Persistent and chronic diarrhoea — structured clinical encounter

Station brief (candidate)

You are the paediatric registrar in a general paediatric clinic. A nine-year-old is referred with a six-month history of three to five loose, pale, bulky stools a day, a distended abdomen, tiredness and irritability, and a fall from the 50th to below the 9th centile for weight over the past year. The general practitioner has found a microcytic anaemia. The team asks you to establish the differential and the workup, to explain a serology pitfall, and then to proceed to the management and family counselling. You have 12 minutes with the team and 5 minutes for examiner discussion. [1]

Information available on request

• Nine years old, previously well; loose pale bulky stools for six months; no overt blood in the stool. [1]
• Distended abdomen, wasted buttocks, pallor, irritability; growth chart shows a fall across two centiles for weight. [6]
• Diet: normal gluten-containing diet; no excessive juice intake; family history of a maternal aunt with coeliac disease. [6]
• Bloods (on request): microcytic anaemia, low ferritin, low folate, normal C-reactive protein, normal albumin. [1]
• Faecal calprotectin (on request): normal; stool culture and Giardia antigen negative. [7]
• Coeliac serology (on request): immunoglobulin A anti-tissue-transglutaminase at 12 times the upper limit of normal, positive endomysial antibody on a separate sample, normal total immunoglobulin A. [6]

Tasks

1. Give the differential and identify the features that make this organic rather than functional diarrhoea. Grade the priority of your differential. [1]
2. Outline the stool-directed and serological workup, and state what the normal faecal calprotectin and the coeliac serology tell you. [7]
3. A colleague suggests starting a gluten-free diet immediately and checking the coeliac antibodies in a month. Explain why this is wrong. [6]
4. State the diagnosis you can now make and how the ESPGHAN 2020 criteria apply to this child. [6]
5. Outline the management and counsel the family on the outlook. [6]

Marking anchors

Must-hit

• Recognises this as organic diarrhoea from the pale bulky steatorrhoeic stool, the distended abdomen with wasted buttocks, the iron and folate deficiency and the fall across two growth centiles, and puts coeliac disease at the top of the differential with inflammatory bowel disease and giardiasis considered and reasonably excluded by the normal calprotectin, normal inflammatory markers and negative stool studies. [1] [7]
• Explains that coeliac serology (immunoglobulin A anti-tissue-transglutaminase with a total immunoglobulin A) must be taken while the child is still eating gluten, because a gluten-free diet normalises the antibodies within weeks and makes the diagnosis impossible to confirm without a formal gluten challenge. [6]
• Applies the ESPGHAN 2020 no-biopsy pathway correctly: in this symptomatic child with an anti-transglutaminase titre at or above ten times the upper limit of normal and a positive endomysial antibody on a separate sample, with normal total immunoglobulin A, coeliac disease can be diagnosed without duodenal biopsy. [6]

Merit

• States that management is a strict lifelong gluten-free diet with dietitian support, correction of the iron and folate deficiency, and monitoring of falling antibody titres and catch-up growth, and counsels the family that the outlook is excellent with dietary adherence. [6]

Fail

• Starts a gluten-free diet before the serology is taken, or accepts a negative serology taken after gluten withdrawal, thereby making the diagnosis unconfirmable. [6]
• Mislabels the child as having toddler's diarrhoea or a functional disorder despite the steatorrhoea, the anaemia and the faltering growth, and fails to investigate. [4]