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Mayo Test ID HGUCR Mercury/Creatinine Ratio, Random, Urine


Specimen Required


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

Supplies: Urine Tubes, 10 mL (T068)

Collection Container/Tube: Clean, plastic urine container with no metal cap or glued insert

Submission Container/Tube: Plastic, 10-mL urine tube or clean, plastic aliquot container with no metal cap or glued insert

Specimen Volume: 3 mL

Collection Instructions:

1. Collect a random urine specimen.

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


Useful For

Detecting mercury toxicity, a toxic heavy metal, using random urine specimens

Profile Information

Test ID Reporting Name Available Separately Always Performed
HGCU Mercury/Creatinine Ratio, U No Yes
CRETR Creatinine, Random, U No Yes

Method Name

HGCU: Triple-Quadrupole Inductively Coupled Plasma Mass Spectrometry (ICP-MS/MS)

CRETR: Enzymatic Colorimetric Assay

Reporting Name

Mercury/Creat Ratio, Random,U

Specimen Type

Urine

Specimen Minimum Volume

1.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 7 days
  Frozen  7 days

Reject Due To

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Clinical Information

The correlation between the levels of mercury (Hg) excretion in the urine and the clinical symptoms is considered poor.

 

Previous thought indicated urine as a more appropriate marker of inorganic mercury because organic mercury represented only a small fraction of urinary mercury. Based on possible demethylation of methylmercury within the body, urine may represent a mixture of dietary methylmercury and inorganic mercury. Seafood consumption can contribute to urinary mercury levels (up to 30%),(1) which is consistent with the suggestion that due to demethylation processes in the human body, a certain proportion of urinary mercury can originate from dietary consumption of fish/seafood.(2)

 

Small amounts of mercury are often present in urine, often stemming from environmental exposure or from dental amalgam. The amount of mercury in urine depends upon the form of mercury, the level and duration of mercury exposure, and the elapsed time between exposure and urine sample collection.

 

For potential mercury vapor exposure: urine mercury levels are unlikely to be useful for assessing potential health effects from short-term, low-level exposures to mercury vapor because such exposures are unlikely to result in mercury urine levels elevated above typical values. High level mercury vapor exposure or long-term, low-level vapor exposures may result in elevated urine mercury levels, which can indicate potential for health effects. Random urine mercury level is adjusted to concentration of creatinine.

 

Urine mercury concentrations in unexposed individuals are typically less than 10 mcg/L (50 nmol/L) or 2 mcg/g creatinine. Twenty-four-hour urine concentrations of 30 mcg/L to 100 mcg/L (150-499 nmol/L) may be associated with subclinical neuropsychiatric symptoms and tremor, while concentrations greater than 100 mcg/L (499 nmol/L) can be associated with overt neuropsychiatric disturbances and tremors.(4)

 

Mercury concentrations of greater than 10 mcg/g creatinine may associate with subtle effects on visual memory, attention, manual coordination, mood, increased levels of fatigue and confusion. Higher level of urine mercury is associated with increasing frequent and severe nervous system changes in personality, cognition, and coordination.(3)

 

Mercury concentrations of 20 mcg/g to 35 mcg/g creatinine may be associated with hand tremors and potential kidney damage.(3)

Reference Values

MERCURY/CREATININE:

0-17 years: Not established

≥18 years: <2 mcg/g creatinine

 

CREATININE:

≥18 years: 16-326 mg/dL

Reference values have not been established for patients who are younger than 18 years of age. 

Interpretation

Daily urine excretion of mercury above 50 mcg/day indicates significant exposure (per World Health Organization standard).

Cautions

To avoid contamination by dust, specimen should be collected away from the site of suspected exposure.

Clinical Reference

1. Snoj Tratniid J, Falnoga I, Mazej D, et al. Results of the first national human biomonitoring in Slovenia: Trace elements in men and lactating women, predictors of exposure and reference values Int. J. Hyg Environ Health. 2019;222(3):563-582

2. Sherman LS, Blum JD, Franzblau A, Basu N. New insights into biomarkers of human mercury exposure using naturally occurring mercury stable isotopes. Environ Sci and Tech. 2013;47(7):3403-3409

3. McKelvey W, Alex B, Chernov C, et al. Tracking Declines in Mercury Exposure in the New York City Adult Population, 2004-2014. J Urban Health. 2018;95(6):813-825

4. Agency for Toxic Substances and Disease Registry. Atsdr - addendum to the toxicological profile: Mercury. 2022.

5. Lee R, Middleton D, Caldwell K, et al. A review of events that expose children to elemental mercury in the United States. Environ Health Perspect. 2009;117(6):871-878

6. Bjorkman L, Lundekvam BF, Laegreid T, et al. Mercury in human brain, blood, muscle and toenails in relation to exposure: an autopsy study. Environ Health. 2007 11;6:30

7. Bernhoft RA. Mercury toxicity and treatment: a review of the literature. J Environ Public Health. 2012;2012:460508. doi:10.1155/2012/460508

8. Strathmann FG, Blum LM: Toxic elements. In: Rifai N, Chiu RWK, Young I, Burnham CD, Wittwer CT, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier; 2023:chap 44

Method Description

Mercury:

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

 

Creatinine:

The enzymatic method is based on the determination of sarcosine from creatinine with the aid of creatininase, creatinase, and sarcosine oxidase. The liberated hydrogen peroxide is measured via a modified Trinder reaction using a colorimetric indicator. Optimization of the buffer system and the colorimetric indicator enables the creatinine concentration to be quantified both precisely and specifically.(Package insert: Creatinine plus ver 2. Roche Diagnostics; V15.0, 03/2019)

Specimen Retention Time

14 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

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

CPT Code Information

83825

82570

LOINC Code Information

Test ID Test Order Name Order LOINC Value
HGUCR Mercury/Creat Ratio, Random,U 13465-0

 

Result ID Test Result Name Result LOINC Value
608903 Mercury/Creatinine Ratio, U 13465-0
CRETR Creatinine, Random, U 2161-8

Day(s) Performed

Monday through Friday

Report Available

2 to 4 days