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Epic Code LAB1230734 Lead/Creatinine Ratio, Random, Urine

Reporting Name

Lead/Creat Ratio, Random,U

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Clinical Information

Increased urine lead concentration per gram of creatinine indicates significant lead exposure. Measurement of urine lead concentration per gram of creatinine before and after chelation therapy have been used as an indicator of significant lead exposure. However, the American College of Medical Toxicology (ACMT 2010) position statement on post-chelator challenge urinary metal testing states that "post-challenge urinary metal testing has not been scientifically validated, has no demonstrated benefit, and may be harmful when applied in the assessment and treatment of patients in whom there is concern for metal poisoning."

 

Blood lead is the best clinical correlation of toxicity.

 

For additional information, see PBDV / Lead, Venous, with Demographics, Blood.

Useful For

Detecting clinically significant lead exposure, a toxic heavy metal, using random urine specimens

Specimen Type

Urine


Ordering Guidance


The CDC recommends venous blood collection for lead testing; see PBDV / Lead, Venous, with Demographics, Blood.



Specimen Required


Patient Preparation: 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 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 Trace Metals Analysis Specimen Collection and Transport in Special Instructions for complete instructions.


Specimen Minimum Volume

1.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  14 days

Reject Due To

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

Day(s) Performed

Monday through Friday

Reference Values

0-17 years: not established

≥18 years: <2 mcg/g creatinine

Interpretation

Measurements of urinary lead (Pb) levels have been used to assess lead exposure. However, like lead blood, urinary lead excretion mainly reflects recent exposure and thus shares many of the same limitations for assessing Pb body burden or long-term exposure.(1,2)

 

Urinary lead concentration increases exponentially with blood lead and can exhibit relatively high intra-individual variability, even at similar blood lead concentrations.(3,4)

Cautions

No significant cautionary statements.

Clinical Reference

1. Sakai T: Biomarkers of lead exposure. Ind Health. 2000;38(2):127-142

2. Skerfving S: Biological monitoring of exposure to inorganic lead. In: Clarkson TW, Friberg L, Nordberg GF, Sager PR, eds. Biological Monitoring of Toxic Metals. Rochester Series on Environmental Toxicity. Springer; 1988:169-197

3. Gulson BL, Jameson CW, Mahaffey KR, et al: Relationships of lead in breast milk to lead in blood, urine, and diet of the infant and mother. Environ Health Perspect. 1998;106(10):667-674

4. Skerfving S, Ahlgren L, Christoffersson JO: Metabolism of inorganic lead in man. Nutr Res 1985;Suppl 1:601-607

5. Kosnett MJ, Wedeen RP, Rotherberg SJ, et al: Recommendations for medical management of adult lead exposure. Environ Health Perspect. 2007;115:463-471

6. de Burbane C, Buchet JP, Leroyer A, et al: Renal and neurologic effects of cadmium, lead, mercury, and arsenic in children: evidence of early effects and multiple interactions at environmental exposure levels. Environ Health Perspect. 2006;114:584-590

7. Strathmann FG, Blum LM: Toxic elements. In: Rifai N, Horwath AR., Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:chap 42

Method Name

PBCU: Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)

CRETR: Enzymatic Colorimetric Assay

Method Description

Lead (Pb) in urine is analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) in kinetic energy discrimination (KED) mode using gallium (Ga), rhodium (Rh), and iridium (Ir) as internal standards and a 5% nitric acid salt matrix calibration.(Unpublished Mayo method)

Report Available

1 to 3 days

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

83655

82570

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PBUCR Lead/Creat Ratio, Random,U 13466-8

 

Result ID Test Result Name Result LOINC Value
608904 Lead/Creatinine Ratio, U 13466-8
CRETR Creatinine, Random, U 2161-8

Profile Information

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