Detecting lead toxicity due to occupational exposure
| Test Id | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| PBB | Lead, B | Yes, (order PBDV) | Yes |
| PPFE | Protoporphyrins, Fractionation, WB | Yes | Yes |
| DEMO5 | Patient Demographics | No | Yes |
PBB: Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
PPFE: High-Performance Liquid Chromatography (HPLC) with Fluorescence Detection
Exposure
Lead (Pb)
Pb (Lead)
Whole blood
This test is only for assessment of occupational exposure to lead. The preferred test for lead toxicity in children is blood lead. For more information see:
-PBDV / Lead, Venous, with Demographics, Blood
-PBDC / Lead, Capillary, with Demographics, Blood
The preferred screening test for suspicion of a hepatic porphyria is urine porphyrins. For more information see PQNRU / Porphyrins, Quantitative, Random, Urine.
Include a list of medications the patient is currently taking.
| Question ID | Description | Answers |
|---|---|---|
| VECP | Venous/Capillary | |
| PTADD | Patient Street Address | |
| PTCIT | Patient City | |
| PTSTA | Patient State | |
| PTZIP | Patient Zip Code | |
| PTCNT | Patient County | |
| PTPHO | Patient Home Phone | |
| PTRAC | Patient Race | |
| PTETH | Patient Ethnicity | |
| PTOCC | Patient Occupation | |
| PTEMP | Patient Employer | |
| GDFN | Guardian First Name | |
| GDLN | Guardian Last Name | |
| MDORD | Health Care Provider Name | |
| MDADD | Health Care Provider Street Address | |
| MDCIT | Health Care Provider City | |
| MDSTA | Health Care Provider State | |
| MDZIP | Health Care Provider Zip Code | |
| MDPHO | Health Care Provider Phone | |
| LABPH | Submitting Laboratory Phone |
Both EDTA whole blood and heparin whole blood specimens are required.
Patient Preparation:
1. High concentrations of gadolinium and iodine are known to interfere with most inductively couple 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.
2. Patient should abstain from alcohol for 24 hours prior to specimen collection.
Specimen Type: Whole blood
Supplies:
-Metal Free B-D Tube (EDTA), 6 mL (T183)
-Metal Free (Lead only) EDTA Tube, 3 mL (T615)
-Microtainer (EDTA) Tube, 0.5 mL (T174)
Container/Tube:
Preferred: Royal blue-top BD Vacutainer Plus with EDTA blood collection tube (BD catalog no. 368381)
Acceptable: Tan-top (lead only) BD Vacutainer Plus with EDTA blood collection tube, BD Microtainer with EDTA, or royal blue-top Monoject trace element blood collection tube
Specimen Volume: 2 mL
Collection Instructions:
1. See Metal Analysis Specimen Collection and Transport for complete instructions.
2. Send whole blood specimen in original tube. Do not aliquot.
3. Refrigerate specimen as soon as possible.
Specimen Type: Whole blood
Container/Tube:
Preferred: Green top (sodium heparin)
Acceptable: Dark blue top (metal free heparin), green top (lithium heparin), or lavender top (EDTA)
Specimen Volume: 4 mL
Collection Instructions: Refrigerate specimen as soon as possible after collection.
See Specimen Required
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Clotted blood | Reject |
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole blood | Refrigerated | 7 days |
Detecting lead toxicity due to occupational exposure
Lead is a heavy metal commonly found in man's environment that can be an acute and chronic toxin.
Lead was banned from household paints in 1978 but is still found in paint produced for nondomestic use and in artistic pigments. Ceramic products available from noncommercial suppliers (such as local artists) often contain significant amounts of lead that can be leached from the ceramic by weak acids, such as vinegar and fruit juices. Lead is found in dirt from areas adjacent to homes painted with lead-based paints and highways where lead accumulates from use of leaded gasoline. Use of leaded gasoline has diminished significantly since the introduction of nonleaded gasolines that have been required in personal automobiles since 1972. Lead is found in soil near abandoned industrial sites where lead may have been used. Water transported through lead or lead-soldered pipe will contain some lead with higher concentrations found in water that is weakly acidic. Some foods/beverages (eg, moonshine distilled in lead pipes) and some traditional home medicines contain lead.
Lead expresses its toxicity by several mechanisms. It avidly inhibits aminolevulinic acid dehydratase and ferrochelatase, 2 of the enzymes that catalyze synthesis of heme; the end result is decreased hemoglobin synthesis resulting in anemia and increased levels of erythrocyte zinc protoporphyrin.
Lead is also an electrophile that avidly forms covalent bonds with the sulfhydryl group of cysteine in proteins. Thus, proteins in all tissues exposed to lead will have lead bound to them. The most common sites affected are epithelial cells of the gastrointestinal tract and epithelial cells of the proximal tubule of the kidney.
The typical diet in the United States contributes 1 to 3 mcg of lead per day, of which 1% to 10% is absorbed; children may absorb as much as 50% of the dietary intake, and the fraction of lead absorbed is enhanced by nutritional deficiency. The majority of the daily intake is excreted in the stool after direct passage through the gastrointestinal tract. While a significant fraction of the absorbed lead is rapidly incorporated into bone and erythrocytes, lead ultimately distributes among all tissues, with lipid-dense tissues such as the central nervous system being particularly sensitive to organic forms of lead. All absorbed lead is ultimately excreted in the bile or urine. Soft-tissue turnover of lead occurs within approximately 120 days.
Avoidance of exposure to lead is the treatment of choice. However, chelation therapy is available to treat severe disease. Oral dimercaprol may be used in the outpatient setting except in the most severe cases.
