Which hormone suppresses the immune system during stress and influences various metabolic processes?

• A. Thyroxine
• B. Estrogen
• C. Cortisol
• D. Progesterone

Answer: (C)

When the body faces stress, the hypothalamus triggers the pituitary to release ACTH, which prompts the adrenal cortex to secrete cortisol. This hormone helps keep energy available by promoting glucose production, protein breakdown, and fat mobilization. It also plays a key role in dampening the immune response by inhibiting inflammatory cytokines and reducing immune cell activity, which helps prevent excessive inflammation during stress, though prolonged cortisol elevation can impair immune defense. Among the options, cortisol is the hormone most closely linked to stress-related immunosuppression and broad metabolic regulation, making it the best fit. The other hormones are involved in metabolism or reproductive signaling but do not primarily serve this stress-immunity role.