Which hormone is primarily involved in fluid retention during stress?

• A. Aldosterone
• B. Insulin
• C. Glucagon
• D. Thyroxine

Answer: (A)

Aldosterone is the hormone primarily involved in fluid retention during stress. Produced by the adrenal glands, aldosterone plays a crucial role in regulating sodium and potassium levels, as well as water balance in the body. Under stress conditions, such as physical exertion or psychological stress, the body needs to maintain blood pressure and fluid balance. Aldosterone promotes the reabsorption of sodium in the kidneys, which in turn leads to water retention. This mechanism helps to increase blood volume and maintain blood pressure during stressful situations.

The role of aldosterone is particularly important in the body's response to the renin-angiotensin-aldosterone system (RAAS), which is activated in response to low blood pressure or low blood volume. This system aids in conserving fluids and electrolytes, allowing the body to cope with stress more effectively.

Other hormones like insulin, glucagon, and thyroxine have different primary functions related to metabolism and energy regulation, rather than directly influencing fluid retention during stress. Insulin facilitates glucose uptake, glucagon promotes glycogen breakdown for energy, and thyroxine primarily regulates metabolism and energy expenditure. Therefore, the primary function of fluid retention during stress is best attributed to aldosterone.