Malnutrition including anorexia nervosa

What is malnutrition?

Malnutrition occurs when the supply of nutrients and energy is inadequate to meet the body's requirements.

What causes malnutrition?

Worldwide, the most common cause of malnutrition is an inadequate food supply. Gastrointestinal infections, particularly parasitic infections, exacerbate this problem. Preschool-aged children in developing countries are most at risk because of their increased protein and energy requirements, greater susceptibility to infection, and exposure to unhygienic conditions. Protein-energy malnutrition occurs mainly in young children from developing countries at the time of weaning.

In developed countries, other causes of malnutrition are more prominent:

• Reduced absorption or abnormal metabolism of nutrients and energy due to illnesses such as inflammatory bowel disease (e.g. Crohn disease), gastrointestinal infections, cystic fibrosis, extensive thermal burns, or cancer.
• Insufficient food intake e.g. anorexia nervosa.
• Complex social and medical problems – for example, elderly people can become malnourished due to a combination of reduced appetite, impaired mental functioning, medications, coexisting illnesses, psychosocial isolation, heavy alcohol intake, and/or depression.
• Inadequate food supply can also be a problem in low-income areas of developed countries.

Dermatological features of malnutrition

Although malnutrition affects almost every organ in the body, this page focuses on the dermatological features.

When malnutrition is caused by anorexia nervosa, a number of specific dermatological features are seen:

Skin changes associated with anorexia nervosa become more frequent when the body mass index (BMI) falls to 16 kg/m2 or less. Patients with bulimia nervosa (and some patients with anorexia nervosa) engage in uncontrollable binge-eating episodes, followed by purging behaviours such as self-induced vomiting or the use of laxatives. Dermatological features associated with purging behaviours include:

• Calluses over the knuckles (also called Russell sign) caused by repeated rubbing of the skin against the upper front teeth when the hand is used to induce vomiting.
• Erosion of dental enamel and tooth loss due to vomiting.
• Post-vomiting facial petechiae – tiny red, purple, or brown spots due to breakage of small blood vessels and bleeding into the skin.
• Post-vomiting subconjunctival haemorrhage – red eye/s due to damage to small blood vessels in the eyes.
• Adverse reactions to drugs such as laxatives, diuretics, and appetite suppressants e.g. thiazide diuretics may induce drug photosensitivity.

Diagnosis of malnutrition

• Progressive weight loss; children may have poor growth.
• Blood tests may reveal low levels of protein; electrolyte imbalances (abnormal levels of salts in the blood); and evidence of iron deficiency or vitamin deficiencies.

What is the treatment for malnutrition?

In patients with severe malnutrition, fluid and electrolyte imbalances should be corrected first. Food should be introduced slowly and carefully. Vitamin and mineral supplements may be needed. The skin changes associated with malnutrition generally resolve when nutritional deficiencies are corrected and the patient gains weight.