Watery Diarrhoea and Fatigue

Try out this gastrointestinal case and test your clinical knowledge. The answers are at the bottom.


A 16-year-old woman presents to her GP with a 4-month history of bloating and watery, offensive diarrhoea without any blood. She also reports that she feels excessively tired and is often falling asleep in the middle of the day.

SpO2: 97%
Temperature: 36.7
BP: 110/87
HR: 69
RR: 14

Abdomen SNT
PR unremarkable
Scaly, erythematous rash on knees and elbows


Some initial bloods are taken:

Q1: Comment on the blood results

Q2: What further investigations would be useful?

She is referred to secondary care for further testing where a tissue sample is taken:


• Duodenal crypt hyperplasia
• Subtotal villous atrophy
• Intraepithelial lymphocytosis
• Lymphocyte infiltration of lamina propria


Q3: What is the diagnosis?


Q4: What complications can develop from this condition?


Reveal the Answers

Answer to Question 1

The bloods show a normocytic anaemia, with a low iron, B9 and B12. This suggests that the normocytosis is secondary to both a macrocytic and a microcytic anaemia occurring simultaneously, and thus suggests extensive disease of the small bowel as iron, B9 and B12 are absorbed in the duodenum, jejunum, and terminal ileum respectively. The normal WCC and CRP suggests that a chronic cause of infective diarrhoea e.g., giardiasis is unlikely, and the normal thyroid functions point against that being the cause of her excessive tiredness.

Answer to Question 2

The main differentials in this patient are:

• Inflammatory bowel disease
• Infection (gastroenteritis)
• Coeliac’s disease


• Stool sample with microscopy and culture – excludes infective causes
• Faecal calprotectin – useful as an aid to diagnosing inflammatory bowel disease e.g., Crohn’s
• Faecal elastase – can suggest if there is any pancreatic insufficiency e.g. from undiagnosed CF
• Faecal immunohistochemistry testing – can detect microscopic bleeding from the GI tract


• p-ANCA antibodies – often positive in UC
• ASCA antibodies – often positive in Crohn’s
• Total IgA – Required for diagnosing coeliac’s as they can exclude an IgA deficiency
• IgA anti-TTG – Antibody found in coeliac’s disease
• IgA anti-endomysial antibodies – Antibody found in coeliac’s disease
• IgA anti- gliadin antibodies – Antibody found in coeliac’s disease

Special tests

• Duodenal biopsy would highlight small bowel disease and is the gold standard investigation in this case

Answer to Question 3

The histology findings coupled with the classic extensor-surface rash (dermatitis herpetiform) points to a diagnosis of coeliac’s disease.

Answer to Question 4

Long term complications include:

• Chronic anaemia, leading to subacute degeneration of the cord if B12 is not replenished
• Predisposition to other autoimmune conditions e.g. T1DM, Hashimoto’s
• Malnutrition due to malabsorption
• Lactose intolerance
• Osteoporosis due to lack of calcium absorption
• Enteropathy associated T-cell lymphoma (EATL) – a condition where a T-cell lymphoma can arise in the wall of the small bowel and cause bowel obstruction due to the chronic inflammation caused by coeliac’s
• Neurological sequelae including degeneration of cerebellum leading to ataxia

To get more information about the conditions mentioned in this case including diagnosis and management, have a look at our free haematology notes on In2Med. Written by medical students, we have pitched them just at the right level to help you ace your exams.

Dr Amol Joshi
University of Cambridge

About The Author

This case is written by Dr Amol Joshi who has an interest in writing medical puzzles.