Which specimen type is most appropriate for detecting lead exposure via standard toxicology testing?

Which specimen type is most appropriate for detecting lead exposure via standard toxicology testing?

• A. Serum
• B. Plasma
• C. Whole blood
• D. CSF

Answer: (C)

Lead exposure is best assessed using whole blood because most of the circulating lead is bound to red blood cells. This makes the whole-blood lead level a direct reflection of recent exposure, typically over the past several weeks, which is what standard toxicology testing aims to gauge. Serum or plasma lead levels are not reliable for this purpose because lead partitions heavily into cells, so their concentrations are lower and don’t correlate well with total body burden or recent exposure. CSF isn’t used for routine lead screening. In practice, a venous whole-blood sample collected in a contamination-free tube is analyzed by methods such as atomic absorption spectrometry or ICP-MS to determine the lead level.

Lead exposure is best assessed using whole blood because most of the circulating lead is bound to red blood cells. This makes the whole-blood lead level a direct reflection of recent exposure, typically over the past several weeks, which is what standard toxicology testing aims to gauge. Serum or plasma lead levels are not reliable for this purpose because lead partitions heavily into cells, so their concentrations are lower and don’t correlate well with total body burden or recent exposure. CSF isn’t used for routine lead screening. In practice, a venous whole-blood sample collected in a contamination-free tube is analyzed by methods such as atomic absorption spectrometry or ICP-MS to determine the lead level.