Which of the following is a common symptom of Addison's Disease?

Hyperpigmentation is a hallmark symptom of Addison's Disease. This condition is characterized by adrenal insufficiency, particularly a deficiency in cortisol. The resulting hormonal imbalance leads to an increased production of adrenocorticotropic hormone (ACTH). Since ACTH is structurally similar to melanocyte-stimulating hormone (MSH), an increase in ACTH can lead to an increase in melanin production in the skin, resulting in hyperpigmentation. This can often be seen in areas that are exposed to friction or sun, as well as in mucous membranes.

Other symptoms of Addison's Disease may include fatigue, weight loss, low blood pressure, and electrolyte imbalances, but hyperpigmentation specifically is significant because it is a direct result of hormonal changes associated with the condition. In contrast, weight gain, increased blood pressure, and excessive sweating are more commonly associated with other adrenal disorders, such as Cushing's syndrome, rather than Addison's disease.