**Question:** A 28-year-old lady has put on weight (10 kg over a period of 3 years), and has oligomenorrhea! followed by amenorrhea for 8 months. The blood pressure is 160/100 mm of Hg. Which of the following is the most appropriate investigation?

A. Thyroid function test
B. Prolactin level
C. Hormonal profile
D. Renal profile

**Core Concept:**

The presented symptoms and signs in this case suggest a possible endocrinological issue involving the hypothalamic-pituitary-ovarian axis. Oligomenorrhea and amenorrhea can be caused by a variety of factors, including hormonal imbalances, obesity, or hypertension. However, the specific investigation needed would depend on the suspected underlying cause.

**Why the Correct Answer is Right:**

In this scenario, the correct investigation to perform is **B. Prolactin level.** This is due to the patient's presentation of oligomenorrhea and amenorrhea, along with hypertension. Prolactin is a hormone produced by the anterior pituitary gland that plays a significant role in regulating the menstrual cycle and lactation. Elevated prolactin levels can lead to the suppression of gonadotropin-releasing hormone (GnRH) release, thereby causing hypothalamic-pituitary-ovarian axis dysfunction and ultimately leading to oligomenorrhea, amenorrhea, and hypertension.

**Why Each Wrong Option is Incorrect:**

A. **Thyroid function test (A)** is not directly related to the presented symptoms and signs. Hypothyroidism can lead to oligomenorrhea, but it is less likely to cause hypertension.

C. **Hormonal profile (C)** is a broad term encompassing various hormones and tests that may be relevant in a more comprehensive evaluation. However, in this specific case, focusing on prolactin levels is more appropriate.

D. **Renal profile (D)** is related to kidney function and is not directly linked to the presented symptoms and signs, which are more related to the endocrine system.

**Core Concept:**

In medical examination, it is essential to consider the specific symptoms and signs presented by the patient while selecting the appropriate investigation. In this case, the symptoms and signs are primarily related to the endocrine system, specifically the hypothalamic-pituitary-ovarian axis.

**Why the Correct Answer is Right:**

The correct answer, **B. Prolactin level**, is essential in evaluating the patient's symptoms and signs. Elevated prolactin levels can lead to hypothalamic-pituitary-ovarian axis dysfunction, which is the likely cause of oligomenorrhea, amenorrhea, and hypertension in this case.

**Why Each Wrong Option is Incorrect:**

A. Thyroid function test (A) is not directly related to the presented symptoms and signs. Hypothyroidism can lead to oligomenorrhea, but it is less likely to