Appendix 14 – Constipation, Coeliac screening (including HLA typing) and gastroenterological complications
Background –
There are a number of conditions that are more common in Down Syndrome. These include gastro-oesophageal reflux disease (GORD), Hirschsprung’s disease, pyloric stenosis, duodenal atresia, aspiration, coeliac disease, constipation and food allergies. This presentation gives an excellent overview and covers everyone is considerable detail. https://www.dsmig.org.uk/wp-content/uploads/2017/12/RCPCH-SIG-Gastrointestinal-manifestations-of-Down-syndrome.pdf
In particular, these 3 conditions need to be highlighted as the most common and also ones that need to be assessed and managed at every patient review by clinicians:
GORD – signs, symptoms, red flags, investigations, management, when to refer.
Coeliac disease – symptoms, signs, investigations and management, when to refer.
Constipation – recognition, management and behavioural interventions. As this is often a major issue for many, the slides have been copied out below:
Constipation:
Stooling issues and DS
Constipation Prevalence 20-36% – Increased with hypotonia, communication and behaviour issues, supplementary feeds. Constipation can happen early on due to low muscle tone, poor mobility, diet and inadequate fluid intake etc or even short segment Hirschprungs. Need to exclude organic disease. Need to check for and manage possible overflow +/- stool withholding which are common issues.
Diarrhoea: often due to overflow. But could be due to stimulant laxatives. If infective is associated with initial pyrexia. Consider gut dysbiosis associated with lactose intolerance/malabsorption.
Triggers for constipation:
Varies between children
Elucidate in the history: age of onset.
Parental expectations: address them in the treatment strategy.
Also consider: pain (e.g. a fissure) • Fever/dehydration • Dietary intake (in terms of fibre content) • Psychological issues and expression of distress • Toilet training/aversion • Other medicines, other conditions • Family history of constipation.
NICE recommended treatment
Investigate children with red flags
For faecal impaction – NICE: Polyethylene glycol 3350 + electrolytes (e.g. Movicol Paediatric Plain) • Escalating dose regimen (= first-line treatment). • Adjust the dose of Movicol according to response. • Risk of increased overflow (consider impact on school). • Review soon • Reduce the dose of Movicol when disimpaction is achieved – Maintenance dose might be half disimpaction dose. • BUT....
Add stimulant (senna/picosulphate) if Movicol alone does not work (but can cause overflow++).
Substitute a stimulant laxative if Movicol is not tolerated. • Add another laxative such as lactulose (toddlers) or bisacodyl (older children) if stools are hard.
Medication may be needed for weeks/months. • Children who are toilet training should remain on laxatives until toilet training is well established. • Gradually reduce the dose over a period of months in response to stool consistency and frequency; and increase if symptoms relapse. • 20-30% children with DS may require laxatives for several years.
Also laxatives are only half the story • Increase fibre content (to normal). • Ensure adequate hydration • Increase exercise levels (all evidence based).
Positive behavioural interventions/rewards suited to the child’s level. • Explain that treatment may take years. • Addressing the underlying trigger – Understanding of parents – Fear of toilets in younger children – Access to school toilets in school age children. • Early reassessment and reinforcement of initial messages is also key.
Other resources: Social stories/school nurse/health visitor/continence nurse and www.eric.org.uk and Free helpline: 0808 169 9949
Toileting guidance:
https://www.bbuk.org.uk/wp-content/uploads/2019/08/Top-tips-for-potty-training.pdf
Coeliac disease - Testing for Coeliac disease:
Currently the consensus in the UK is to have a low threshold for testing for coeliac disease in any child with Down Syndrome. This means a blood test for Coeliac antibodies (TTG) AND a total immunoglobulin A (IgA) at the same time. IgA can sometimes be deficient in the general population and this is what is tested when the lab looks for the coeliac test (TTG) so this can lead to a false negative result if you don’t know the IgA levels. If levels of IgA are low, then the tests need to be repeated looking for Gliadin antibodies using IgG. This can be discussed with your local lab and immunology team.
