A 50-year-old woman presents with symptoms of weakness and hyperpigmentation. What condition is likely?

The presentation of weakness and hyperpigmentation in a 50-year-old woman is indicative of Addison's disease, also known as primary adrenal insufficiency. This condition occurs due to the inadequate production of adrenal hormones, including cortisol and aldosterone, often resulting from autoimmune destruction of the adrenal cortex.

Hyperpigmentation specifically is a key feature of Addison's disease, as increased melanocyte-stimulating hormone (MSH) is produced in response to low cortisol levels. The lack of cortisol leads to an increased release of adrenocorticotropic hormone (ACTH) from the pituitary gland, which stimulates the production of melanin, causing the characteristic darkened skin appearance, particularly in areas exposed to friction such as elbows, knuckles, and scars.

Weakness is another prominent symptom due to the lack of cortisol, which plays a critical role in energy metabolism and stress response. The combination of these symptoms, along with other potential findings like low blood pressure and electrolyte imbalances, strongly supports a diagnosis of Addison’s disease in this context.

The other conditions presented do not adequately explain both symptoms. Cushing's disease typically manifests with symptoms such as weight gain, round face, and hypertension rather than hyperpigmentation due to excess cortisol. Metabolic syndrome