Volume of urine is regulated by

Vasopressin (ADH) acts mainly at the kidney and stimulates reabsorption of water and electrolytes by the distal tubules and thereby reduces loss of water through urine (diuresis).

Aldosterone acts mainly at the renal tubules and stimulates the reabsorption of ${\mathrm{Na}}^{+}$ and water and excretion of ${\mathrm{K}}^{+}$ and phosphate ions. Thus, it leads to excretion of concentrated urine.