Answers

Short answers

1 Russell’s sign, after Gerald Russell. It is seen in bulimia nervosa, which Russell described in 1979, and in the bulimic subtype of anorexia nervosa. Abrasions on the dorsum of the hand result from using the fingers to induce vomiting.

2 Hypokalaemia is virtually pathognomonic of vomiting in patients with eating disorders, and it may be reflected on electrocardiography as flattening of the T wave.

3 The treatments endorsed by the National Institute for Health and Clinical Excellence (NICE) in 2004 for bulimia nervosa are a version of cognitive behavioural therapy specifically adapted for this disease, a specific version of interpersonal psychotherapy, or high dose antidepressants (usually fluoxetine 60 mg daily).

Long answers
1 The sign and the diagnosis
Russell’s sign, after Gerald Russell, professor at the Institute of Psychiatry at the Maudsley Hospital, London. He set up an eating disorders unit at this hospital, which is now named after him.

Russell noted this sign in association with the eating disorder bulimia nervosa, which he described in 1979 as "an ominous variant of anorexia nervosa."¹ It is also seen in the bulimic subtype of anorexia nervosa, in which the low weight patient binges and purges. The presence of the abrasions or callouses on the dorsum of the hand (usually the knuckle) result from the patient using the fingers to irritate the back of the mouth to induce vomiting—the incisor teeth and mouth acids cause skin irritation. Not all patients who vomit use their hands, however, some use objects such as a toothbrush or spoon, whereas some learn to induce vomiting by exerting control over their sphincter. Some patients use other methods to get rid of calories such as laxatives, deliberate exercise and activity, or chewing and spitting out.

2 Abnormalities
Hypokalaemia is virtually pathognomic of vomiting in patients with eating disorders. This may be reflected on electrocardiography as flattening of the T wave. A "U wave" may appear, which increases in amplitude until ultimately it overtakes the T wave; it may even be impossible to distinguish between the two types of waves. The changes seen on electrocardiography in hypomagnesaemia are identical to those of hypokalaemia, and this ion is at least as important for cardiac function as potassium. It is important to be aware that oscillations in serum potassium may be as detrimental as the gradual steady decline in potassium seen in bulimia nervosa.

3 Management
The skin may be treated with urea based creams or ointments. Bulimia nervosa responds to a version of cognitive behavioural therapy specifically adapted for this disease—this is the first choice of treatment if it is available and well tolerated. Alternatively, a specific version of interpersonal psychotherapy or high dose antidepressants (usually fluoxetine 60 mg daily) may be used.^{2 3 4} Low potassium concentrations are best monitored conservatively or treated with oral rather than intravenous potassium because sudden shifts in potassium may be more harmful than stable low values. If acute intervention is considered desirable, the balance of ions should be considered and monitored using electrocardiography.

Cite this as: BMJ 2009;338:b980