Audit of reducing sugars requesting

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Audit of reducing sugars requesting
Chris Stockdale
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Reducing sugars

• A sugar which has an aldehyde group capable of
  reducing Cu(II)

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reducing sugar
0
0.25
0.5
0.75
1
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Sugar TLC
Xylose Glucose Fructose Galactose Sucrose Maltos
e Lactose
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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)

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Urinary reducing sugars
STM
BRHC
Other hospitals
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When do reducing substances appear in urine?
Cause Reducing substances in urine
Diabetes mellitus Glucose
Galactosaemia Galactose (glucose)
Hereditary fructose intolerance Fructose
Essential fructosuria (benign) Fructose
Essential pentosuria (benign) L-xylulose
Alkaptonuria Homogentisic acid
Fanconi syndrome Glucose, galactose
Liver dysfunction Galactose, fructose
Citrin deficiency Galactose
Hereditary tyrosinaemia p-Hydroxyphenylpyruvic acid
Drugs Salicylate, levodopa, cephalosporins
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Galactosaemia Hereditary fructose intolerance
Enzyme affected Galactose 1 phosphate uridyl transferase (GALT) Aldolase B
Incidence 1/45k 1/20k
Symptoms Liver kidney dysfunction, brain damage, hypoglycaemia Liver renal tubular dysfunction, hypoglycaemia, avoidance of fructose containing foods
Onset Symptoms in first week of life Symptoms upon weaning
Diagnosis GALT activity assay RBC galactose-1-phosphate Urine galactose/galactitol DNA analysis Nutritional history DNA analysis
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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

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Reducing sugars testing in galactosaemia and HFI
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 positive results
• Other causes of liver dysfunction

• False negative results
• Galactosaemia recent blood transfusion not
  on regular milk feed
• HFI literature reports of false negative results

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Action points urine

• Test no longer available
• Clinicians directed to GALT testing when
  galactosaemia suspected
• References to test withdrawn from local guideline
  documents

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Faecal reducing substances
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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

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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

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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

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Reducing substances testing in diagnosis of
lactose intolerance
fecal reducing sugars can also be measured and
become positive by excretion of a reducing sugar
in the stools

• False negative results
• Bacterial metabolism of faecal sugars (can be
  reduced by freezing samples)

• 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.

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Alternative tests for diagnosis of lactose
intolerance

• Hydrogen breath test
• Trial of lactose free diet

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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

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Results of the changes to the availability of
these tests

• Reducing substances testing decreased from 79 to
  43

Reason Number of samples excluded
Urine 13
Faecal requests on patients gt16 4
Fully formed samples 20
Total 37

• Sugar TLC testing decreased from 56 to 12

Reason Number of samples excluded
Urine 9
Faecal requests on patients gt16 4
Fully formed samples 11
0.25 reducing substances 20
Total 44
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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/