Hormonal changes due to anorexia nervosa and their effects on bone remodeling during adolescence
Miedema, Lorraine Elizabeth
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Anorexia nervosa is a disease that afflicts a large portion of the adolescent population. Anorexia is clinically characterized by a very low weight for the adolescent's height and age, an extreme fear of gaining weight, a distorted body image, and amenorrhea. When anorexia is acquired during adolescence, specifically before or during puberty, a negative affect is observed in bones, which are peaking in their remodeling process to create more bone mass. This negative outcome is the result of altered hormone levels that regulate normal bone. This thesis aimed to review the literature on how anorexia affects bone growth and development and to discuss the current therapies available to remedy these effects. This study evaluated a vast amount of literature assessing the negative effects of anorexia nervosa on adolescent hormones and further evaluated how these hormonal changes affect bone in the pubertal adolescent. Research found that an individual with anorexia will have low levels of leptin and estrogen. They will also have high levels of cortisol and ghrelin. There is a high level of growth hormone, but low levels of insulin like growth factor 1 conferring a resistance to growth hormone. Each of these hormones plays a role in the bone remodeling process. Leptin, growth hormone, and insulin like growth factor normally stimulate osteoblast formation or activity. With a decrease in leptin and insulin like growth factor and a resistance to growth hormone, there is a subsequent decrease in osteoblastic activity. Estrogen is known to decrease bone resorption markers through the increase in apoptosis of osteoclasts and decreasing osteoblast apoptosis. With a decrease in the estrogen level, the osteoclast population increases and osteoblasts decrease in number. High cortisol levels are associated with impaired bone growth and increased bone resorption markers whereas ghrelin levels correlate inversely with bone turnover markers. Since ghrelin levels are high in anorexia, there is less bone turnover. These hormonal alterations decrease the bone mineral density in pubertal adolescent leading to an increase in fractures; additionally, if the disease progresses long enough, osteopenia or osteoporosis can ensue. There are many ways to combat the bone issues associated with anorexia and to help repair the many issues surrounding it. Ultimately, the best way to increase the bone health of the adolescent is through weight gain. There are also hormone replacement therapies aimed at correcting hormones levels as well as drugs aimed at improving the negative thoughts and compounded effects of an anorexic's psyche. Other psychological therapies include group therapy, cognitive-behavior therapy, and nutritional counseling. A long term solution to this primarily adolescent disorder requires considerable changes socially in addition to medical and psychological therapies. The media's portrayal of the beauty standard must be radically altered in order to change how youth perceive themselves. Additionally, educational awareness must be raised in middle and high school curriculums to help adolescent's combat anorexia. These changes must be varied and can be in the form of media (commercials, social, written, online), better advocacy (celebrities for healthier lifestyles) and education (through schools). Without changing the perceptions of beauty in the media first, anorexia nervosa will remain prevalent because adolescents will have no other role model to try to emulate.
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