Ellen Baxter an 18-year-old female law student, presents to outpatient clinic with her mother with 2-year history of weight loss, amenorrhoea, and occasional ‘diarrhoea’
History reveals no red flag symptoms, other than gradual weight loss and increasing exercise over the last 2 years, with a previous history of laxative abuse as a teenager. She admits she still takes laxatives regularly, as she feels constipated, although she has watery diarrhoea intermittently. She admits she regularly ‘skips’ meals. She has not menstruated for at least 2 years.
On examination, she was anxious and her mood is guarded in affect. Her Body Mass Index (BMI) is 12 kg/m2, appeared dry and malnourished with widespread lanugo hair. There is some mild peripheral oedema. She is bradycardiac (Pulse 40 bpm), but there were no other external examination findings. PR examination shows solid stool in the rectum.
Initial blood tests showed a low potassium (2.9 mmol/L), low phosphate (0.65 mmol/L), low random glucose (3.5 mmol/L), borderline-low albumin (33 g/dL), with liver function tests showing a mild transaminitis.
Question 1: What is your differential diagnosis?
A. Coeliac Disease
B. Inflammatory Bowel Disease
C. Anorexia Nervosa
D. GI Malignancy
E. Bile Salt Malabsorption
CORRECT ANSWER: C
This patient clearly has a diagnosis of anorexia nervosa with an extremely low BMI. This is consistent with the history of laxative abuse, excess exercise and admission by the patient that she restricts her calorie intake. The diarrhoea described appears to be overflow diarrhoea associated with chronic laxative abuse. She has secondary amenorrhoea due to her low BMI. The differential diagnosis is limited given the findings, but in the absence of key components in the history (laxative abuse, calorie restriction) and more definite history of chronic diarrhoea, the presence of anaemia, one may consider excluding organic causes such as coeliac disease and inflammatory bowel disease, or other causes of malabsorption. There are no ‘red’ flag symptoms (including rapid weight loss, night sweats, ‘B symptoms’ (consistent with a haematological malignancy) or any other GI symptoms such as dysphagia, PR bleeding). There is no history of previous GI surgery (such as a right hemicolectomy) leading to diarrhoea via bile salt malabsorption – furthermore you would not expect any of the other features seen in this patient with this condition.
Q2. What is your initial management?
Question setter & Expert: Dr Phillip Smith, Gastroenterology SpR & BSG Trainees Chair
For tips on following hashtags read more, and try one of our recommended Twitter plugins.