Hyperplasia
(with
Virilization
)
Cortisol
Step 3
Sex Hormones from
Androstenedione
Androstenedione
converted to Estrone or
Androstenedione
converted to Testosterone
Testosterone converted to Estradiol
Step 4
Aldosterone from
Progesterone
Progesterone
converted to 11-Deoxycorticosterone
Key enzyme: 21-Hydroxylase
11-Deoxycorticosterone converted to Cortisosterone
Key enzyme: 11-Hydroxylase
Corticosterone converted to Aldosterone
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