Test ID: LEADO
Lead Profile Occupational Exposure, Blood
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Detecting lead toxicity and monitoring treatment
Profile Information A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| XLEAD | Lead, B | Yes, (order LEADB) | Yes |
| ZPPB | Zinc Protoporphyrin, B | Yes, (order NEZPP) | Yes |
| DEMO | Patient Demographics | No | Yes |
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
XLEAD/300104: Atomic Absorption
ZPPB/300110: Hematofluorometry
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Pb (Lead)
Exposure
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube:
Preferred: Royal blue-top Monoject trace element blood collection tube product #8881-307022 (Supply T183), containing EDTA as an anticoagulant
Acceptable: Tan top (lead only) Becton-Dickinson tube (Supply T615) or a Becton-Dickinson MICROTAINER (Supply T174)
Specimen Volume: 2 mL
Collection Instructions: See Metals Analysis-Collection and Transport in Special Instructions for complete instructions.
Additional Information: Patient's date of birth is required.
Forms: Lead/Heavy Metals Reporting Form (Supply T491) in Special Instructions.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | See individual unit codes |
| Lipemia | See individual unit codes |
| Icterus | See individual unit codes |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Whole blood | Refrigerated | 14 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Lead is a heavy metal commonly found in the man's environment that can be an acute and chronic toxin.
Lead is present in paints manufactured before 1970. It was banned from household paints in 1972 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 unleaded gasoline, which has 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 (eg, moonshine distilled in lead pipes) and some traditional home medicines contain lead.
Exposure to lead from any of these sources either by ingestion, inhalation, or dermal contact can cause significant toxicity.
Lead expresses its toxicity by several mechanisms. It avidly inhibits aminolevulinic acid dehydratase (ALA-D) and ferrochelatase, 2 of the enzymes that catalyze synthesis of heme. Inhibition of ALA-D and ferrochelatase causes accumulation of delta aminolevulinic acid in urine and protoporphyrin in erythrocytes, which are markers for significant lead exposure.
Lead also is an electrophile that avidly forms covalent bonds with the sulfhydryl group of cysteine in proteins. Thus, proteins in any tissues exposed to lead will have lead bound to them.
Keratin in hair contains a high fraction of cysteine relative to other amino acids. The cysteine residues are cross-linked through lead, thereby causing the tertiary structure of the protein to change; cells of the nervous system are particularly susceptible to this effect. Some lead-bound proteins change their tertiary configuration sufficiently that they become antigenic; renal tubular cells are particularly susceptible to this effect because they are exposed to relatively high lead concentrations during clearance.
A typical diet in the United States contributes approximately 300 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 lead absorbed 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. British anti-Lewisite (BAL) administered intravenously was the classical mode of chelation therapy. Oral dimercaprol has recently become available and is being used in the outpatient setting except in the most severe cases.
Measurement of urine excretion rates either before or after chelation therapy has been used as an indicator of lead exposure. However, blood lead analysis has the strongest correlation with toxicity.
Erythrocyte protoporphyrin (EP) is a biologic marker of lead toxicity and was previously used in conjunction with blood lead assays to screen for lead poisoning in children. However, because of poor sensitivity and specificity, EP is no longer recommended for lead screening in children. However, EP remains a useful tool for monitoring treatment of individuals with confirmed elevated lead levels.
Lead screening in children and protocols for assessment for treatment have been detailed by the Centers for Disease Control and Prevention (CDC).
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
LEAD
0-6 years: 0-4 mcg/dL
>or =7 years: 0-9 mcg/dL
Critical values
Pediatrics (< or =15 years): > or =20 mcg/dL
Adults (> or =16 years): > or =70 mcg/dL
ZINC PROTOPORPHYRIN
<100 mcg/dL
Interpretation Provides information to assist in interpretation of the test results
The Centers for Disease Control and Prevention (CDC) has identified the blood lead test as the preferred test for detecting lead exposure in children. Chronic whole blood lead levels <10 mcg/dL is often seen in children. For pediatric patients, there may be an association with blood lead values of 5 mcg/dL to 9 mcg/dL and adverse health effects. Follow up testing in 3 to 6 months may be warranted. Chelation therapy is indicated when whole blood lead concentration is >45 mcg/dL.
