jay1
Forum Junior
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A neonate has ambiguous genitalia. In the first 48 hours of life, the neonate feeds poorly and becomes dehydrated. Which of the following is the most likely diagnosis?
A) 21-Hydroxylase deficiency
B) 5α-Reductase deficiency
C) True hermaphroditism
D) 17-Hydroxylase deficiency
E) Androgen insensitivity syndrome
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| Sakaki-
Forum Senior
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A) 21-hydroxylase deficiency (resulting in deficient formation of cortisol and aldosterone)
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| Bela
Forum Guru
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sakaki,
I see ur point but why not 17 hydroxilase def? Wouldn't that have the same effect on zona glomerulosa/fasciculata? I mean, you wouldn't get aldosterone and cortisol anyway. Please explain.
Appreciate it!
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La vita e bella!
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| Sakaki-
Forum Senior
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17-hydroxylase deficiency would result in hypertension due to excess mineralocorticoid production. Deoxycorticosterone (whose synthesis is proximal to the block) is increased, and it possesses mineralocorticoid activity (the high blood pressure results in suppression of the RAA system, usually resulting in decreased aldosterone levels). The hypertension is thought to result from the DOC excess.
Anyways, 21-hydroxylase deficiency is far more prevalent than 17-hydroxylase deficiency (former accounts for more than 90% of cases of CAH, while 17-hydroxylase deficiency is extremely rare).
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| UMASS
Forum Junior
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why you did not choose (c) guys ?
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| Sakaki-
Forum Senior
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That doesn't account for the dehydration.
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| Bela
Forum Guru
Topics: 76
Posts: 412
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umass,
Initially I thought of C but they'd give more info to lead us think toward true hermaphrodism.
Thnx sakaki. Yes, now it makes sense. With 17 OHlase, u'd have high 11 deoxycorticosterone and therefore increased Na reabsorption. The H2O would follow and the baby wouldn't be dehydrated.
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La vita e bella!
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