20 yrs old young girl, presents with history of rapidly developing hirsutism and amenorrhea with change in voice. To establish a diagnosis you would like to proceed with which of the following tests in blood:
**Core Concept**
The patient's presentation suggests an androgen excess disorder, likely due to a hormonal imbalance. The clinical features of hirsutism, amenorrhea, and voice changes are characteristic of hyperandrogenism, which can be caused by various conditions, including polycystic ovary syndrome (PCOS), congenital adrenal hyperplasia (CAH), or androgen-secreting tumors.
**Why the Correct Answer is Right**
To establish a diagnosis, measuring the levels of androgens and their precursors in the blood is crucial. The most relevant test would be to measure the levels of 17-hydroxyprogesterone (17-OHP), a precursor of cortisol and androgens. Elevated levels of 17-OHP can indicate congenital adrenal hyperplasia (CAH), particularly 21-hydroxylase deficiency, which is a common cause of androgen excess in females. Additionally, measuring the levels of testosterone and dehydroepiandrosterone sulfate (DHEA-S) can also provide valuable information about the source of androgen excess.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not directly relevant to the diagnosis of androgen excess disorders. While it may be useful in assessing thyroid function, it does not provide information about androgen levels or their precursors.
**Option B:** Measuring the levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) can provide information about the pituitary-gonadal axis, but it is not the most relevant test in this scenario.
**Option C:** Measuring the levels of cortisol can provide information about the hypothalamic-pituitary-adrenal (HPA) axis, but it is not directly relevant to the diagnosis of androgen excess disorders.
**Option D:** Measuring the levels of sex hormone-binding globulin (SHBG) can provide information about the binding of androgens and estrogens, but it is not the most relevant test in this scenario.
**Clinical Pearl / High-Yield Fact**
In cases of androgen excess, it is essential to consider the possibility of congenital adrenal hyperplasia (CAH), particularly 21-hydroxylase deficiency. This condition can present with a range of clinical features, including hirsutism, amenorrhea, and voice changes, and can be diagnosed by measuring the levels of 17-hydroxyprogesterone (17-OHP) in the blood.
**Correct Answer:** C.