Patients with both Graves’ disease and Cushing syndrome are overproducing hormones that have which one of the following in common?
**Core Concept**
Graves' disease is an autoimmune disorder characterized by the overproduction of thyroid hormones, primarily triiodothyronine (T3) and thyroxine (T4), due to the stimulation of the thyroid gland by thyroid-stimulating immunoglobulins (TSI). Cushing syndrome, on the other hand, is caused by an excess of cortisol, often due to an adrenocorticotropic hormone (ACTH)-producing pituitary tumor. Both conditions involve the overproduction of hormones that have a significant impact on the body's metabolic state.
**Why the Correct Answer is Right**
The common feature between the hormones overproduced in Graves' disease and Cushing syndrome is their ability to induce gluconeogenesis and glycogenolysis. This results in increased glucose production and release into the bloodstream, leading to hyperglycemia. The increased levels of cortisol and thyroid hormones stimulate the enzyme glucose-6-phosphatase, which converts glucose-6-phosphate into glucose. This process is essential for maintaining blood glucose levels during fasting periods. Additionally, both hormones increase the activity of phosphoenolpyruvate carboxykinase (PEPCK), a key enzyme involved in gluconeogenesis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the hormones overproduced in Graves' disease and Cushing syndrome do not primarily affect the immune system. While thyroid hormones have some immunomodulatory effects, the primary issue in Graves' disease is the overproduction of thyroid hormones, not an immune response.
**Option B:** This option is incorrect because the hormones overproduced in Graves' disease and Cushing syndrome do not primarily cause vasoconstriction. While cortisol has some vasoconstrictive effects, the primary issue in Cushing syndrome is the excess of cortisol, not its vasoconstrictive effects.
**Option C:** This option is incorrect because the hormones overproduced in Graves' disease and Cushing syndrome do not primarily affect the nervous system. While thyroid hormones have some effects on the nervous system, the primary issue in Graves' disease is the overproduction of thyroid hormones, not their effects on the nervous system.
**Option D:** This option is incorrect because the hormones overproduced in Graves' disease and Cushing syndrome do not primarily cause inflammation. While cortisol has some anti-inflammatory effects, the primary issue in Cushing syndrome is the excess of cortisol, not its anti-inflammatory effects.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that both Graves' disease and Cushing syndrome can cause glucose intolerance and hyperglycemia due to the increased production of glucose-6-phosphatase and PEPCK. This is a critical aspect of their pathophysiology and can have significant implications for patient management.
**Correct Answer: C. Increased gluconeogenesis and glycogenolysis.**