Final answer:
Gian-Carlo may need cortisol supplementation after surgery to remove part of his adrenal cortex, as the adrenal cortex produces corticosteroids vital for stress response and metabolism.
Step-by-step explanation:
After Gian-Carlo has part of his adrenal cortex removed because of a tumor, he may need supplementation with cortisol. This is because the adrenal cortex is responsible for producing corticosteroids like cortisol, which play a vital role in regulating metabolism, reducing inflammation, and helping the body respond to stress. If part of the adrenal cortex is removed, the production of cortisol may not meet the body's needs, hence the requirement for supplementation. Melatonin is associated with the sleep-wake cycle and is produced by the pineal gland, insulin is produced by the pancreas, oxytocin is a hormone that triggers childbirth and lactation, and calcitonin is involved in calcium homeostasis and is produced by the thyroid gland. Since none of these other hormones are produced by the adrenal cortex, they would not typically be needed as a result of adrenal cortex surgery.