The Occupational Safety and Health Administration (OSHA) has published the following standards for employees working in industry:
-Employees with whole blood lead >60 mcg/dL must be removed from workplace exposure.
-Employees with whole blood lead >50 mcg/dL averaged over 3 blood samplings must be removed from workplace exposure.
-An employee may not return to work in a lead exposure environment until whole blood lead is <40 mcg/dL.
An elevated erythrocyte protoporphyrin (EP) indicates impairment of the heme biosynthetic pathway. Elevated EP levels in adults may indicate long-term lead exposure. Expected EP levels seen in heavy metal toxicity are in the range of >100 mcg/dL.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
No significant cautionary statements
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Occupational Safety and Health Administration: OSHA Lead Standard - Requirements from the General Industry Standards Lead (1910, 1025), from 29 CFR 1910, 1025, A.M. Best Safety and Security - 2000. Retrieved March 2000. Available from URL: ambest.com/safety/osha/chap10g.html
2. Centers for Disease Control and Prevention. Screening Young Children for Lead Poisoning. Guidance for State and Local Public Health officials. Atlanta, GA: US Dept of Health and Human Services. Public Health Service: November 1997 Available from URL: cdc.gov/nceh/lead/guide/guide97.htm
3. Belinger D, Leviton A, Waternaux C, et al: Longitudinal analyses of prenatal and postnatal lead exposure and early cognitive development. N Engl J Med 1987 Apr 23;316(17):1037-1043
4. Needleman HL, Schell A, Bellinger D, et al: The long-term effects of exposure to low doses of lead in childhood. An 11-year follow-up report. N Engl J Med 1990 Jan 11;322(2):83-88
5. Nixon DE, Moyer TP, Windebank AJ, et al: Lack of correlation of low levels of whole blood and serum lead in humans: an experimental evaluation in animals. In Trace Substances in Environmental Health XIX. Proceedings of the University of Missouri's 19th Annual Conference on Trace Substances in Environmental Health, Columbia, MO, 1985, pp 248-256
Method Description Describes how the test is performed and provides a method-specific reference
Zinc protoporphyrin is measured on the Helena ProtoFluor-Z hematofluorometer using a multi-channel front surface photofluorometer. When the sample is exposed to 415 nm light, zinc protoporphyrin (ZPP) is excited and emits light at 595 nm. A second lens/filter system collects, filters, and focuses the 595 nm light onto a photomultiplier tube (PMT). The PMT produces a current level in response to the light reaching it, which is proportional to the ZPP/heme ratio. During the 5 second reading, over 1,000 light-level readings are taken and averaged by the microcomputer and a value is displayed in mcmol ZPP/mol heme. The instrument can also convert this result to mcg ZPP/dL whole blood by changing the instrument mode. (Operator’s Manual: Helena ProtoFluor-Z 7/2006)
Lead in blood is determined by graphite furnace atomic absorption spectrometry. Samples are prediluted with a matrix modifier solution. The sample is then deposited in a depression on a carbon rod in an unclosed chamber. The furnace is electrically heated to a temperature sufficient to vaporize the lead in the sample. Light emitted from a hollow cathode lamp at 283.3 nm is absorbed by the vaporized atoms in the ground state. The concentration of lead in a sample is determined by comparing its measured emission signal with those obtained from a blank and calibration standards. Quantitative measurement is based on Beer's Law. (Parsons PJ, Slavin W: A rapid Zeeman graphite furnace atomic absorption spectrometric method for determination of lead in blood, Spectorchimica Acta 1993;48B[6/7]:925-939)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
83655-Lead
84202-Protoporphyrin, RBC; Quantitative
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 300110 | Zinc Protoporphyrin, B | 33007-6 |
| STADD | Street Address | In Process |
| PB_LB | Lead, B | 5671-3 |
| CITY | City | N/A |
| STATE | State | N/A |
| ZIP | Zip | 45401-7 |
| CNTY | County | N/A |
| GRDFN | Guardian first name | N/A |
| GRDLN | Guardian last name | N/A |
| HOMPH | Home Phone | 42077-8 |
| VENCP | Venous/Capillary | 31208-2 |
| DRACE | Race | 32624-9 |
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