The one piece of information that is vital to this testing is “how much gluten is the child on?” The test will not be accurate if the child is not on enough gluten leading up to and during the test. He/she MUST be on gluten and it must not be removed, otherwise this invalidates the test, and not only that but the child needs to be on a sufficient amount regularly to validate the test. Many times the coeliac might be negative but it can develop later on in life so it needs to be remembered and tested for throughout childhood and adulthood.
In view of this, and that clinicians end up testing at random times, with different “thresholds'' for testing, with undue worry for parents about when and if their child will get coeliac – there is another school of thought about testing. It is feasible to do an HLA typing test (one blood test) anytime, which is not dependent on gluten intake nor age nor the IgA status and get a result that either puts the child into a group where they “are at higher risk of getting coeliac at some stage but may not” or a group which means “they will not develop coeliac.” Thereby, this means those in the 2nd group do not need random testing and parents can be reassured their child won’t develop coeliac. The first group needs testing with a low threshold for symptoms but MUST NOT come off gluten at this stage. They still may never develop coeliac and so it is about informing this group they have a higher but not complete risk of getting coeliac in their lifetime.
STATEMENT: Doctors would not put anyone on a gluten free diet until a secure diagnosis is made.
HLA testing and pathway:
The HLA test is about the potential to develop coeliac disease (CD) when positive and does not indicate that someone actually has CD. So in fact it's more useful sometimes if it's a negative, as it makes it extremely unlikely to develop coeliac disease. The other two blood tests (TTG and Anti endomysial antibody) are the ones that tell you about if someone has it or not.
To be clear, the HLA test is independent of the amount of gluten in the diet but the TTG/EMA accuracy is dependent on adequate gluten intake at the time of testing and on a normal total IgA.
We plan to test for HLA typing at 6 months with the first TFTs (recommended as per thyroid guidance 2020, DSMIG). If the result shows HLA DQ2 or DQ8 – then this means the child has the potential to develop coeliac disease, but it is not definite at all.
If the HLA markers are -ve, this child will NOT develop coeliac disease in their lifetime.
In theory you could avoid repeatedly testing them with TTG tests every few years etc. because you know that their HLA test is negative.
If their HLA tests are +VE and the TTG are negative (and they’ve been consuming adequate amounts of gluten in the run up to the test) then the person again doesn’t have coeliac disease at that time but would need repeat screening / TTG testing in 2-3 years if they remain asymptomatic and continue to be screened.
If HLA tests +VE and TTG positive then refer to paediatric gastroenterology please or your nearest paediatric gastroenterologist.
The form is here:
Do remember:
If they have not been on sufficient gluten, the TTG/EMA test may be falsely reassuring or if the baby is IgA deficient the TTG/EMA test may also be falsely reassuring, so worth a discussion with the paediatric gastroenterologist if this is a concern.
The HLA test is a one-off screening test, for like, and is irrespective of gluten intake.
Serology testing (no HLA available):
Screening for coeliac disease with TTG when symptomatic or on routine screening or if have a very low threshold for testing: If HLA has not been done, but the TTG test is positive (IgA normal), this needs repeating with EMA (endomysial antibodies) within a few weeks and a referral made to paediatric gastroenterology.
Once referral made, the waiting time is usually about 4 weeks and the paediatric dieticians will contact the family.
The child must NOT stop gluten until directed by the gastroenterologist/dietician team.
Discussion with Dr Daniel Crespi, paediatric gastroenterologist Royal Free hospital (2020):
Key recommendations for diagnosing coeliac disease (CD):
If CD is suspected, measurement of total serum IgA and IgA-antibodies against transglutaminase 2 (TGA-IgA) is superior to other combinations
We recommend against deamidated gliadin peptide antibodies (DGP-IgG/IgA) for initial testing
Only if total IgA is low/undetectable, an IgG-based test is indicated
If TGA-IgA is ≥10 times the upper limit of normal (10× ULN) and the family agrees, the no-biopsy diagnosis may be applied, provided endomysial antibodies (EMA-IgA) will test positive in a second blood sample. HLA DQ2-/DQ8 determination and symptoms are not obligatory criteria
In children with positive TGA-IgA <10× ULN at least 4 biopsies from the distal duodenum and at least 1 from the bulb should be taken