drugs.

That said, we have drugs for all sorts of things that would seem like miracles if introduced today.

Thyroid not working? There's a drug for that.

Pancreas not working? There's a drug for that.

Same for other hormones. Even some where the drug itself is not the hormone, but something that tells your body to make the hormone (clomid for testosterone, for example)

Anxious? drug
Depressed? drug