A 25-year-old woman comes to the physician complaining of chronic fatigue, muscle weakness, and a noticeable decrease in her exercise tolerance over the past six months. She reports no significant past medical history. Physical examination reveals low blood pressure and hyperpigmentation of her skin, especially in her joints and oral mucosa. Lab tests show hyponatremia, hyperkalemia, and metabolic acidosis. Her ACTH levels are significantly elevated. Based on her symptoms and lab results, which of the following hormone deficiencies is most likely responsible for her condition?
The patient's symptoms and lab results are consistent with Addison's disease, which is characterized by a deficiency in cortisol and aldosterone due to damage of the adrenal cortex. Aldosterone is a hormone that helps regulate sodium and potassium balance, as well as blood pressure. The deficiency of aldosterone in Addison's disease can lead to hyponatremia, hyperkalemia, and low blood pressure - all of which are seen in this patient. The hyperpigmentation is due to the increased ACTH levels, as the pituitary gland tries to stimulate the damaged adrenals to produce more hormones. The high ACTH also stimulates melanocytes, leading to hyperpigmentation. Cortisol deficiency also occurs in Addison's disease, but it primarily leads to symptoms such as fatigue, low blood sugar, and poor stress response, rather than the specific electrolyte imbalances and hyperpigmentation seen here.