Which hormone is not associated with stimulating hair growth?

Growth hormone is not typically associated with stimulating hair growth in the way that the other hormones listed are. Insulin, estrogen, and testosterone each play significant roles in hair health and growth. Insulin can influence hair growth by regulating blood sugar levels, which indirectly affects the availability of nutrients for hair follicles. Estrogen is known to promote hair growth, particularly in women, by prolonging the growth phase of hair follicles and maintaining hair density. Testosterone, or its derivatives, can also stimulate hair growth, especially in androgen-sensitive areas, such as on the face and body.

In contrast, while growth hormone has various physiological effects, its primary role does not include the direct stimulation of hair growth. Instead, it is more involved in overall body growth and metabolism. Therefore, growth hormone is not recognized as a key hormone that actively promotes hair growth when compared with the other hormones listed.