Hot flushes are observed due to deficiency of –
**Core Concept**
Hot flushes, also known as hot flashes, are a common symptom experienced by women during menopause or as a side effect of certain medications. The underlying mechanism involves the hypothalamic thermoregulatory center, which is influenced by estrogen levels. Decreased estrogen levels lead to an imbalance in the hypothalamic-pituitary-adrenal axis, resulting in vasodilation and increased blood flow to the skin.
**Why the Correct Answer is Right**
Estrogen plays a crucial role in regulating the body's thermoregulatory response. In women, estrogen receptors are present in the hypothalamus, which helps maintain normal body temperature. When estrogen levels decrease, the hypothalamus becomes less sensitive to temperature changes, leading to an inappropriate vasodilatory response, characterized by hot flushes. This is often seen in postmenopausal women or in those undergoing hormone replacement therapy (HRT) with estrogen deprivation.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because hot flushes are not primarily associated with a deficiency of dopamine. While dopamine can influence various physiological processes, it is not directly linked to the thermoregulatory response.
**Option B:** This option is incorrect because hot flushes are not typically associated with a deficiency of serotonin. Although serotonin can affect mood and other physiological processes, it is not directly involved in the pathophysiology of hot flushes.
**Option C:** This option is incorrect because hot flushes are not primarily associated with a deficiency of thyroid hormone. While thyroid hormone can influence metabolism and body temperature, it is not directly linked to the thermoregulatory response seen in hot flushes.
**Clinical Pearl / High-Yield Fact**
A classic exam trap is to confuse hot flushes with night sweats, which can be caused by various factors, including infections, malignancies, and medication side effects. However, hot flushes are typically associated with estrogen deficiency and are more common in women during menopause or hormone replacement therapy.
**Correct Answer: D. Estrogen**