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HelpTest Code MISC2MAYOPBUCR Lead/Creatinine Ratio, Random, 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.
Secondary ID
608908Useful For
Detecting clinically significant lead exposure, a toxic heavy metal, using random urine specimens
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| PBCU | Lead/Creatinine Ratio, U | No | Yes |
| CRETR | Creatinine, Random, U | No | Yes |
Special Instructions
Method Name
PBCU: Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)
CRETR: Enzymatic Colorimetric Assay
Reporting Name
Lead/Creat Ratio, Random,USpecimen Type
UrineSpecimen 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.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.
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)
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)
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. 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 |
Day(s) Performed
Monday through Friday