You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Most common type of Congenital adrenal hyperplasia (CAH)? and explain in detail?
Ans. a (21-hydroxylase deficiency) (Ref OP Ghai 7th/ p. 492; H-17th/p. 2267).The 21-hydroxylase deficiency is the commonest form of CAH, accounting for > 90% of all cases.Type of CAHFeatures1.21-hydroxylase deficiency# Most common cause of ambiguous genitalia at birth# Salt-losing form of CAH# Episodes of acute adrenal insufficiency with hyponatremia, hyperkalemia, dehydration, and vomiting.# These infants and children often crave salt.# Deficits in both cortisol and aldosterone secretion.2.11-hydroxylase deficiency# Ambiguous genitalia# Hypertensive form of CAH# Diagnosis is confirmed by demonstrating increased levels of 11-deoxycortisol in the blood or increased amounts of tetrahydro-11-deoxycortisol in the urine.3.3b hydroxylase deficiency# Very high levels of urine DHEA with low levels of pregnanetriol and of cortisol metabolites in urine are characteristic.# Marked salt-wasting may also occur.4.17 a-hydroxylase deficiency# Female or ambiguous.# CAH# Hypertension due to | corticosterone & 11-deoxycorticosterone, except in isolated 17,20-lyase deficiency.5.Adults with late-onset adrenal hyperplasia (partial deficiency of CYP21A2, CYP11B1, or 3-HSD2)# Characterized by normal or moderately elevated levels of urinary 17-ketosteroids and plasma DHEA sulfate.# A high basal level of a precursor of cortisol biosynthesis (such as 17-hydroxy- progesterone, 17-hydroxypregnenolone, or 11-deoxycortisol), or elevation of such a precursor after ACTH stimulation, confirms the diagnosis of a partial deficiency.# Measurement of steroid precursors 60 min after bolus administration of ACTH is usually sufficient.# Adrenal androgen output is easily suppressed by the standard low-dose (2 mg) dexamethasone test.