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22697 Mercury, Blood (HG)

Mercury, Blood (HG)
Test Code: MERC
Synonyms/Keywords
Mercury (Hg), Hg (Mercury)
Useful For
​Detecting mercury toxicity
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​Whole blood Royal Blue Top Tube (RBTT) (EDTA) Vacutainer plastic trace element blood collection tube​ Full tube ​ 0.3 mL​
Collection Processing Instructions
​Send specimen in original tube.
 
Additional Information: High concentrations of gadolinium and iodine are known to interfere with most metals tests. If either gadolinium- or iodine-containing contrast media has been administered, a specimen should not be collected for 96 hours.
Specimen Stability Information
Specimen Type Temperature Time
Whole blood​ ​ ​ Refrigerated (preferred)​ 28 days​
Ambient ​ 28 days​
Frozen ​ 28 days​
Rejection Criteria
Green top (heparin) tube​
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Mayo Clinic Laboratories
Monday through Saturday​
1-3 day
Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)​
Reference Lab
Test Information

​Mercury (Hg) is essentially nontoxic in its elemental form. If Hg(0) is chemically modified to the ionized, inorganic species, Hg(2+), it becomes toxic. Further bioconversion to an alkyl Hg, such as methyl Hg ([CH3Hg][+]), yields a species of mercury that is highly selective for lipid-rich tissue such as neurons and is very toxic. The relative order of toxicity is:

 Not Toxic - Hg(0) < Hg(2+) << [CH3Hg](+) -- Very Toxic

Mercury can be chemically converted from the elemental state to the ionized state. In industry, this is frequently done by exposing Hg(0) to strong oxidizing agents such as chlorine.

Hg(0) can be bioconverted to both Hg(+2) and alkyl Hg by microorganisms that exist both in the normal human gut and in the bottom sediment of lakes, rivers, and oceans. When Hg(0) enters bottom sediment, it is absorbed by bacteria, fungi, and small microorganisms; they metabolically convert it to Hg(2+), [CH3Hg](+), and (CH3)(2+)Hg. Should these microorganisms be consumed by larger marine animals and fish, the mercury passes up the food chain in rather toxic form.

Mercury expresses its toxicity in 3 ways:

-Hg(2+) is readily absorbed and reacts with sulfhydryl groups of protein, causing a change in the tertiary structure of the protein-a stereoisomeric change-with subsequent loss of the unique activity associated with that protein. Because Hg(2+) becomes concentrated in the kidney during the regular clearance processes, this target organ experiences the greatest toxicity.

-With the tertiary change noted previously, some proteins become immunogenic, eliciting a proliferation of T lymphocytes that generate immunoglobulins to bind the new antigen; collagen tissues are particularly sensitive to this.

-Alkyl Hg species, such as [CH3Hg](+), are lipophilic and avidly bind to lipid-rich tissues such as neurons. Myelin is particularly susceptible to disruption by this mechanism.

 Members of the public will occasionally become concerned about exposure to mercury from dental amalgams. Restorative dentistry has used a mercury-silver amalgam for approximately 90 years as a filling material. A small amount of mercury (2-20 mcg/day) is released from a dental amalgam when it was mechanically manipulated, such as by chewing. The habit of gum chewing can cause release of mercury from dental amalgams greatly above normal. The normal bacterial flora present in the mouth converts a fraction of this to Hg(2+) and [CH3Hg](+), which was shown to be incorporated into body tissues. The World Health Organization safety standard for daily exposure to mercury is 45 mcg/day. Thus, if one had no other source of exposure, the amount of mercury released from dental amalgams is not significant. Many foods contain mercury. For example, commercial fish considered safe for consumption contain less than 0.3 mcg/g of mercury, but some game fish contain more than 2.0 mcg/g and, if consumed on a regular basis, contribute to significant body burdens.

Therapy is usually monitored by following urine output; therapy may be terminated after urine excretion is below 50 mcg/day.

 

Reference Range Information
Normal:  <10 ng/mL
Reference values apply to all ages. 
Interpretation
​The quantity of mercury (Hg) found in blood and urine correlates with degree of toxicity. Hair analysis can be used to document the time of peak exposure if the event was in the past.
 
Normal whole blood mercury is usually <10 ng/mL.
 
Individuals who have mild exposure during work, such as dentists, may routinely have whole blood mercury levels up to 15 ng/mL.
 
Significant exposure is indicated when the whole blood mercury is >50 ng/mL if exposure is due to alkyl Hg, or >200 ng/mL if exposure is due to Hg(+2).
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​83825
Synonyms/Keywords
Mercury (Hg), Hg (Mercury)
Ordering Applications
Ordering Application Description
​Centricity ​Mercury-Blood
​Cerner ​Mercury Level (8618)
​COM ​Mercury, Blood
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​Whole blood Royal Blue Top Tube (RBTT) (EDTA) Vacutainer plastic trace element blood collection tube​ Full tube ​ 0.3 mL​
Collection Processing
​Send specimen in original tube.
 
Additional Information: High concentrations of gadolinium and iodine are known to interfere with most metals tests. If either gadolinium- or iodine-containing contrast media has been administered, a specimen should not be collected for 96 hours.
Specimen Stability Information
Specimen Type Temperature Time
Whole blood​ ​ ​ Refrigerated (preferred)​ 28 days​
Ambient ​ 28 days​
Frozen ​ 28 days​
Rejection Criteria
Green top (heparin) tube​
Useful For
​Detecting mercury toxicity
Reference Range Information
Normal:  <10 ng/mL
Reference values apply to all ages. 
Interpretation
​The quantity of mercury (Hg) found in blood and urine correlates with degree of toxicity. Hair analysis can be used to document the time of peak exposure if the event was in the past.
 
Normal whole blood mercury is usually <10 ng/mL.
 
Individuals who have mild exposure during work, such as dentists, may routinely have whole blood mercury levels up to 15 ng/mL.
 
Significant exposure is indicated when the whole blood mercury is >50 ng/mL if exposure is due to alkyl Hg, or >200 ng/mL if exposure is due to Hg(+2).
For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Mayo Clinic Laboratories
Monday through Saturday​
1-3 day
Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)​
Reference Lab
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​83825
For most current information refer to the Marshfield Laboratory online reference manual.