A 6 week infant with ambiguous genitalia (as shown below) presents with an episode of dehydration & shock requiring hospitalization. What is the electrolyte abnormality that you expect in this baby?
**Core Concept**
The underlying condition in this scenario is likely **Congenital Adrenal Hyperplasia (CAH)**, a group of autosomal recessive disorders that affect the adrenal glands, leading to impaired production of **cortisol** and **aldosterone**. This impairment results in an overproduction of **androgens**, causing **virilization** of female infants and **ambiguous genitalia**.
**Why the Correct Answer is Right**
In CAH, the deficiency of **21-hydroxylase** enzyme is the most common cause, leading to a decrease in the production of **cortisol** and **aldosterone**. The lack of **aldosterone** results in an inability to retain **sodium** and **water**, causing **dehydration** and **hypotension**. Additionally, there is an excessive loss of **potassium**, leading to **hypokalemia** is not typically the primary issue, but rather **hyponatremia** and **hyperkalemia** due to the lack of **aldosterone**.
**Why Each Wrong Option is Incorrect**
**Option A:** This choice might seem plausible but does not directly relate to the primary defect in CAH.
**Option B:** Similarly, this option does not directly address the electrolyte imbalance caused by CAH.
**Option D:** This choice is incorrect as it does not align with the expected electrolyte abnormality in CAH.
**Clinical Pearl / High-Yield Fact**
In infants with CAH, particularly those with the salt-wasting form, **hyponatremia** and **hyperkalemia** are critical electrolyte abnormalities to recognize, as they can lead to severe dehydration and shock if not promptly treated.
**Correct Answer:** D. Hyperkalemia