Decreased synthesis of thyroxine in adults leads to a disorder characterized by decrease in basal metabolic rate, increase in body weight and oedema is

Options

A. hypothroidism
B. simple goitre
C. myxoedema
D. cretinism

Explanation

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for a disorder in adults that results from decreased synthesis of thyroxine, characterized by a decrease in basal metabolic rate, an increase in body weight, and edema.

2. **Identifying Thyroxine's Role**: Thyroxine (T4) is a hormone produced by the thyroid gland that regulates metabolism. A decrease in thyroxine leads to a lower metabolic rate, which can cause weight gain and other symptoms.

3. **Recognizing Symptoms**: The symptoms mentioned in the question are:
- Decreased basal metabolic rate (BMR)
- Increased body weight
- Edema (swelling due to fluid retention)

4. **Linking Symptoms to Disorders**: The symptoms of decreased BMR, weight gain, and edema are indicative of a specific thyroid-related disorder.

5. **Identifying the Disorder**: The disorder characterized by these symptoms in adults due to decreased thyroxine synthesis is known as **myxedema**. Myxedema is a severe form of hypothyroidism in adults.

6. **Additional Information**: Myxedema can also be referred to as **Gull's disease**. It is treated by administering thyroxine from external sources to restore normal hormone levels.

### Final Answer:
The disorder characterized by decreased synthesis of thyroxine in adults, leading to decreased basal metabolic rate, increased body weight, and edema is **myxedema** (also known as Gull's disease).

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