Cushing's disease is caused by

Options

A. Low level of GH
B. High level of thyroxine
C. Hyper-secretion of STH
D. Hyper-secretion of corticoid hormones

Answer

### Step-by-Step Solution:

1. **Understanding Cushing's Disease**: Cushing's disease is a condition that results from excessive levels of cortisol in the body. It is often associated with Cushing's syndrome, which refers to the symptoms and signs that occur due to prolonged exposure to high levels of cortisol.

2. **Identifying the Cause**: The primary cause of Cushing's disease is the hypersecretion of corticoid hormones, particularly cortisol, from the adrenal cortex. This can occur due to various factors, including tumors in the pituitary gland (which can lead to increased production of adrenocorticotropic hormone, ACTH) or tumors in the adrenal glands themselves.

3. **Evaluating the Options**:
- **Option A**: Low level of growth hormone - This is not related to Cushing's disease.
- **Option B**: High level of thyroxine - This is related to thyroid function, not cortisol levels.
- **Option C**: Hypersecretion of STH (Somatotropic Hormone) - This is related to growth hormone and does not cause Cushing's disease.
- **Option D**: Hypersecretion of corticoid hormones - This is the correct answer as it directly relates to the excess production of cortisol.

4. **Conclusion**: Based on the evaluation of the options, the correct answer is **Option D: Hypersecretion of corticoid hormones**.