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Test Code 0277608 Heavy Metal/Creatinine Ratio, with Reflex, Urine

Additional Codes


Mayo Test ID


Specimen Required

Patient Preparation:

-Patient should not eat seafood for a 48-hour period prior to start of collection.

-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.

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 (T068) or clean, plastic aliquot container with no metal cap or glued insert

Specimen Volume: 6 mL

Collection Instructions:

1. Collect a random urine specimen.

2. See Trace Metals Analysis Specimen Collection and Transport in Special Instructions for complete instructions.

Useful For

Preferred screening test for detection of arsenic, cadmium, mercury, and lead in random urine specimens

Profile Information

Test ID Reporting Name Available Separately Always Performed
ARSC Arsenic/Creatinine Ratio, U Yes, (order ARSCR) Yes
CDRC Cadmium/Creatinine Ratio, U Yes, (order CDRCR) Yes
HGRC Mercury/Creatinine Ratio, U Yes, (order HGRCR) Yes
PBRC Lead/Creatinine Ratio, U Yes, (order PBRCR) Yes
CDCR Creatinine Conc No Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
ASFRU Arsenic Fractionation, Random, U Yes No

Testing Algorithm

If arsenic concentration is greater than or equal to 35 mcg/L, then fractionation will be performed at an additional charge.


See Porphyria (Acute) Testing Algorithm in Special Instructions.

Method Name

ARSC, CDRC, HGRC, and PBRC: Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)

CDCR: Enzymatic Colorimetric Assay

Reporting Name

Heavy Metal/Creat Ratio, w/Reflex,U

Specimen Type


Specimen Minimum Volume

3 mL

Specimen Stability Information

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

Reject Due To









Reference Values


0-17 years: not established

≥18 years: <24 mcg/g creatinine



0-17 years: not established

≥18 years: <0.6 mcg/g creatinine



0-17 years: not established

≥18 years: <2 mcg/g creatinine



0-17 years: not established

≥18 years: <2 mcg/g creatinine



Normally, humans consume 5 to 25 mcg of arsenic each day as part of their normal diet; therefore, normal urine arsenic output is less than 35 mcg arsenic per gram creatinine (<35 mcg/g). When exposed to inorganic arsenic, the urine output may be above 1,000 mcg/g and remain elevated for weeks. After a seafood meal (seafood contains a nontoxic, organic form of arsenic), on the other hand, the urine output of arsenic may be above 200 mcg/g, after which it will decline to below 35 mcg/g over a period of 1 to 2 days.

Exposure to inorganic arsenic, the toxic form of arsenic, causes prolonged excretion of arsenic in the urine for many days. Urine excretion rates above 1,000 mcg/g indicate significant exposure. The highest value observed at Mayo Clinic was 450,000 mcg/L in a patient with severe symptoms of gastrointestinal distress, shallow breathing with classic "garlic breath," intermittent seizure activity, cardiac arrhythmias, and later onset of peripheral neuropathy.



Cadmium excretion above 3.0 mcg/g creatinine indicates significant exposure to cadmium.


Results above 15 mcg/g creatinine are considered indicative of severe exposure.



Urinary mercury (Hg) is the most reliable way to assess exposure to inorganic Hg, but the correlation between the levels of excretion in the urine and clinical symptoms is poor.



Urinary excretion of less than 4 mcg/g creatinine is not associated with any significant lead exposure.


Urinary excretion above 4 mcg/g creatinine is usually associated with pallor, anemia, and other evidence of lead toxicity.

Day(s) and Time(s) Performed

Monday through Saturday; 7 p.m.

Analytic Time

1 day

Specimen Retention Time

14 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

See Individual Test IDs

CPT Code Information






LOINC Code Information

Test ID Test Order Name Order LOINC Value
HMCRU Heavy Metal/Creat Ratio, w/Reflex,U In Process


Result ID Test Result Name Result LOINC Value
48544 Cadmium/Creatinine Ratio, U 13471-8
48546 Mercury/Creatinine Ratio, U 13465-0
48548 Lead/Creatinine Ratio, U 13466-8
CDCR Creatinine Conc 2161-8
48541 Arsenic/Creatinine Ratio, U 13463-5
48542 Arsenic Concentration w/Reflex 5586-3