Does an increase in osmotic pressure lead to an increase or decrease in urine output?

Under normal circumstances, an increase in osmotic pressure leads to decreased urine output in patients. This occurs because elevated osmotic pressure raises the concentration of other substances in plasma, thereby enhancing water reabsorption within the body and reducing the volume of water reaching the glomeruli—resulting in oliguria. Most commonly, increased osmotic pressure is caused by dehydration. Common causes of dehydration include inability to eat normally due to injury or extensive burn injuries leading to significant fluid loss, both of which can trigger an elevation in osmotic pressure.