TMPPM 2011 > Children's Services Handbook > Appendix C: Lead Screening > Measuring Blood Lead Levels

C.3 Measuring Blood Lead Levels

A blood lead test is the only definitive method to detect recent or ongoing exposure. BLLs are measured as micrograms of lead per deciliter (µg/dL) of whole blood. The Centers for Disease Control and Prevention (CDC) define a blood lead level of 10µg/dL as a level of concern. This is the measurement standard in Texas for an EBLL and requires follow-up. The blood lead "level of concern" should not be interpreted as a definitive toxicological threshold. Mounting evidence suggests adverse health effects in children with BLLs below 10µg/dL.

Blood lead tests, in order of occurrence:

•Screening test-A blood lead test that indicates whether a client may have an EBLL.

•Diagnostic test-A venous blood lead test that is performed within recommended guidelines to determine the status of a client who has previously had an EBLL on a screening test (See Pb:109 for recommended guidelines). Unless the diagnostic test is performed within four weeks of the screening date, it is not a diagnostic test but rather a new screening test.

•Follow-up test-A venous blood lead test to monitor the status of a client with a previously elevated diagnostic test for lead.

Note: A follow-up test is not related to the THSteps follow-up visit. A visit to monitor a child with EBLL would be submitted as an acute care evaluation and management (E/M) visit.

Providers are responsible for conducting a diagnostic test when a screening test finds a lead level of 10µg/dL or greater. Blood for a screening test may be drawn from a venous or capillary site. A venous blood draw is strongly recommended and preferred. To order free venous sample supplies from the DSHS Laboratory, call (toll free) 1-888-963-7111, Ext. 7661.

Note: The capillary lead screen analysis is subject to a false positive result from skin lead contamination during collection. A soap and water wash of the patient's hands or feet and the collector's hands (or the wearing of gloves) must be performed to minimize the chance of contamination. Alcohol cleansing alone is not sufficient.

If the screening test is 10µg/dL or above, recalling a client for a diagnostic sample may be billed as a THSteps follow-up visit. If the screening test was rejected due to clotting, insufficient quantities, or perceived contamination, the provider must repeat the sample as a diagnostic test. Again, the provider may bill the visit and analysis as an E/M visit. Providers can submit the specimen to the DSHS Clinical Chemistry Laboratory using the appropriate Department of State Health Services (DSHS) Laboratory Specimen Submission form (the same way as for all other THSteps laboratory blood specimens). If the initial blood lead test is collected as part of a THSteps medical checkup, it must be submitted to the DSHS Laboratory; diagnostic and follow-up tests for the same client may be sent to a private laboratory.

Refer to: Subsection C.5, "Form Pb-109: Reference for Follow-up Blood Lead Testing and Medical Case Management" in this appendix for interpretation of laboratory test results and guidelines for follow-up for clients with elevated blood lead levels.

Subsection 5.3.2.7.6, "Required Laboratory Tests Related to Medical Checkups" in this handbook.

Subsection 5.3.1.8, "Newborn Examination" in this handbook.

Providers can find more information about the medical and environmental management of lead-poisoned children on the DSHS Texas Childhood Lead Poisoning Prevention Program (TX CLPPP) website at www.dshs.state.tx.us/lead or by calling 1-800-588-1248.