Audit of reducing sugars requesting

1. Audit of reducing sugars requesting Chris Stockdale

2. Reducing sugars • A sugar which has an aldehyde group capable of reducing Cu(II)

3. % reducing sugar 0 0.25 0.5 0.75 1 2 Sugar TLC Xylose Glucose Fructose Galactose Sucrose Maltose Lactose

4. Analysis of reducing sugars requesting • Requests from 30/3/11 to 4/5/11 • 66 faeces requests, 13 urine requests • Sugar TLC performed on 56 of these (47 faeces, 9 urines)

5. Urinary reducing sugars STM BRHC Other hospitals

6. When do reducing substances appear in urine?

8. Reasons for urine requests Hyperbilirubinaemia/jaundice Hypoglycaemia Renal tubular acidosis • Reducing substances testing recommended by Metbionet and/or local guidelines for investigation of: • hypoglycaemia • conjugated hyperbilirubinaemia • early presenting jaundice • prolonged jaundice

9. Reducing sugars testing in galactosaemia and HFI • False positive results • Other causes of liver dysfunction ‘although determination of reducing substances in the urine can be used as a first simple screening test for classical galactosaemia, this test should not be used either to confirm or to reject a diagnosis’ • False negative results • Galactosaemia recent blood transfusion not on regular milk feed • HFI literature reports of false negative results

10. Action points: urine • Test no longer available • Clinicians directed to GALT testing when galactosaemia suspected • References to test withdrawn from local guideline documents

11. Faecal reducing substances

12. Faecal reducing substances STM Derriford BRHC Other hospitals Taunton GP Weston Cheltenham Bath

13. Faecal reducing substances • Why? • If sugar malabsorption is suspected • Inability to absorb a sugar will lead to its appearance in faeces

14. Lactose malabsorption • Clinically the most important form of sugar malabsorption • Lactase deficiency • Lactose accumulation in small intestine • Leads to bloating, pain, flatulence, diarrhoea, FTT, colic • Primary, secondary and developmental forms

15. Lactose malabsorption • Clinically the most important form of sugar malabsorption • Lactase deficiency • Lactose accumulation in small intestine • Leads to bloating, pain, flatulence, diarrhoea, FTT, colic • Primary, secondary and developmental forms

16. Reducing substances testing in diagnosis of lactose intolerance • False negative results • Bacterial metabolism of faecal sugars (can be reduced by freezing samples) ‘fecal reducing sugars can also be measured and become positive by excretion of a reducing sugar in the stools’ • No significant difference could be established between normal children and children with malabsorption syndromes in terms of faecal pH and sugar chromatography. Schaub & Lentze (1973) Sugars, lactic acid and pH in feces of children. A useful diagnostical approach for gastrointestinal disorders? Eur J Pediatrics, 115, 141-53.

17. Alternative tests for diagnosis of lactose intolerance • Hydrogen breath test • Trial of lactose free diet

18. Action points: faeces • Test only available in children up to 16 • Requestors alerted to possibility of false negative results • Advise freezing of samples from external locations • Test no longer performed on fully formed stools • Sugar TLC performed only on samples with 0.5% or above reducing substances

19. Results of the changes to the availability of these tests • Reducing substances testing decreased from 79 to 43 • Sugar TLC testing decreased from 56 to 12

20. Acknowledgements • Clinical Biochemistry, BRI • Ann Bowron • Dr Vicki Powers • Dr Janet Stone • Bristol Royal Hospital for Children • Dr Christine Spray • Metabolic Biochemistry Network • http://www.metbio.net/