**Question:** All are causes of amenorrhoea EXCEPT:

A. Hypothyroidism
B. Ovarian failure due to menopause
C. Anemia
D. Oral contraceptive pill intake

**Core Concept:** Amenorrhea is the medical condition where a woman does not experience a menstrual period. This can be primary (no menstruation ever) or secondary (previously present menstruation that has stopped). Understanding the various causes of amenorrhea is essential for appropriate diagnosis and management.

**Why the Correct Answer is Right:** Hypothyroidism (low thyroid hormone levels) is a cause of primary amenorrhea, as it affects the development and functioning of the ovaries, pituitary gland, and hypothalamus, leading to impaired gonadotropin secretion and menstruation cessation.

**Why Each Wrong Option is Incorrect:**

- Ovarian failure due to menopause (option B) typically occurs in postmenopausal women, not premenopausal females.
- Anemia (option C) can cause secondary amenorrhea, but not primary amenorrhea as it affects the hypothalamic-pituitary-ovarian axis.
- Oral contraceptive pill intake (option D) is a common cause of secondary amenorrhea, as it suppresses gonadotropin secretion and thereby follicle development and ovulation.

**Why the Correct Answer is Right:** While hypothyroidism can lead to amenorrhea, it is less common in premenopausal women and does not directly affect the hypothalamic-pituitary-ovarian axis.

**Why Each Wrong Option is Incorrect:**

- Ovarian failure due to menopause (option B) is typically seen in postmenopausal women, not premenopausal females.
- Anemia (option C) can cause secondary amenorrhea but not primary amenorrhea, as it affects the hypothalamic-pituitary-ovarian axis.
- Oral contraceptive pill intake (option D) is a common cause of secondary amenorrhea as it directly suppresses gonadotropin secretion and follicle development and ovulation.

**Core Concept:** Amenorrhea can be caused by various factors, including hormonal imbalances, anatomical abnormalities, and medical conditions. Understanding the distinct causes of primary and secondary amenorrhea is crucial for accurate diagnosis and management.