The following are hormones that maintains fluids and electrolytes, EXCEPT: aAldosterone bCalcitonin cThyroid & Parathyroid hormone dAntidiuretic hormone

To determine which hormone does not maintain fluids and electrolytes, we need to analyze each option:

a) Aldosterone: Aldosterone is a hormone produced by the adrenal glands that plays a crucial role in regulating the balance of fluids and electrolytes in the body. It promotes the reabsorption of sodium and the excretion of potassium in the kidneys, helping to maintain fluid and electrolyte balance. Therefore, aldosterone is involved in maintaining fluids and electrolytes.

b) Calcitonin: Calcitonin is a hormone produced by the thyroid gland. Its main function is to regulate calcium levels in the blood by inhibiting the release of calcium from bones. While it does not directly maintain fluids and electrolytes, it indirectly affects calcium levels, which can have an impact on electrolyte balance. However, it is not primarily responsible for maintaining fluids and electrolytes.

c) Thyroid & Parathyroid hormone: The thyroid and parathyroid hormones, including thyroxine (T4), triiodothyronine (T3), and parathyroid hormone (PTH), are involved in various physiological processes in the body. However, their primary functions are not related to maintaining fluids and electrolytes. Thyroid hormones regulate metabolism, while parathyroid hormone regulates calcium and phosphate levels in the blood.

d) Antidiuretic hormone (ADH): Antidiuretic hormone, also known as vasopressin, is produced by the hypothalamus and released by the pituitary gland. Its main function is to regulate water balance in the body by increasing water reabsorption in the kidneys. ADH helps to prevent excessive water loss and maintain fluid balance, making it directly involved in maintaining fluids and electrolytes.

Based on the above analysis, the hormone that does not maintain fluids and electrolytes is option b) Calcitonin.