Investigations

1st investigations to order

whole-blood lead level

Test
Result
Test

Venous whole blood is drawn and submitted using lead-free materials. Samples must be anticoagulated as requested by the laboratory, usually in heparin.

There is no 'normal' level, and interventions should begin at the first sign of increased exposure.

A rise in whole-blood lead from 0.1 micromoles/L (2-3 micrograms/dL) to 0.5 micromoles/L (10 micrograms/dL) results in a significant loss of IQ in children; the loss is more pronounced at these concentrations than at levels above 0.5 micromoles/L (10 micrograms/dL).[27][28][30][54] However, most environmental interventions at these lower levels have not been demonstrated to decrease blood lead, so prevention is key to preventing this IQ loss.

Result

≥0.17 micromoles/L (3.5 micrograms/dL) in children; case definition ≥0.24 micromoles/L (5 micrograms/dL) in an adult (person ≥16 years of age); US Occupational Safety and Health Administration considers an adult blood lead level of ≥1.2 micromoles/L (25 micrograms/dL) to be serious

full blood count

Test
Result
Test

Iron deficiency anaemia may co-exist with lead exposure.

Result

variable; may show microcytic hypochromic anaemia

serum ferritin

Test
Result
Test

Iron deficiency anaemia may co-exist with lead exposure.

Result

variable; may be reduced

Investigations to consider

24-hour urine lead with chelation

Test
Result
Test

Not a primary diagnostic tool but is used to determine efficacy of chelation therapy and the need for further chelation.

24-hour urine is collected in a lead-free container for submission to the laboratory.

Result

adequate chelation is defined as lead-to-chelant ratio >1 microgram lead/milligram chelant

abdominal radiographs

Test
Result
Test

Indicated for children or adults suspected of ingesting lead materials.

Result

variable; radio-opaque material may be detected in abdomen

nerve conduction studies

Test
Result
Test

Considered in patients with peripheral neuropathy.

Useful for monitoring disease progression.

Result

variable; may show slowing of nerve conduction velocities

Emerging tests

x-ray fluorescence of long bones

Test
Result
Test

To document extent of long-term lead exposure; used to measure lead in long bones, usually the tibia.

High cost and lack of interlaboratory standardisation of methods and results have limited its clinical application.[56][57]

Result

standards are laboratory-specific

MRI brain

Test
Result
Test

Lead exposure, including during childhood, has been associated with altered brain structure and function.[58][59][60] MRI scanning can be considered; it may show decreased brain volume and alterations in myelination and axonal integrity.[61]

Result

decreased brain volume; altered myelination and axonal integrity

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