**Question:** Refeeding syndrome is due to increased release of the following hormone:

A. Insulin
B. Glucagon
C. Growth Hormone
D. Cortisol

**Correct Answer:** .

**Core Concept:** Refeeding syndrome is a potentially life-threatening complication that occurs when a person quickly resumes eating after an extended period of starvation or malnutrition. This leads to a series of physiological disturbances affecting glucose, electrolyte, and fat homeostasis.

**Why the Correct Answer is Right:** Cortisol is a hormone secreted primarily by the adrenal glands in response to stress. In the context of refeeding syndrome, cortisol is released to promote glycogen synthesis, gluconeogenesis, and lipolysis. However, the rapid increase in cortisol levels can lead to a cascade of adverse effects, including:

1. Increased glucose production: Cortisol promotes gluconeogenesis and glycogenolysis, resulting in hyperglycemia. This can exacerbate existing hyperglycemia or lead to new-onset hyperglycemia in previously normoglycemic patients.
2. Altered electrolyte balance: Cortisol promotes potassium (K+) uptake by muscles and reduces renal K+ reabsorption, leading to hypokalemia. Additionally, it promotes magnesium (Mg2+) excretion, causing hypomagnesemia.
3. Lipid mobilization: Cortisol triggers lipolysis, leading to an increase in free fatty acids and glycerol, which can cause lactic acidosis, hypokalemia, and hypomagnesemia.

**Why Each Wrong Option is Incorrect:**

A. Insulin: Insulin is a hormone that lowers blood glucose levels by promoting glucose uptake into cells and inhibiting gluconeogenesis. It does not contribute to the pathogenesis of refeeding syndrome.

B. Glucagon: Glucagon acts as an antagonist to insulin, raising blood glucose levels by promoting glycogen synthesis and gluconeogenesis. In contrast to cortisol, glucagon would oppose the effects of refeeding syndrome.

C. Growth Hormone: Growth hormone plays a role in promoting growth and tissue repair but does not directly contribute to the adverse effects of refeeding syndrome.

D. Cortisol: As explained above, cortisol is the hormone directly associated with refeeding syndrome due to its effects on glucose, electrolyte, and lipid homeostasis.

**Clinical Pearl:** Monitoring of electrolyte levels, particularly potassium (K+) and magnesium (Mg2+), is crucial in patients at risk for refeeding syndrome, such as those with malnutrition, cachexia, or prolonged fasting. Early recognition and intervention of refeeding syndrome can prevent severe complications and improve patient outcomes.