**Core Concept**
Cushing syndrome is a rare endocrine disorder caused by excessive levels of cortisol in the body, leading to various systemic effects. This condition can result from either an overproduction of cortisol by the adrenal glands or an overproduction of adrenocorticotropic hormone (ACTH) by the pituitary gland.

**Why the Correct Answer is Right**
Cushing syndrome is characterized by a range of clinical features, including weight gain, particularly in the trunk and face, high blood pressure, glucose intolerance or diabetes mellitus, and a variety of skin changes such as striae, acne, and hirsutism. Additionally, individuals with Cushing syndrome may experience a range of psychological and behavioral changes, including mood swings, anxiety, and depression.

**Why Each Wrong Option is Incorrect**
**Option A:** While osteoporosis is a potential complication of long-term Cushing syndrome, it is not a defining characteristic of the disorder. Osteoporosis occurs due to the direct effects of cortisol on bone metabolism.
**Option B:** Hypokalemia is not typically associated with Cushing syndrome. Instead, Cushing syndrome may lead to hypernatremia and hypokalemia is more commonly seen in conditions like Conn's syndrome.
**Option C:** Hypothyroidism is not a characteristic of Cushing syndrome. Cushing syndrome can cause hyperglycemia and glucose intolerance, but hypothyroidism is not a typical feature.

**Clinical Pearl / High-Yield Fact**
It's essential to note that Cushing syndrome can be caused by a variety of factors, including exogenous glucocorticoid therapy, adrenal tumors, and ectopic ACTH-producing tumors. A high index of suspicion is required for early diagnosis and treatment.

**Correct Answer:** D