Coeliac disease — formative SAQs

SAQ 1 — The school-age child with refractory iron-deficiency anaemia (20 marks, ~15 minutes)

A nine-year-old girl is referred with a six-month history of tiredness and pallor. Her full blood count shows a microcytic anaemia with a haemoglobin of 92 grams per litre that has not corrected despite three months of oral iron. She has also fallen from the fiftieth to the ninth centile for height, has intermittent abdominal bloating, and her maternal aunt has coeliac disease. She eats a normal gluten-containing diet. [1]

Questions

1. Give the most likely diagnosis and the three features of this history that support it. (5 marks) [2]
2. Outline the serological workup and explain why a total immunoglobulin A must accompany the first test. (5 marks) [3]
3. State the ESPGHAN 2020 criteria that allow a diagnosis of coeliac disease without a duodenal biopsy. (4 marks) [1]
4. A colleague suggests starting a gluten-free diet now and checking the antibodies in a month. Explain why this is wrong. (3 marks) [1]
5. Outline the management and counsel the family on the outlook. (3 marks) [5]

Model answer (must-hit)

1. The most likely diagnosis is coeliac disease. The three supporting features are the refractory iron-deficiency anaemia that has not responded to oral iron, because iron is absorbed at the duodenal tip where the atrophy is worst; the fall across the height centiles consistent with coeliac short stature; and the family history of an affected first-degree relative, which carries around a ten per cent risk, alongside the abdominal bloating. [2]
2. The workup is immunoglobulin A anti-tissue-transglutaminase antibody paired with a total serum immunoglobulin A, taken while she is still eating gluten. The total immunoglobulin A is required because selective immunoglobulin A deficiency occurs in around two to three per cent of children with coeliac disease and renders the immunoglobulin A-based screen falsely negative; when deficiency is found, immunoglobulin G-based tests such as anti-deamidated gliadin peptide are used instead. [3]
3. The ESPGHAN 2020 no-biopsy pathway applies in a symptomatic child whose immunoglobulin A anti-tissue-transglutaminase titre is at or above ten times the upper limit of normal, with a positive endomysial antibody on a separate serum sample and a normal total immunoglobulin A. Human leukocyte antigen typing and a specific symptom profile are no longer required in the 2020 revision. [1] [4]
4. This is wrong because the anti-tissue-transglutaminase and endomysial antibodies fall within weeks and the mucosa heals within months on a gluten-free diet, so the serology and biopsy become uninterpretable. The diagnosis must be confirmed before the diet is started; otherwise a formal gluten challenge is needed, which is symptom-laden and unpleasant. [1]
5. The management is a strict lifelong gluten-free diet excluding wheat, barley and rye with a specialist dietitian, correction of the iron deficiency, and monitoring of symptom resolution, catch-up growth and a falling anti-tissue-transglutaminase titre that should normalise within six to twelve months, with annual review and screening of first-degree relatives. The outlook on a strict diet is excellent. [5]

SAQ 2 — The toddler with diarrhoea and failure to thrive (20 marks, ~15 minutes)

An eighteen-month-old boy presents with a four-month history of loose, pale, bulky stools four to five times a day, a progressively distended abdomen, irritability and a poor appetite. He started on gluten-containing cereals at six months. His weight has fallen from the fiftieth to below the third centile. He is pale with wasted buttocks and a distended abdomen. He eats a gluten-containing diet. [2]

Questions

1. Give the most likely diagnosis and the features that support it. (5 marks) [2]
2. Give the differential diagnosis and the single test that best separates coeliac disease from cystic fibrosis. (4 marks) [2]
3. Outline the diagnostic pathway and the role of duodenal biopsy in this age group. (5 marks) [1]
4. Describe the Marsh histology you would expect on a duodenal biopsy. (3 marks) [1]
5. Outline the management and the monitoring plan. (3 marks) [5]

Model answer (must-hit)

1. The most likely diagnosis is classic coeliac disease. The supporting features are the onset of chronic pale bulky steatorrhoeic stools after the introduction of gluten at weaning, the distended abdomen with wasted buttocks and irritability, and the marked fall across the weight centiles with a poor appetite, the classic face of the disease in a toddler. [2]
2. The differential includes cow's milk protein enteropathy, post-enteritis enteropathy with secondary lactose malabsorption, cystic fibrosis with pancreatic insufficiency, chronic giardiasis and the rare congenital enteropathies. The single test that best separates coeliac disease from cystic fibrosis is faecal elastase, which is low in pancreatic insufficiency and normal in coeliac disease, alongside the coeliac serology and a sweat test where indicated. [2]
3. The pathway begins with immunoglobulin A anti-tissue-transglutaminase plus a total immunoglobulin A on a gluten-containing diet. In a toddler the no-biopsy pathway is less often applied, so when the titre is high the diagnosis is confirmed with a positive endomysial antibody, and when the titre is moderate or the picture is not classic the standard remains duodenal biopsy with multiple biopsies including the duodenal bulb. [1]
4. The expected Marsh grade is three, showing villous atrophy with crypt hyperplasia and increased intraepithelial lymphocytes, graded as Marsh three-a for partial, three-b for subtotal and three-c for total villous atrophy. [1]
5. The management is a strict lifelong gluten-free diet with a specialist dietitian, correction of the iron and any folate or vitamin D deficiency, and monitoring of symptom resolution, catch-up growth and a falling anti-tissue-transglutaminase titre, with screening of the parents and siblings and annual review. [5]