10/09/2026
The endocrine system coordinates a body’s internal metabolic energy level, reproduction, growth and development. Hormones generated by this system strongly affect hair follicle structure, hair growth cycle and density. As a result, physical conditions that affect the endocrine system, for example, PMOS/PCOS, can strongly influence hair growth and cycling alterations. These are the key hormones:
+ Androgens (the primary regulators of hair growth in humans)
+ Oestrogens (together, estrogen & progesterone both increase sexual hair growth in puberty and inhibit hair growth in menopause)
+ Growth Hormone (affects sexual hair growth)
+ Insulin and Insulin-Like Growth Factor (IGF) (with androgens, affect hair development stimulation)
+ Prolactin (hair development)
+ Cortisol (hair follicle activity)
+ Melatonin (affects hair pigmentation & growth)
+ Thyroid Hormone (together, thyroxine/T3 & triiodothyronine/T4 affect hair cycle frequency)