what is the cause of increased melanin pigmentation in Addison’s disease is :
Hyperpigmentation in skin is caused by an increase in melanin, the substance in the body that is responsible for color (pigment). Certain conditions, such as pregnancy or Addison's disease (decreased function of the adrenal gland), may cause a greater production of melanin and hyperpigmentation.Exposure to sunlight is a major cause of hyperpigmentaion, and will darken already hyperpigmented areas.igmentation is the coloring of a person's skin. When a person is healthy, his or her skin will appear normal in color. In the case of illness or injury, the person's skin may change color, becoming darker (hyperpigmentation) or lighter (hypopigmentation).