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Test ID TLB Thallium, Blood

Reporting Name

Thallium, B

Useful For

Detecting toxic exposure in whole blood specimens

Specimen Type

Whole blood

Specimen Required

Patient Preparation: High concentrations of gadolinium and iodine are known to interfere with most metal tests. If either gadolinium- or iodine-containing contrast media has been administered, a specimen should not be collected for 96 hours.

Supplies: Metal Free B-D Tube (EDTA), 6 mL (T183)

Container/Tube: Royal blue top (EDTA) plastic trace element blood collection tube

Specimen Volume: Full tube

Collection Instructions:

1. See Metals Analysis Specimen Collection and Transport for complete instructions.

2. Send specimen in original tube. Do not aliquot.

Specimen Minimum Volume

0.3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole blood Refrigerated (preferred) 28 days
  Ambient  28 days
  Frozen  28 days

Reference Values

0-17 years: Not established

≥18 years: <2 ng/mL

Day(s) Performed

Tuesday, Friday

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
TLB Thallium, B 5743-0


Result ID Test Result Name Result LOINC Value
8149 Thallium, B 5743-0

Clinical Information

Thallium is odorless, tasteless and found in trace amounts in the earth's crust. It is used in the manufacturing of electronic devices, switches, and closures. It had previously been used in rodenticides. The greatest exposure can occur from eating food (eg, fruits and vegetables) since it's easily taken up by plants through the roots. Cigarette smoking is also a source of exposure. Accidental ingestion may lead to vomiting, diarrhea, and leg pains, followed by a severe and sometimes fatal sensorimotor polyneuropathy. Peripheral neuropathy may occur within 1 week of exposure, while hair loss begins and continues for several weeks. Gastrointestinal symptoms, including pain, diarrhea, and constipation have also been reported in acute ingestion, along with myalgias, pleuritic chest pain, insomnia, optic neuritis, hypertension, cardiac abnormalities, Mees lines, and liver injury. Most thallium is excreted in the urine, can be found within an hour after exposure, and can be detected as long as two months after exposure.


Normal thallium blood concentrations are less than 1 ng/mL.


Significant exposure is associated with thallium concentrations in blood greater than 10 ng/mL and as high as 50 ng/mL. The long-term sequelae from such an exposure is poor.


Patients exposed to high doses of thallium (>1 g) present clinically with alopecia (hair loss), peripheral neuropathy, seizures, and kidney failure


No significant cautionary statements

Clinical Reference

1. Pelcloval D, Urbanl, P, Ridsonl P, et al. Two-year follow-up of two patients after severe thallium intoxication. Hum Exper Toxicol. 2009;28:263-272

2. Zhao G, Ding M, Zhang B, et al. Clinical manifestations and management of acute thallium poisoning. Eur Neurol. 2008;60:292-297

3. Agency for Toxic Substances and Disease Registry: Toxicological profile for thallium. US Department of Health and Human Services; July 1992. Available at

4. Strathmann FG, Blum LM. Toxic elements. In: Rifai N, Chiu RWK, Young I, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier; 2023:455.e55

Method Description

The metal of interest is analyzed by inductively coupled plasma mass spectrometry.(Unpublished Mayo method)

Report Available

2 to 5 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Method Name

Inductively Coupled Plasma Mass Spectrometry (ICP-MS)