How can you tell if your dhydrated, or can you be dhydrated from loosing a lot of blood?

Desire to drink: Dehydration is a condition of loss of body water. Anemia is a condition of loss of body blood. The body responds to dehydration with a sense of thirst. Your mouth feels dry, lips crack, skin is dry and stiff, and no urine output. Anemia causes a sense of weakness, pale appearance, and light headed when standing. Acute blood loss can lower blood pressure and cause poor function of the brain.