Hyperpigmentation of skin with cortisol deficiency
Mammals and humans have melanocytes. These have granules responsible for skin color. Melanocytes have melanotropin-1 receptors.
Melanotropins α- and β-MSH do not circulate in human adults, although they are produced in pituitary, and their function in humans is unknown. ACTH is mainly responsible for skin color, which acts in the skin via melanocyte receptors.
In the presence of primary cortisol deficiency, i.e adrenal deficiency ACTH levels are increased. This increased ACTH is responsible for hyperpigmentation in these patients. in secondary cortisol deficiency i.e pituitary hypofunction, ACTH is not increased so hyperpigmentation does not occur.