Operational Pathway for Paediatric Urine Toxicology

• Target Group
• Poisoning - when to consider it
• Accidental poisoning
• Intentional poisoning
• Practicalities and Considerations when performing a Urine Toxicology Test
• Contact Information

This Pathway covers the following

• When to consider poisoning
• How to request, collect and send a urine sample for toxicology
• What is tested as standard?
• What additional tests can be requested after discussion with the lab?
• Turnaround times for results
• Important contact information
• Common drugs/medications/substances that can cause positive results

Target Group

This Guideline applies to Paediatric patients (up to 16th birthday). It is aimed at Doctors and Nurses on Paediatric wards and units and in the Emergency Department. The aim of this guideline is to improve patient care where poisoning has been considered, through a process where a quick toxicology result is achieved.

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Poisoning - when to consider it

Poison is defined as a substance causing illness or death when eaten, drunk or absorbed into the body by other means.

Toxbase provides valuable advice on how to manage specific substance ingestion. Your General Paediatric or Accident and Emergency Department should have a login that can be used.

Poisoning may be:

• Accidental
• Neglectful or due to single acts of omission
• Deliberate - clearly a form of child abuse.

Gray & Bentovim (1996) described 11 cases with children ranging from 4 weeks to 12 years and 3 months where a carer had ‘actively administered substances which were harmful to the child or where a parent had been actively interfering with the child's medical treatment’.

Repeated poisoning may be due to negligence but the consequences for the child may be equally as catastrophic as poisoning by intent or in order to fabricate illness and should be assessed as possible abuse.

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Accidental poisoning

Accidental poisoning is seldom fatal. The peak age is 2–3 years, there is often a lapse in adult supervision and ingestions usually take place at home. In the aforementioned study in 60% of cases the substance ingested was not in its usual storage place and 60% of substances were not in child-resistant containers; 22% of children were admitted to hospital, < 10% needed intensive care and there were no fatalities.

Accidents may occur even in well-regulated homes but repeated ingestion should be looked at as neglectful, and deliberate poisoning considered. It is also appropriate to look at parental behavior and the family situation. Look for depression or mental health problems; substance or alcohol misuse; other signs of abuse or neglect.

Common examples of accidental drug ingestions include analgesics, anxiolytics, the contraceptive pill, cough medicine and iron. Bleach, detergents and petroleum products account for most of the household substances ingested.

Parents may misread instructions on a bottle and overdose a child but then the history is clear, whereas if parents deliberately overdose their child they will conceal the history.

If symptoms are severe – for example seizures, coma, intractable vomiting – consider whether an unusual substance such as salt, insulin or anti-consultants has been administered. Laxatives, which are easily available, are also often used deliberately.

The age of the child is also important. Toddlers aged 18 months to 3 years explore, test and taste whatever they find; by 4–5 years most children will know not to eat pills. When a young infant (not yet at the crawling stage) is brought, the facts of the story need to be very carefully obtained and a vigilant stance adopted.

Children from 3 years are able to give a history and tell you if they ‘ate grandpa's sweeties’ or if mummy gave them herself. Children as young as 6 years do deliberately overdose, but this is rare under 10 years. If any child or adolescent overdoses the reasons why must be explored.

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Intentional poisoning

#mce_temp_url#Intentional poisoning of children, whilst rare, is a significant form of child abuse. It may present with other overt signs of physical or sexual abuse but often may present as a child with a diagnostic dilemma. The more bizarre the clinical situation the greater the likelihood for intentional poisoning.

Drugs/substances may be used to deliberately cause harm to a child or to fabricate or induce illness. They may also be used in the following situations:

• To keep a child quiet, for example the use of sedatives at night, or to make the child compliant, with high doses of anxiolytics.
• Drugs may be used to allow sexual abuse to occur.
• Adults who abuse drugs may involve even very young children in their habit
• There are many examples of children of all ages dangerously intoxicated with alcohol. This may be deliberate poisoning, or unsupervised drinking.

Intentional Salt Poisoning

Deliberate salt poisoning is a serious cause of hypernatraemia in children and represents a medical emergency. Salt poisoning is rare, but should be considered, if there is hypernatraemia without clinical evidence of severe dehydration. Patients at highest risk are those without access to free water. A history of previous unexplained episodes of hypernatraemia should raise suspicion. A history of vomiting and diarrhoea does not exclude the diagnosis.

Once suspected, securing all administered substances is critical to prove the diagnosis. A high sodium concentration in a gastric aspirate can further help to prove the diagnosis of salt poisoning.

A urine U+E test (random urine sample in a plain white-top universal) should be requested urgently in children with hypernatraemia without dehydration; a high urine sodium is indicative of possible excess salt ingestion. 

