Endocrinology is the study of hormones. Hormones are bio-chemicals which help in normal metabolic functions of the body. Abnormalities in their secretion and transport from one part of the body to the other usually result in diseases.
Some of these diseases are Diabetes, Infertility, thyroidism, etc.
The investigations in this area include hormonal profiles for fertility studies, insulin testing, growth hormone tests, thyroid function test, etc.