I'm not sure if it's the "best" example but.
If your blood tempature is low, the hypothalamus will issues reflex commands that make your body shiver. If you are hot, you will sweat is the opposite of this.
Another example is, if your blood contains pyrokines then you might have an infection so you begin to run a fever as your body's way to kill the pathogen at the direction of the hypothalamus.
Hope these examples help!
