Scratching and fasting: a study of pruritus and anorexia nervosa.

An association between pruritus and eating disorders has been suggested. This study examined changes in pruritus during weight restoration in a homogeneous group of women with severe anorexia nervosa (n = 19), using a structured questionnaire, visual analogue scale, clinical examination and a range of serological markers. We demonstrated that itching is a clinical feature of anorexia nervosa, associated with low weight and resolving on weight restoration. Some 58% of the sample suffered pruritus at low weight in a stable hospital environment. There was a significant association between changes in body mass index and severity of pruritus (P = 0.033), with reduced itching on weight restoration. Pruritus occurred in the absence of abnormalities in thyroid, renal and hepatic function, serum androgens, oedema, dermatoses or compulsive washing. Scratching was manifest as 'scratch prurigo' in five cases. Where itching was present, it was experienced as severe. We discuss a variety of possible explanations, including psychopathology, endocrine factors, regional blood flow variation, eczema and the role of central opioid and serotonergic activity. We argue that anorexia nervosa should be considered in all patients at low weight presenting with pruritus, and pruritus should be considered to be a physical symptom of anorexia nervosa.