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Test Category: Specialist Biochemistry

Investigation Name:Toxic Metal Screen – Blood

Alias or Abbreviation:Heavy metal screen

Accreditation:UKAS ISO15189:2022 Accredited test: on scope

Intro:

The clinical toxic metal screen consists of a semi-quantitative ICP-MS screen of 52 elements, including heavy metals Pb, Cd, As, Hg, Cr, Co and Tl as well as some rarer elements, in blood and urine. The aim of the screen is to identify toxicologically significant elevations in metal concentrations that warrant further investigation.
Toxic metal screen results can be complex to interpret and the following are taken into account:
- Likely sources of contamination
- Clinical presentation
- Non-exposed population reference ranges
- Thresholds associated with clinically significant poisoning
- Occupational exposure limits
- ICP-MS interferences

Results are interpreted in the context of the clinical picture and only clinically relevant results are reported as a clear interpretative comment to avoid the potential for misdiagnosis and unnecessary further testing.
Where potential toxicologically significant elevations in metal concentrations are identified, these results will be confirmed by quantitative analysis wherever possible, and the results are reported.

The toxic metal is a useful tool in a number of specific situations. For example, in patients with unexplained clinical signs/symptoms suggestive of metal poisoning, in occupational exposure to a number of elements or in patients known to have been taking “herbal remedies”.
This screen is not advised in the general “worried well” due to the complexity of interpretation where there is no real clinical suspicion of exposure. Prior chelation of patients to “release” heavy metals from organs and bone is absolutely not recommended.

Pathology Laboratory:Trace Elements Laboratory

Requestable Seperately?Yes

Minimum Sample Volume:Blood: 500 µL whole blood,
Urine: 2 mL urine

Expected Turnaround Time:7 working days.
Urgent analysis where clinically indicated may be arranged directly with the laboratory.

Test Code:Blood: TMSB,
urine: TMSU

Sample Type:

Blood
Preferred: Trace element free EDTA or sodium heparin whole blood
Accepted: EDTA whole blood

Urine
Random urine collected into a plain white-top universal container.

Complex Reference Range:None, findings summarised as an interpretative comment

Collection Conditions / Other Information:Please send both blood and urine samples for the clinical toxic metal screen.
Please note the following to avoid sample contamination/misleading results:
- For arsenic, avoid any fish/seafood in diet for 5 days prior to collecting samples
- Avoid collecting urine samples via catheter bags or paper mache containers
- Trace element free EDTA or sodium heparin whole blood is preferred. Where routine EDTA tubes are used, there may be issues with contamination, particularly for manganese.
- Discard the first few milliters of blood if using a stainless steel needle, particularly for manganese
- If aluminium toxicity is suspected, please send an additional trace element free lithium heparin whole blood sample for separate plasma aluminium analysis.

To aid interpretation of results, please include the following information on the request form:
- Reason for request, suspected or known exposure, clinical signs/symptoms
- Any potential sources of contamination or causes of misleading results that were not possible to avoid as described above
N.B. We are able to perform a toxic metal screen on tablets or powders, where this is clinically relevant. Please contact the laboratory to discuss if you require this.

Referred to Another Laboratory?No

Storage Requirements:Store at 4°C prior to dispatch

Posting Address / Requirements:Ambient temperature, 1st class post.
Sandwell Health Campus,
Specialist Chemistry,
Pathology Department,
Lyndon, B71 4HJ.

EQA Scheme:No specific scheme available.
EQA material from schemes that we participate in for quantitative analysis is run when performing the assay for quality assurance.

Further information:We are a designated Supra-Regional Assay Service (SAS) Laboratory for Trace Elements.

Lead Contact Details:Dr Nicola Barlow, Consultant Clinical Scientist,
SAS Director Trace Elements Laboratory
Email: nicola.barlow1@nhs.net

Email Address For Chasing Results:rwh-tr.bcpsspecialistchemistryenquiries@nhs.net

Methodology:Inductively coupled plasma mass spectrometry

Site Sample Tested:Sandwell Health Campus

Cost:Please email: bcpspathology.info@nhs.net for further details

Contact Number:Tel: 0121 507 5162