Calculating the free water deficit (the minimal expected weight loss in hypernatraemic dehydration) and comparing it with the observed weight loss is helpful to assess the possibility of salt poisoning. If no recent weight is available, the weight after normalisation of plasma sodium should be used for comparison. Fractional excretion of sodium (FENa) is a key investigation, but if not available, clinical parameters, such as signs of dehydration and weight might be the only indicators. Moreover, FENa is difficult to interpret in patients with abnormal or unstable glomerular filtration rate.

See Table 1 for features of poisoning, whether due to accident, neglect or willful intent by care giver. 

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Practicalities and Considerations when performing a Urine Toxicology Test

Consent

Verbal consent should be requested and documented in the notes.  Where factitious or induced illness is being considered, or consent has been refused, obtaining consent should be discussed with the named doctor, social services/police and the trust safeguarding and legal teams.

Urine collection and storage

Sample:

Plain white topped universal container.  Use a urine bag, cotton wool pad or direct collection as appropriate for the child.

Minimum volume:

0.5mL is sufficient for the routine drugs of abuse screen. 

10 -20 mL urine recommended if ethanol or further tests are required.

Storage:

Refrigerate if possible if not sending to the lab immediately.

ICE requesting:

• Request urine drugs of Abuse Screen (Random). 
• Request urine alcohol if required.
• Enter all relevant information into the clinical details field including prescribed medications and substances you wish to be tested. 
  • This may not be displayed in full on the request form but can be viewed in ICE by the laboratory staff and other relevant permitted users. 
  • Please do not annotate the request form after printing with clinical details or further test requests.  There is a risk that the form may be misplaced therefore this information may be lost. 
  • If additional information/requesting is required please print a new request.

Available tests

All samples will be tested for the standard drugs of abuse panel, which includes:

• Morphine, 6-monoacetylmorphine, codeine, dihydrocodeine,
• Amphetamine
• Benzoylecgonine (cocaine metabolite)
• Nordiazepam and oxazepam (Diazepam metabolites)
• Cannabis
• Methadone and EDDP (metabolite)
• Buprenorphine and norbuprenorphine (metabolite)

Further tests are available if needed and should be discussed with the laboratory.  There is usually no time limit for add-on requests – please contact the lab to discuss.

Additional tests (please contact lab to discuss):

In-house testing:

• Ethanol, Ketamine, MDMA, Oxycodone, Pholcodine, Diazepam, Temazepam, Nitrazepam, Gabapentin, Pregabalin, Tramadol.

Send-away testing:

• Synthetic cannabinoid screen (selected common synthetic cannabinoids). 
• Extended unknown drug screen (1300 drugs and metabolites by LC-QTOF analysis).

The test repertoire is continually updated according to current trends in drug use. 

Send-away / Referred test requests for Toxicology MUST be discussed with the lab before a sample can be sent.

Contact the Toxicology Lab (x66063 / 64852) and ask to speak to the Clinical Scientist

Informing the laboratory and transporting samples

Urgent analysis must be arranged with the toxicology section (Contact details below)

Urgent processing cannot be guaranteed if the laboratory is not informed.

Send urgent samples by taxi to Specialist Laboratory Medicine, Block 46, St James’s Hospital to arrive 9:00-16:30 Monday-Friday.  Mark the request form clearly: “Urgent urine toxicology – send directly to Block 46”. 

Non-urgent samples can be sent to the main laboratory. 

Turnaround time and results

Toxicology samples are processed routinely twice a week.  There is no out of hours or weekend service.  We aim to process urgent samples within 1 working day of receipt with results ready within 2-3 working days (e.g. results from samples received on Friday should be ready by the following Tuesday/Wednesday).

All positive results will be telephoned back to the requesting consultant.  Please give contact name and number in the clinical details field if you wish a different individual to receive the results. 

All results are reported to PPM+.

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Contact Information

Laboratory contact details

Key contacts:

Consultant Clinical Scientist: Dr Carys Lippiatt Ext 64852 or via switchboard [carys.lippiatt@nhs.net].

Principal Clinical Scientist: Dr Elizabeth Fox Ext 64860 [elizabeth.fox4@nhs.net].

Advanced Biomedical Scientist: Mr James Booth Ext 64204 [jamesbooth@nhs.net].

Toxicology Lab: Ext 66063

Specimen Reception: Ext 64195

Duty Biochemist: Ext 26922 Option 2 / Bleep 2607 [leedsth-tr.Biochemist@nhs.net].

General Paediatrics Registrar bleep 2111

Specialities Registrar bleep 1904

PICU Registrar via ward 27447

Paeds ED 25549

Address for urgent samples:

Specialist Laboratory Medicine,

Block 46,

St James Hospital,

Beckett Street,

LS9 7TF

Further information on Urine Toxicology Results

Common drugs/medications/substances that can cause positive results:

Other sources of positive results (not exhaustive list). This list does not apply to point-of care tests which may be subject to more interferences:

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