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What is A 1-month old baby presents with frequent vomiting and failure to thrive. There are features of moderate dehydration. Blood sodium is 122 mEq/1 and potassium is 6.1 mEq/1. The most likely diagnosis is: and explain in detail?
Congenital adrenal hyperplasia due to 21-hydroxylase deficiency (21-OH CAH), in all its forms, accounts for over 95% of diagnosed cases of congenital adrenal hyperplasia. Hence "CAH" in most contexts refers to 21-hydroxylase deficiency. Ref: Kliegman, Behrman, Jenson, Stanton (2008), Chapter 577, "Congenital Adrenal Hyperplasia", In the book, "Nelson's Textbook of Pediatrics", Volume 2, 18th Edition, New Delhi, Page 2360; Harrison's Internal Medicine, 17th Edition, Page 2267.