The hormones and control mechanisms that regulate sexual development, sexual function, and reproduction are referred to as reproductive endocrinology. The study of diseases and secretory status of the endocrine glands involved in reproduction, as well as their secretory products, reproductive hormones, is included in clinical reproductive endocrinology. A reproductive endocrinologist, sometimes referred to as a RE, is an obstetrician/gynecologist (OB/GYN) physician who diagnoses and treats endocrine disorders which are either relevant to reproduction. Quantifying specific hormones is required to gain a complete understanding of the complicated endocrinological activities that occur during normal and pathological reproductive function. The endocrine system is the body's best-understood humoral regulatory mechanism.