Adrenal cortex synthesize steroids.
Mnemonic: GFR – Salt, Sugar, Sex
- Zona gomerulosa: Salt (Aldosterone)
- Zona fasciculata: Sugar (Cortisol)
- Zona reticulosa: Sex (Testosterone)
Congenital adrenal hyperplasia (CAH)
Mnemonic: Remember the mnemonic GFR, first layer of cortex synthesizes aldosterone and the last layer synthesizes sex steroids. So, the numberals in enzyme can be assumed to represent following:
- 1st digit: Blood pressure
- 2nd digit: Testosterone
The “1” looks like an up arrow, hence, it signifies “increase“.
All the 3 conditions are associated with the hypertrophy of adrenals due to high levels of ACTH (lack of suppression). In all 3 conditions corticosteroid is decreased. The most common one is due to 21 hydroxylase deficiency.
1. 11 hydroxylase deficiency:
- 1 – Increased blood pressure (hypertension)
- 1 – Increased testosterone (virilization in females)
2. 21 hydroxylase deficiency:
- 2 – Decreased blood pressure (hypotension)
- 1 – Increased testosterone (virilization in females)
3. 17 hydroxylase deficiency:
- 1 – Increased blood pressure (hypertension)
- 7 – No increase in testosterone
- Adrenal steroidogenesis is regulated by ACTH from anterior pituitary gland.
- Circulating level of plasma cortisol is a key player in the hypothalamic-pituitary-adrenal feedback system and exerts a negative feedback effect on the secretion of ACTH .
- ACTH secretion increases due to decrease in cortisol secretion as in CAH (loss of negative-feedback on ACTH) resulting in:
- Overstimulation of the adrenals – hyperplasia
- Stimulation of excessive synthesis of the adrenal products of those pathways unimpaired by an enzyme deficiency and causes an accumulation of precursor molecules in pathways blocked by an enzyme deficiency.
3 B-HSD is involved in synthesis of all 3 steroids involved in salt, sugar and sex.
Mnemonic: 3 involves all 3
- Hence, deficiency of 3 B-HSD leads to decrease in all 3 steroids.
21 OH and 11 OH are involved in synthesis of salt and sugar only.
- Hence, deficiency of 21 OH and 11 OH enzymes lead to increase in sex steroids.
- In 11 OH deficiency, hypertension occurs due to accumulation of Deoxycorticosterone (DOC) which has mineralocorticoid activity.