Laboratory role in toxicology investigations
Suspected poisoning is a common presentation, including deliberate, accidental and occupational exposure; but with supportive treatment, complete recovery is often expected. In most cases, routine analyses are able to support diagnosis, and it is rare that specialist investigations are required.
The following routine Biochemistry analyses are available on a 24-hour basis:
- Urea and electrolytes (sodium, potassium, urea, creatinine, eGFR)
- Glucose
- Calcium, albumin, magnesium
- Liver function tests (ALT, ALP, total bilirubin, albumin)
- Chloride, bicarbonate and anion gap
- Plasma osmolality and osmolar gap
- Creatinine kinase
In addition, the laboratory offers a number of specific toxicology investigations are available on a 24-hour basis, in line with recent guidance. Please see individual test pages for guidance on requesting and interpretation.
Toxicology requests will only be processed on a case-by-case basis following discussion between the clinical team and the Duty Biochemist.
Investigations should only be requested if they are to aid diagnosis or directly influence the management of the patient.
The following information must be provided:
- History of the patient
- Signs and symptoms of poisoning
- Specify what drugs are suspected to have been taken - this will direct the analysis carried out
- Medication given since admission
- Date and time of ingestion in relation to hospital admission
- Name and bleep number of requesting consultant
- Any medico-legal issues
There are several different options for screening samples for drugs and toxins, from a Drugs of Abuse screen to a full Toxicology screen. These analyses provide a qualitative assessment for each drug (i.e. postive/negative). If specific drug concentrations are required, contact the Duty Biochemist to discuss.
Please supply full clinical details when requesting drug screening, as this ensures that the referral laboratory is able to provide the most appropriate service. If the patient has received any drugs in hospital, please also state this on the request form, as these will also be identified by the screen.
The referral laboratory also offers laxative/diuretic/volatile substance screening as clinically indicated.
The majority of specialist toxicology investigations are referred to external laboratories for analysis. This process is tightly regulated, in order to ensure an efficient service.
Investigations should only be requested if they are to aid diagnosis or directly influence the management of the patient.
The following assays are not directly available, but urgent analysis may be facilitated if clinically necessary:
- Arsenic
- Carbamazepine
- Cholinesterase
- Cyanide
- Ethylene glycol
- Lead
- Mercury
- Methanol
- Phenobarbital
- Phenytoin
- Thallium
Cases where there is a suspicion of drink spiking should be referred to the police and will not be processed by the laboratory unless the result will directly affect clinical management. The urine must be collected within 12-24 hours of the suspected incident as drugs such as Gamma-hydroxybutyrate (GHB), also known as the date rape drug, are undetectable in the urine 12-24 hours following administration/ingestion.
Our laboratory cannot provide a service for sending specimens out of hours and should any samples require urgent analysis, the wards are responsible for the sending of specimens.
For on-call management contact TOXBASE on 0844 892 0111 or the West Midlands Toxicology laboratory directly on 0121 507 4135/4 to determine best practice.
Please inform the laboratory of any discussions and specimens sent.