LEAD: <3.5 mcg/dL
The Occupational Safety and Health Administration (OSHA) recommended limit for blood lead level is 40 mcg/dL (OSHA 1978).
The biological exposure index (BEI) for Pb in blood of exposed workers is 20 mcg/dL (ACGIH 2018).
Critical Values:
Pediatrics (< or =15 years): > or =20.0 mcg/dL
Adults (> or =16 years): > or =70.0 mcg/dL
PROTOPORPHYRINS, FRACTIONATION
Free Protoporphyrin: <20 mcg/dL
Zinc-Complexed Protoporphyrin: <60 mcg/dL
The Centers for Disease Control and Prevention (CDC) has identified the blood lead test as the preferred test for detecting lead exposure. The most recent National Health and Nutrition Examination Survey (NHANES) data show that 97.5 percentile for blood lead levels in US adults 16 years and older is 3.46 mcg/dL. In concurrence with the reference value concept that there is no safe level of lead in blood, the Council of State and Territorial Epidemiologists Occupational Health Subcommittee approved lowering the blood lead threshold from 5 mcg/dL to 3.5 mcg/dL for adults. For children younger than 6 years, the current reference level at which the CDC recommends public health actions be initiated is 3.5 mcg/dL. Chelation therapy is indicated when whole blood lead concentration is above 25 mcg/dL in children or above 45 mcg/dL in adults.
Occupational Safety and Health Standards: Lead (1983). 29 CFR Part 1910.1025 App C Action required for workers with Elevated Lead Values OSHA, Occupational Exposure to Lead, 1978:
| Number of tests performed | Whole blood lead concentration | Action required |
| 1 | > or =40 mcg/dL | Notification of worker in writing; medical examination of worker and consultation. |
| 3 (average) | > or =50 mcg/dL | Removal of worker from job with potential lead exposure. |
| 1 | > or =60 mcg/dL | Removal of worker from job with potential lead exposure. |
| 2 | <40 mcg/dL | Reinstatement of worker in job with potential lead exposure is based upon symptoms and medical evaluation. |
OSHA requirements in effect since 1978 call for the measurement of whole blood lead and zinc protoporphyrin (CLSI document C42-A, November 1996) to evaluate the occupational exposure to lead.
Elevated zinc protoporphyrin levels in adults may indicate long-term (chronic) lead exposure or may be indicative of iron deficiency anemia or anemia of chronic disease.
For protoporphyrin testing, patients must abstain from alcohol for at least 24 hours prior to specimen collection. Alcohol suppresses enzyme activity potentially leading to false-positive results.
1. Centers for Disease Control and Prevention. National Report on Human Exposure to Environmental Chemicals. CDC; Updated September 2023. Accessed December 5, 2023. Available at www.cdc.gov/exposurereport
2. Occupational Safety and Health Administration. Medical surveillance guidelines. Occupational Health and Safety Standards Toxic and Hazardous Substances from 1910.1025 App C. OSHA; 2001. Accessed December 5, 2023. Available at https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1025AppC
3. de Burbure C, Buchet J-P, 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(4):584-590
4. Kosnett MJ, Wedeen RP, Rothenberg SJ, et al. Recommendations for medical management of adult lead exposure. Environ Health Perspect. 2007;115(3):463-471
5. Jusko T, Henderson C, Lanphear B, et al. Blood lead concentrations <10 mcg/dL and child intelligence at 6 years of age. Environ Health Perspect. 2008;116(2):243-248
Lead
The metal of interest is analyzed by inductively coupled plasma mass spectrometry.(Unpublished Mayo method)
Protoporphyrins, Fractionation
Extraction followed by fractionation by high-performance liquid chromatography. Zinc protoporphyrin and free protoporphyrin are separately quantitated.(Smith RM, Doran D, Mazur M, Bush B. High-performance liquid chromatographic determination of protoporphyrin and zinc protoporphyrin in blood. J Chromatogr.1980;181[3-4]:319-327; Gou EE, Balwani M, Bissell DM, et al. Pitfalls in erythrocyte protoporphyrin measurement for diagnosis and monitoring of protoporphyrias. Clin Chem. 2015;61[12]:1453-1456. doi:10.1373/clinchem.2015.245456)
Monday, Wednesday, Friday
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.
83655
82542
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| PBPFD | Lead Profile Occ Exposure, B | 29588-1 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| 8602 | Lead, B | 77307-7 |
| 2327 | Zinc-Complexed Protoporphyrin | 2895-1 |
| 2326 | Free Protoporphyrin | 94491-8 |
| 29511 | Interpretation | 59462-2 |
| VECP | Venous/Capillary | 31208-2 |
| PTADD | Patient Street Address | 56799-0 |
| PTCIT | Patient City | 68997-6 |
| PTSTA | Patient State | 46499-0 |
| PTZIP | Patient Zip Code | 45401-7 |
| PTCNT | Patient County | 87721-7 |
| PTPHO | Patient Home Phone | 42077-8 |
| PTRAC | Patient Race | 32624-9 |
| PTETH | Patient Ethnicity | 69490-1 |
| PTOCC | Patient Occupation | 11341-5 |
| PTEMP | Patient Employer | 80427-8 |
| GDFN | Guardian First Name | 79183-0 |
| GDLN | Guardian Last Name | 79184-8 |
| MDORD | Health Care Provider Name | 52526-1 |
| MDADD | Health Care Provider Street Address | 74221-3 |
| MDCIT | Health Care Provider City | 52531-1 |
| MDSTA | Health Care Provider State | 52532-9 |
| MDZIP | Health Care Provider Zip Code | 87720-9 |
| MDPHO | Health Care Provider Phone | 68340-9 |
| LABPH | Submitting Laboratory Phone | 65651-2 |