Corticosterone is a glucocorticoid secreted by the adrenal cortex in response to stress. Glucocorticoids are also essential for proper metabolism of fats, proteins, and carbohydrates in the body. While cortisol and corticosterone are both produced in response to stress in humans, corticosterone is the predominant glucocorticoid produced in mice and rats. Conditions such as starvation, rapid temperature change, or changes in daily routine can cause increased corticosterone levels in laboratory mice and rats. Corticosterone has also been used as a predictor of stress in a variety of wild animals.