Anorexia nervosa is an eating disorder characterized by excessive weight loss, and irrational fear of gaining weight and distorted body self-perception. Anorexia nervosa usually developes during adolescence and early adulthood.Due to the fear of gaining weight, people with this disorder restrict the amount of food they intake. This restriction of food intake causes metabolic and hormonal disorders.The terms anorexia nervosa and anorexia are often used interchangeably, however anorexia is simply a medical term for lack of appetite. Anorexia nervosa has many complicated implications and may be thought of as a lifelong illness that may never be truly cured, but only managed over time. Anorexia nervosa is characterized by low body weight, inappropriate eating and obsession with thin figure.
Anorexia nervosa is often coupled with a distorted self image which may be maintained by various cognitive biases that alter how the affected individual evaluates and thinks about her or his body, food and eating. Persons with anorexia nervosa continue to feel hunger, but deny themselves all but very small quantities of food. The average caloric intake of a person with anorexia nervosa is 600–800 calories per day, but extreme cases of complete self-starvation are known.It is a serious mental illness with a high incidence of comorbidity and similarly high mortality rates to serious psychiatric disorders.
Anorexia most often has its onset in adolescence and is most prevalent among adolescent girls. However, more recent studies show that the onset age of anorexia has decreased from an average of 13 to 17 years of age to 9 to 12. While it can affect men and women of any age, race, and socioeconomic and cultural background,Anorexia nervosa occurs in females 10 times more than in males. While anorexia nervosa is quite commonly (in lay circles) believed to be a woman ‘s illness, it should not be forgotten than ten per cent of people with anorexia nervosa are male.
In anorexia nervosa, under-nutrition and weight regulatory behaviours such as vomiting and laxative abuse can lead to a range of biochemical problems.
Characteristic Biochemistry of Picky Eaters, Anorexia Nervosa or Feeding Difficulties.
- Hypokalaemia is the most common electrolyte abnormality.
- Metabolic alkalosis occurs in patients who vomit or abuse diuretics and acidosis in those misusing laxatives.
- Hyponatraemia is often due to excessive water ingestion, but may also occur in chronic energy deprivation or diuretic misuse.
- Urea and creatinine are generally low and normal concentrations may mask dehydration or renal dysfunction.
- Abnormalities of liver enzymes are predominantly characterized by elevation of aminotransferases, which may occur before or during refeeding.
- The serum albumin is usually normal, even in severely malnourished patients.
- Amenorrhoea is due to hypogonadotrophic hypogonadism.
- Reduced concentrations of free T4 and free T3 are frequently reported and T4 is preferentially converted to reverse T3.
- Cortisol is elevated but the response to adrenocorticotrophic hormone is normal. Hypoglycaemia is common.
- Hypercholesterolaemia is a common finding but its significance for cardiovascular risk is uncertain.
- A number of micronutrient deficiencies can occur.
- Other abnormalities include hyperamylasaemia, hypercarotenaemia and elevated creatine kinase.
There is an increased prevalence of eating disorders in type 1 diabetes and the intentional omission of insulin is associated with impaired metabolic control.
- Refeeding may produce electrolyte abnormalities, hyper- and hypoglycaemia, acute thiamin depletion and fluid balance disturbance; careful biochemical monitoring and thiamin replacement are therefore essential during refeeding.
Future research should address the management of electrolyte problems, the role of leptin and micronutrients, and the possible use of biochemical markers in risk stratification.